Search

Silicon ring resonators on SOI substrates are well known and widely studied devices for silicon photonics-based systems. They are commonly used in datacom and highperformance computing for wavelength multiplexing, modulation and spectral filters. They can be tuned to the desired frequency with resistive heaters, which is the primary power budget of the device. In this work, backside cavities have been successfully etched in the bulk of the SOI substrate below ring resonators to improve heat trapping within the silicon rings. Simulations show that those backside cavities improve significantly heat confinement and minimizes locally heat losses due to conduction in the Si substrate. All the processes used in this study are compatible with the standard silicon photonics interposer process flow. A 72% power consumption reduction for a $10\ \mu\mathrm{m}$ diameter ring resonator on SOI has been achieved with a backside opening of $100\ \mu\mathrm{m}$ deep and $40\ \mu\mathrm{m}$ diameter, in good agreement with simulation results. Most importantly, the cavities opening did not impact the optical performances of the ring. Dynamic behavior of the rings was also studied, and show that the presence of cavities increases the thermal switching time of the rings.

Ion-exchange on glass is one of the major technological platforms that are available to manufacture low-cost, high performance Planar Lightwave Circuits (PLC). In this paper, the principle of ion-exchanged waveguide realization is presented. Then a review of the main achievements observed over the last 30 years will be given. The focus is first made on devices for telecommunications (passive and active ones) before the application of ion-exchanged waveguides to sensors is addressed.

International audience; Optical waveguides, where propagating modes inter- act with a magnetized magneto-optical layer, show non-reciprocal properties such as mode conversion, phase shift and absorption. These properties are essential in order to make an efficient integrated isolator. In this paper, we explain how a well-calibrated polarimetric setup can be used to measure all the magneto-optical characteristics of a waveguide, in order to advance towards well- controlled integrated optical isolators.

Understanding the origin and protocols to induce performance degradations of silicon photonics high speed photodetector represent a major issue for the qualification of the reliability of these devices. Using advanced characterization technics, it is shown that the dark current, the photonic current and the cut-off frequency of the photodiode can be degraded during voltage stress of 106 s, which could ultimately induce some significant device performance drift and failure. An explanation of these degradations is presented based on both electrical characterization and device modelling. The observed degradations of both dark current and responsivity can indeed be modeled by a single carrier lifetime degradation, attributed to an increase of the surface recombination rate, impacting an unexpected large contribution of carrier diffusion in the photocurrent. The results obtained with this model are experimentally confirmed by extracting the activation energy of the dark current, before and after stress. The improved physical understanding of the degradation is expected to lead to shorter test protocols for silicon photonics devices.

International audience; In this paper, we study the capacity of glass integrated optics DFB lasers to generate millimeter wave and terahertz frequencies. We present the different technological parameters that can be adjusted to generate frequencies up to 8.8THz by photomixing two free running DFB lasers on glass. The impact of each parameter is explicitly demonstrated using simulations and experimental measurements.

In this paper, the reliability of germanium photodiodes of the PIC25G technology for silicon photonic applications is experimentally studied. Using advanced characterization technics, it is shown that the dark current, the photonic current and the cut-off frequency of the photodiode can be degraded during voltage stress of 106 s, which could ultimately induce some device performance drift. The causes of these degradations are presently attributed to interface defects between germanium and SiO 2 , until more detailed investigation are pursued.

In this paper, we report the generation of millimeter-wave carriers using two free-running DFB lasers on Erbium doped glass emitting at 1.5μm. Carriers with ultra-narrow linewidth are generated. For the generated signals, the thermal tunability is studied and the optical and electrical powers variations of the signals are measured to be ±0.3dB and ±5dB for lasers temperatures between 10°C and 70°C.

In this Letter, the impact of thermal coupling between two glass laser cavities on a heterodyned signal for millimeter-wave frequency generation is presented. In addition to a narrow heterodyne linewidth estimated to be lower than 1 kHz, the frequency drift is reduced to ±16.5 ppm/7 s. The signal quality is also evaluated by performing data transmission, respecting communication standards at 60 GHz using complex modulation formats.

In this paper, an integrated passively Q-switched DBR laser made in glass integrated optics technology is designed, fabricated and investigated. The laser, operating at 1030 nm wavelength, is formed by an ion-exchanged single mode waveguide realized in an Ytterbium doped phosphate glass. The feedback is provided by a DBR structure made of a Fiber Bragg Grating and a dielectric mirror. The Q-switched behavior is obtained by hybridizing the saturable absorber on the waveguides, so that it interacts with the evanescent part of the guided field. The saturable absorber we use is a bis(4-dimethylaminodithiobenzil)nickel (BDN) dye incorporated in a polymeric film. Using this structure, we were able to demonstrate a Q-switched operation for several BDN concentrations, allowing to vary the pulse duration and the repetition rate of the device. Moreover, we report a very narrow 372 MHz wide emission spectrum while in Q-switched regime.

International audience; In order to enhance electro-optical system-in-package capabilities for silicon photonics, a cost effective fabrication process for optical waveguides integration on thin glass substrate interposer is demonstrated. Firstly, a femtosecond laser ablation coupled with a hydrofluoric acid etching is developed to create micro grooves at the glass surface. Secondly, a dry film lamination followed by chemical mechanical planarization is achieved to define surface optical waveguides by filling the micro channels. Physical characterizations of the fabricated waveguides are performed using optical and scanning electron microscopy. Finally, optical mode profile and loss characterizations confirm the optical functionality of waveguides which prove to be multimodal at 1550 nm.

International audience; In this paper we demonstrate the monolithic integration of a fully CMOS compatible hybrid DBR laser on the backside of a SOI wafer. This innovative approach allowed implementing CMOS compatible electric interconnects and optical sources on a same chip. The optical characterizations confirm the single wavelength behavior of the realized devices which present a SMSR higher than 35 dB and can be tuned over 4 nm, opening the route to a fully integrated optical transceiver on a Si platform.

International audience; Research in nuclear safety and fuel reprocessing has led to a surging need for novel chemical analysis tools with reduced analyte and effluent volumes. Recent technological advances for the elaboration and packaging of glass optofluidic co - integrated sensors have opened up the way for said analysis in harsh environments. We discuss a sensor engineering approach for the construction of an integrated absorption spectrometer with an ion-exchange core. Pu(VI) oxidation state exhibits a major absorption peak at a wavelength of 831 nm with a molar absorption coefficient of 545 L.mol-1.cm-1. An evanescent waveguiding sensing structure that allows guided fluid/light interaction is investigated in order to provide absorption spectroscopy measurements. The work presented consists of optical simulations as well as experimental measurements. Waveguide engineering with respects to modal transmission, field/fluid interaction coefficient Γ and device losses is presented. The simulations are carried out by computing ion-exchanged waveguide refractive index distribution and using it in mode solver software. Device optical characterization and bench tests are carried out to verify approach viability. First device measurements of a neodymium absorption peak in nuclear manipulation conditions are displayed.

In this paper, the simulation, design and fabrication of a back-side coupling (BSC) concept for silicon photonics, which targets heterogeneous hybrid III-V/Si laser integration is presented. Though various demonstrations of a complete SOI integration of passive and active photonic devices have been made, they all feature multi-level planar metal interconnects, and a lack of integrated light sources. This is mainly due to the conflict between the need of planar surfaces for III-V/Si bonding and multiple levels of metallization. The proposed BSC solution to this topographical problem consists in fabricating lasers on the back-side of the Si waveguides using a new process sequence. The devices are based on a hybrid structure composed of an InGaAsP MQW active area and a Si-based DBR cavity. The emitted light wavelength is accordable within a range of 20 nm around 1.31μm thanks to thermal heaters and the laser output is fiber coupled through a Grating Coupler (GC). From a manufacturing point of view, the BSC approach provides not only the advantages of allowing the use of a thin-BOX SOI instead of a thick one; but it also shifts the laser processing steps and their materials unfriendly to CMOS process to the far back-end areas of fabrication lines. Moreover, aside from solving technological integration issues, the BSC concept offers several new design opportunities for active and passive devices (heat sink, Bragg gratings, grating couplers enhanced with integrated metallic mirrors, tapers…). These building boxes are explored here theoretically and experimentally.

The fabrication of on-chip optical isolators to protect integrated optical sources is one of the major challenges of research in integrated optics. Their operation principle is based on the control of the guided-wave polarization and the most common structures are composed of a polarization splitter, a non-reciprocal rotator based on the Faraday effect, and a reciprocal rotator. The reciprocal rotator is a device that rotates the wave polarization by 45°. This can be achieved by creating a relative phase shift between the waveguide’s two polarization eigen states or by twisting its optics axis thanks to an appropriate shaping of its core. In this work, we propose the design and simulation of a waveguide with optics axes tilted by 45° fabricated by two cascaded field-assisted ion exchanges on a glass substrate and an encapsulation. The dependences of the proposed design on process time, temperature, applied voltage and photolithography over-etching are investigated. The final device exhibits a 45.1° rotation of its optical axes and less than 5% variation on the C+L telecommunication band.

International audience; Advances in nuclear fuel reprocessing have led to a surging need for novel chemical analysis tools. In this paper, we present a packaged lab-on-chip approach with co-integration of optical and micro-fluidic functions on a glass substrate as a solution. A chip was built and packaged to obtain light/fluid interaction in order for the entire device to make spectral measurements using the photo spectroscopy absorption principle. The interaction between the analyte solution and light takes place at the boundary between a waveguide and a fluid micro-channel thanks to the evanescent part of the waveguide’s guided mode that propagates into the fluid. The waveguide was obtained via ion exchange on a glass wafer. The input and the output of the waveguides were pigtailed with standard single mode optical fibers. The micro-scale fluid channel was elaborated with a lithography procedure and hydrofluoric acid wet etching resulting in a 150±8 μm deep channel. The channel was designed with fluidic accesses, in order for the chip to be compatible with commercial fluidic interfaces/chip mounts. This allows for analyte fluid in external capillaries to be pumped into the device through micro-pipes, hence resulting in a fully packaged chip. In order to produce this co-integrated structure, two substrates were bonded. A study of direct glass wafer-to-wafer molecular bonding was carried-out to improve detector sturdiness and durability and put forward a bonding protocol with a bonding surface energy of γ>2.0 J.m-2. Detector viability was shown by obtaining optical mode measurements and detecting traces of 1.2 M neodymium (Nd) solute in 12±1 μL of 0.01 M and pH 2 nitric acid (HNO3) solvent by obtaining an absorption peak specific to neodymium at 795 nm.

We study the miniaturization of Thermal Lens Spectrometry (TLS) towards Lab-on-chip integration in order to reduce the volume of fluid assays in nuclear process control. TLS is of great interest in this context since it combines the advantages of optical detection methods with an inherent suitability for small-scale samples. After validating the experimental principle in a classical thermal lens crossed-beam setup, we show the integration of a Young-interferometer with a microcapillary on a glass substrate, reducing the necessary sample size to 400 nl. The interferometer translates the photothermally induced refractive index change in the fluid to a phase shift of the fringe pattern, which can then be detected by a camera. Measurements of Co(II) in ethanol yield a detection limit of $c = 5 \times 10^{-4}$ M for the crossed-beam setup and $c = 6 \times 10^{-3}$ M for the integrated sensor. At an interaction length of 10 $\mu$ m, it detects a minimum absorbance of $K = 1.2 \times 10^{-4}$ in a probed volume of 14 pl.

In order to realize an integrated optical isolator, a new hybrid optical structure has been proposed. This structure is composed of an active magneto-optic garnet layer with a strong refractive index, transferred on a passive ion-exchanged glass waveguide. Given the thermal restraints relating to the stability of the glass waveguides, the process used to achieve this hybrid structure is composed of two main steps: firstly, good quality garnet films were grown by liquid phase epitaxy, then these active films were bonded successfully on glass wafer. According to modelling, the thickness of the garnet layer does not exceed 300 nm for maintaining a good confinement. Good wafer bondings on ion-exchanged glass waveguides are obtained.

One of the technological challenges of direct observation of extra-solar planets by nulling interferometry is the development of a modal filter operating from 6 to 20 μm. In the present paper a candidate technology for the fabrication of such modal filters is presented: Integrated Optics. A solution based on all-telluride buried channel waveguides is considered. In the proposed waveguides, vertical guiding of light is achieved by a 15 μm-thick Te 83 Ge 17 core film deposited onto a lower-index Te 75 Ge 15 Ga 10 substrate, and covered by a 15 μm-thick Te 76 Ge 24 superstrate. Horizontal guiding of light is obtained by modifying the geometry of the core layer by ion beam etching. As this stage, all-telluride buried channel waveguide prototypes demonstrate light guiding and transmission from 2 to 20 μm. The validity of the technology and the good quality of the fabrication process, in particular the input and output facets surface finish are thus confirmed. These results consolidate the potential of Te-based integrated optics components for nulling interferometry.

Er-doped and Er/Yb-codoped glasses have a key role in the production of lasers and amplifiers for optical communication systems and eye-safe sensors operating at wavelengths around 1550 nm. Ion-exchanged waveguides on Er/Yb-codoped phosphate glass allow implementing quite compact and efficient active devices. Unfortunately, these wafers are not compatible with the integration of passive functions since unpumped erbium ions absorb 1550 nm signal. Hence, an efficient monolithic co-integration of passive and active optical functions requires hybridizing doped and undoped glasses. In this paper, we present the realization of a fully encapsulated three-dimensional distributed feedback (DFB) hybrid laser obtained by the wafer bonding of two ion-exchanged substrates. On the first one, an undoped silicate glass, a selectively buried channel core waveguide is made by a Ag + /Na + exchange and a field-assisted burial. A Bragg grating is then etched on the wafer surface. On the second wafer, an Er/Yb-codoped phosphate glass, a slab core waveguide is obtained by a Ag + /Na + exchange. The two wafers are finally bonded together yielding to a DFB laser: the interaction between the guided light and the doped glass provides the amplification, while the Bragg grating supplies the feedback. With this fully encapsulated device, (420±15) µW laser emission has been observed at 1534 nm for (390±20) mW injected pump power, while its input and output are totally insulated from the doped wafer.

Ion-exchange can be used to locally increase the refractive index of a glass, thus allowing the fabrication of optical waveguides. This technology has been used for decades to obtain passive and active devices. In particular, integrated Q-switched lasers have been recently achieved. The high optical power from pulsed lasers in combination with the light confinement of waveguides allows designing devices for nonlinear applications. For example, nonlinear phenomena is recognized as an essential mechanism of spectral broadening needed for the realization of supercontinuum laser sources. In this paper we investigate the power handling capabilities of waveguides made by ion-exchange. First, the fabrication technology based on the Ag + /Na + exchange will be briefly presented for surface and buried waveguides. Both types of waveguides are then designed in order to minimize their effective area. These waveguides are fabricated, their damage threshold and effective area are characterized, 4.8±0.5 μm 2 and 14.2±1.4 μm 2 effective area are reached for surface and buried waveguides respectively. Their ability to handle high optical power density, 25±13 GW/cm 2 and 65±39 GW/cm 2 respectively is assessed and the main cause for optical damage in silver ion-exchanged waveguides is investigated.

Summary We report the characterization of an integrated Ag+/Na+ ion exchange waveguide realized in a silicate glass substrate using apertureless scanning near-field optical microscopy. Our experimental set-up is based on the combination of a commercial atomic force microscope with an optical confocal detection system. Thanks to this system, the topography and evanescent optical field at the waveguide top surface are mapped simultaneously. Also, the process of apertureless scanning near-field optical microscopy image formation is analysed. In particular, fringe patterns appearing in the image reveal the intrinsic interferometric nature of the collected signal, due to interference between the field scattered by the tip end and background fields related to guide losses. We give a quantitative interpretation of these fringes. Evanescent intensity mapping on the sample surface allowed us to extract physical waveguide parameters. In particular, it shows an unambiguous multimode beat along the waveguide propagation axis. Furthermore, we show that analysis of this intensity profile reveals back-reflection effects from the waveguide exit facet. The resulting standing waves pattern allows us to evaluate the eigenmode propagation constants.

One of the technological challenges of direct observation of extra-solar planets remains to develop a modal filter operating from 6 to 20 μm. In the present paper we present one of the two candidate technologies for the fabrication of such modal filters, together with Fiber Optics: Integrated Optics. The solution based on alltelluride buried channel waveguides was considered. In the so-called waveguides, the vertical confinement of the light is achieved in a higher-index core layer consisting in a 15 μm-thick Ge 17 Te 83 film which is deposited onto a lower-index Te 75 Ge 15 Ga 10 substrate, and further covered by a lower-index superstrate consisting in a 15 μm-thick Ge 24 Te 76 film. Concerning the horizontal confinement of the light, it is obtained by etching the core layer. As this stage, the all-telluride buried channel waveguides are proved to transmit light from 2 to 5 μm and to behave as channel waveguides with a satisfactory confinement of the light. It confirms the validity of the technology and the good quality of the input and output facets. Tests between 6 and 20 μm are being performed and will allow giving a confirmation of the potential of Te-based integrated optics components for nulling interferometry.

The development of pulsed lasers allows increasing the power density into integrated waveguides to a level compatible with the generation of nonlinear phenomena, opening the route to the realization of integrated supercontinuum sources. In this paper, we investigate the spectral broadening of a laser pulse through Raman scattering processes in normal dispersion regime with nanosecond pumping. The obtained experimental results are compared to an experimental model based on a single fiber with the same confinement and perspectives in terms of integrated broadband sources are presented.

A passively Q-switched distributed-Bragg-reflector laser made in glass integrated optics technology, and operating around 1030 nm, is designed, realized and investigated. The laser is formed by an ion-exchanged single mode waveguide realized in an Ytterbium doped phosphate glass. The Q-switching behavior is obtained by hybridizing a saturable absorber film on the waveguides. This allows the realization of a short and simple laser cavity having both pulsed and a narrow linewidth emission. Its experimental characterization leads to the observation of a stable repetition rate of 12.5 kHz and a stable pulse duration of 9.2 ns FWHM.

International audience; We present a new integrated optical sensor for absorption spectroscopy in a hostile environment, based on a nanochannel waveguide structure in glass. The nanochannel waveguide is made by bonding two ion-exchanged borosilicate glass wafers, one of them being etched by reactive ion etching to create a 100 nm deep fluidic channel. Typical fluid/light interaction factors of 2.3 % can be achieved inside a 7.4 pL volume of fluid, over a 550 nm bandwidth, surmounting evanescent wave sensors in terms of confinement efficiency and allowing spectrometric measurements. Absorption measurements have been performed on hexahydrate neodymium nitrate in nitric acid solutions of various concentrations leading to a minimum detectable absorption coefficient of 0.57 cm-1, which can be further decreased by implementing low bending-loss spiral-like nanochannel waveguides.

The realization of arrays of 15 distributed feedback lasers integrated on an Er-Yb-doped phosphate glass substrate is reported. A submicronic corrugated grating has been etched on a comb of Ag/sup +/-Na/sup +/ ion exchanged waveguides with varying diffusion aperture width. Robust single frequency emission spectrum are shown, closely gauged on the 25- and 100-GHz International Telecommunications Union grids around 1.535 /spl mu/m with a pump-power threshold of 14 mW and a slope efficiency of 5.7%.

International audience; High power single-mode pump laser diodes operating around 980nm are key components for Erbium-doped devices. Much effort is still currently devoted to improve both their wavelength stability and their achievable output power, while maintaining a stable single-mode operation.Usually, the emission wavelength is stabilized by an external Fiber Bragg Grating (FBG). This configuration requires free-space optics between the laser diode output facet and the fiber or a lensed fiber to ensure an efficient coupling efficiency. This constraint increases fabrication costs, dimensions and mechanical instabilities. Moreover, the maximum achievable output power is limited because a high optical power density can damage the laser facets. To increase the achievable output power, a solution consists in using Broad-Area Laser Diodes (BALD), which are multimode emitters that are composed of large active ribbons with width of some hundreds of micrometers. The objective is then to improve the beam quality by locking the BALD emission on its transverse fundamental mode. We propose in this article to insert an integrated adiabatic transition between the multimode laser and a single-mode FBG. This taper, made by ion-exchange in glass, provides a coupling efficiency of -22.0dB from the multimode laser emission to the single-mode fiber. An optical feedback of -34dB demonstrates the stabilization of the BALD spectrum at the Bragg wavelength. The spectrum of the device is characterized by a maximum side-mode suppression ratio of 35dB, a RMS spectral width of (0.16 ± 0.04) nm and a frequency shift with current of -12GHz/100mA.

International audience; 55 µm hybrid waveguide laser made by ion-exchange and wafer bonding," ABSTRACT Distributed Feed Back (DFB) lasers working in the third telecom window are essential for optical communications, eye-safe sensors and lab-on-chip devices. Glass integrated optics technology allows realizing such devices by using rare-earth doped substrates. Despite their good output power and spectral characteristic, DFB lasers still present some reliability issues concerning the Bragg grating protection. Moreover Erbium doped glasses are not compatible with the realization of passive optical functions. In order to solve the DFB lasers reliability issues and to ensure a monolithic integration between active and passive functions, we propose an hybrid-device architecture based on ion-exchange technology and wafer bonding. The Ag + /Na + ion-exchange in the silicate glass wafer is used to realize the passive functions and the lateral confinement of the electromagnetic field. Through a second ion exchange step, a slab waveguide is made on the Erbium-Ytterbium doped glass wafer. The Bragg grating is processed on the passive substrate and the two glasses are bonded. The potential of this structure has been demonstrated through the realization of a DFB hybrid laser with a fully encapsulated Bragg grating.

International audience; Mode-lock lasers have been studied a lot in the past years for producing pulses as short as possible. These devices have mostly been realized in bulk optics and they are consequently cumbersome and sensitive to vibrations. There are only a few studies on integrated optics mode-lock lasers, though this technology is very promising because of its stability, compactness and the possibility to integrate several functions on a single chip. In this paper, we present an ion-exchange passively mode-locked laser in dissipative soliton operation. One of the key characteristics of this structure is its mechanical stability. Indeed, no bulk optics is needed because the saturable absorber is hybridized on the top of the waveguide in order to interact with the evanescent part of the guided mode. Indeed, the device that has been obtained is composed of an ion-exchanged single mode waveguide realized in a Neodymium doped phosphate glass. The laser feedback is produced by a Fabry-Perot cavity realized with two multilayers dielectric mirrors stuck on the waveguides facets. We implemented a bis(4-dimethylaminodithiobenzil)nickel (BDN) dye included in a cellulose acetate thick film, which presents a saturable absorber behaviour around 1.06 µm. With this structure, pulses with repetition rates of 3.3 GHz and a single mode output have been measured. Moreover, the use of an autocorrelation setup allowed us measuring picosecond pulse durations.

International audience; In the framework of the “Integrated Optics” project, single-mode RIB waveguides for both [6–11µm] and [10–20µm] spectral bands were developed in order to manufacture modal filters for spatial interferometry. In this paper, the different steps of the fabrication of such components are described and the first results in term of light guiding and modal filtering are presented.

The hybrid integration of optical amplifier modules requires the development of a new kind of pump/signal duplexers. In this letter, a new structure highly compatible with pump diode waveguides (λ = 0.98 μm), optical fibers (λ = 1.55 μm), and hybrid erbium-doped waveguide amplifiers is proposed. The device, based on a vertically integrated asymmetric Y-junction, has been realized by cascading three ion exchanges on a glass substrate. Bandwidth of more than 200 nm around the two working wavelengths has been demonstrated with isolations between the two outputs reaching (21 ± 0.4) dB at λ = 0.98 μm and (44 ± 0.4) dB at λ = 1.55 μm and low losses.

The search for Earth-like exoplanets, orbiting in the habitable zone of stars other than our Sun and showing biological activity, is one of the most exciting and challenging quests of the present time. Nulling interferometry from space, in the thermal infrared, appears as a promising candidate technique for the task of directly observing extra-solar planets. It has been studied for about 10 years by ESA and NASA in the framework of the Darwin and TPF-I missions respectively. Nevertheless, nulling interferometry in the thermal infrared remains a technological challenge at several levels. Among them, the development of the "modal filter" function is mandatory for the filtering of the wavefronts in adequacy with the objective of rejecting the central star flux to an efficiency of about 105. Modal filtering takes benefit of the capability of single-mode waveguides to transmit a single amplitude function, to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible. The modal filter may either be based on single-mode Integrated Optics (IO) and/or Fiber Optics. In this paper, we focus on IO, and more specifically on the progress of the on-going "Integrated Optics" activity of the European Space Agency.

In the framework of optical telecommunication systems, many functions are integrated on the same substrate. Nevertheless, one of the most important, such as isolation, is achieved using discrete components. It is based on magnetic materials which are always difficult to integrate with classical technologies. This is due to the annealing temperature of magnetic materials. In this paper we present another way for the realisation of such components. We use a dip coating process to report a magnetic nanoparticles doped silica layer on ion-exchanged glass waveguide. The advantages of this method is discussed and we demonstrate its compatibility with ion-exchanged technology. By varying the refractive index of the layer, we can adjust the interaction between the waveguide and the magneto-optical layer.

International audience; In this paper, we present the development of a laser source for a LIDAR application. This sensor is proposed as a standby instrument to provide a way to measure some aircraft air data such as the air speed. Although such systems already exist, none of them are based on an optical measurement. Thus, the use of a LIDAR would provide a backup channel with different failure modes than existing systems. Our LIDAR system allows determining the air speed through Doppler measurement at a wavelength of 1.55 µm on aerosol particles present around the aircraft. The core of this device is a glass integrated optics continuous DFB laser. Its performances in term of single-frequency, stability, noise and linewidth are assessed in order to ensure the correct operation of the LIDAR system.

Modal filtering is based on the capability of single-mode waveguides to transmit only one complex amplitude function to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible in a nulling interferometer. In the present paper we focus on the progress of Integrated Optics in the thermal infrared [6-20μm] range, one of the two candidate technologies for the fabrication of Modal Filters, together with fiber optics. In conclusion of the European Space Agency's (ESA) "Integrated Optics for Darwin" activity, etched layers of chalcogenide material deposited on chalcogenide glass substrates was selected among four candidates as the technology with the best potential to simultaneously meet the filtering efficiency, absolute and spectral transmission, and beam coupling requirements. ESA's new "Integrated Optics" activity started at mid-2007 with the purpose of improving the technology until compliant prototypes can be manufactured and validated, expectedly by the end of 2009. The present paper aims at introducing the project and the components requirements and functions. The selected materials and preliminary designs, as well as the experimental validation logic and test benches are presented. More details are provided on the progress of the main technology: vacuum deposition in the co-evaporation mode and subsequent etching of chalcogenide layers. In addition, preliminary investigations of an alternative technology based on burying a chalcogenide optical fiber core into a chalcogenide substrate are presented. Specific developments of anti-reflective solutions designed for the mitigation of Fresnel losses at the input and output surface of the components are also introduced.

In the mid 80's, the doping of optical fiber's core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in-line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by ion exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a BDN saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the CW operation of the laser with an undoped cladding. We show that for a 3.5-μm wide, 1.4-cm long waveguide realized by a silver-sodium ion exchange, a 6 mW output has been achieved by creating a Fabry-Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN doped layers are presented. It is shown that a proper selection of the hybrid guiding structure and saturable absorber concentration entail an excess absorption ranging from 1 to 10 dB/cm at zero flux. Finally, results on Q-switched behavior are presented. Optical pulse duration of 2-ns (FWHM) was obtained with repetition rates ranging from 5 to around 50 kHz for a 22 W pulse peak power.

In the mid 80s, the doping of optical fibers’ core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by an ion-exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a bis(4-dimethylaminodithiobenzil)nickel (BDN) saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the continuous wave (CW) operation of the laser with an undoped cladding. We show that for a 3.5 μm wide, 1.5 cm long waveguide realized by a silver–sodium ion-exchange, a 6 mW output has been achieved by creating a Fabry–Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN-doped layers are presented. It is shown that a proper selection of the hybrid guiding condition and saturable absorber concentration entail a non-saturated excess absorption of 3.4 dB/cm. Finally, we present the results we obtained on the Q-switched behaviour of the laser. Indeed a repetition rate of 330 kHz is achieved for a pulse energy of 10 nJ and a peak power of 1 W.

Ion-exchange on glass is now a mature integrated optics technology. Indeed, many devices such as wavelength multiplexers, splitters, optical amplifiers, lasers or sensors have been already realized. The challenge now is to integrate all these functions on a single chip. Two different paths can be used to achieve this goal: the first one consists of a reduction of the waveguides’ dimensions by an increase of the refractive index change, whereas the second one, which is addressed in this paper, is based on the realization of multilayered devices. Because ion-exchange on glass allows manufacturing either surface or buried waveguides, this technology is well adapted for 3D integration. However, to realize integrated optical devices with two different layers, it is mandatory to prevent any parasitic light transfer between them. This condition can be fulfilled if the top and bottom waveguides are sufficiently separated. In this article, we present the development of ion-exchanged waveguides deeply buried into a glass substrate and their application to 3D integrated devices. Deeply buried waveguides have been realized by means of a two steps silver–sodium ion-exchange on a dedicated custom made silicate glass. First, a thermal ion-exchange has been carried out at 330 °C during 2 min in a 0.8NaNO3–0.2AgNO3 molten salt in order to create the core of the waveguide. Then, this core has been buried into the glass substrate by applying an electric field of 450 kV/m during 1 h 30 min in a sodium nitrate solution at 260 °C. The obtained waveguide has been measured to be 22 μm under the glass surface. It is singlemode at λ = 1.55 μm. In order to prove the good isolation between this waveguide and the surface, a top layer has been added to the device by the realization of surface channel waveguides through a thermal ion-exchange performed in a 0.8NaNO3–0.2AgNO3 molten salt at 330 °C during 2 min. The near-field observation of the device output has shown no coupling between the top and bottom layers demonstrating therefore the feasibility of 3D integrated optical devices by means of ion-exchange on glass.

International audience; Ion-exchange on glass has been successfully used for more than twenty years to realize integrated optics devices such as wavelength multiplexers, splitters, optical amplifiers, lasers or sensors. One of the major issue is today to integrate more functions on a single chip which is usually realized be reducing the dimensions of the waveguides. Nonetheless this reduction is intrinsically limited by the maximum index variation achievable. For this reason, we propose and investigate in this article the realization of 3D structures where waveguides are integrated vertically instead of horizontally. Based on the selective burial of ion-exchanged waveguides and the cascading of multiple ion-exchanges, the realization of ”vertical” asymmetric and symmetric Y-junctions have been investigated theoretically.

With the development of optical telecommunication systems, there has been a huge work realized on integrated optics. Indeed, today several technologies are available to realize integrated devices. Among them, there is ion-exchange on glass which has been successfully used for more than twenty years to realize integrated optics devices such as wavelength multiplexers, splitters, optical amplifiers, lasers or sensors. In this paper we review the advances made by integrated optics on glass and we try to position this technology towards other technologies.

Aims: In the context of space interferometry missions devoted to the search of exo-Earths, this paper investigates the capabilities of new single mode conductive waveguides at providing modal filtering in an infrared and monochromatic nulling experiment; Methods: A Michelson laser interferometer with a co-axial beam combination scheme at 10.6 microns is used. After introducing a Pi phase shift using a translating mirror, dynamic and static measurements of the nulling ratio are performed in the two cases where modal filtering is implemented and suppressed. No additional active control of the wavefront errors is involved. Results: We achieve on average a statistical nulling ratio of 2.5e-4 with a 1-sigma upper limit of 6e-4, while a best null of 5.6e-5 is obtained in static mode. At the moment, the impact of external vibrations limits our ability to maintain the null to 10 to 20 seconds.; Conclusions: A positive effect of SM conductive waveguide on modal filtering has been observed in this study. Further improvement of the null should be possible with proper mechanical isolation of the setup., Comment: Accepted in A&A, 7 pages, 5 figures

We present the fabrication and characterization of two high concentration Yb3+-Er3+ co-doped double clad phosphate glass optical fibers (named A and B for short) manufactured by preform drawing, with the preform being obtained by the rod-in-tube technique. Optical amplification was demonstrated by core pumping 27 mm of fiber A (7/25/70 µm and NA = 0.17 between core and inner cladding) with a laser diode at 976 nm, achieving a 10.7 dB internal gain, i.e., 4.0 dB cm-1, for small signal input at 1535 nm. Amplification was also demonstrated in a cladding-pumped counter propagating configuration using both fibers A and B (12/48/140 µm and NA = 0.08). A maximum internal gain of 18.5 dB was achieved with 8 cm of fiber B, corresponding to an amplification of 2.3 dB cm-1, for small signal input at 1535 nm.

This paper presents the development and tests in the thermal infrared of Integrated Optics (IO) technology in preparation of ESA's space mission Darwin . This mission aims to detect and characterize earth-like planets orbiting solar-type stars, using nulling interferometry in the spectral range 6 - 20 μm. Since typically 1:1e6 rejection of starlight is required, wavefront modal filtering is mandatory. Thus, mid-infrared single-mode IO is being developed in the framework of the ESA-funded "Integrated Optics for Darwin" project. Beyond its wavefront filtering capabilities, an IO component may support various optical functions, and is thus likely to ease instrumental design. This paper addresses the manufacturing process and the characterization tests results of newly developed IO devices. Investigated solutions are dielectric waveguides based on Chalcogenide glasses and Hollow Metallic Waveguides. In a first phase, the pre-selected technological solutions were validated and modal behavior of the manufactured devices was demonstrated, both through polarization and spectral analysis. Preliminary nulling ratios up to 5000 have been obtained with an IO modal filter in the 6 - 20 μm range. In a second phase of the project, the development of more complex IO functions was attempted. The methods used to validate the waveguide behavior and interferometric capabilities are also discussed. After achieving 1:1e5 polychromatic extinctions with similar solutions in the near IR, the presented results further underline the credibility of a mid-infrared IO concept for Darwin.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Thanks to the maturing of rare-earth highly-doped materials, erbium-doped waveguide amplifiers (EDWAs) present a compact alternative to fiber amplifiers. While ion-exchanged EDWAs implemented on glass substrates provide the best passive characteristics, EDWAs based on thin films technologies offer a higher integration and amplification efficiencies. This paper proposes the realization of EDWAs in a new configuration which combines all these advantages. Indeed, this optical amplifier consists of an erbium/ytterbium-codoped glass guiding layer reported on an ion-exchanged strip formed on a passive glass substrate. The electromagnetic principle of operation of this hybrid structure is presented as well as simulations of its behaviour. Then, the realization and characterization of two different hybrid amplifiers is presented: the first one, based on a Tl + /K + ion-exchanged strip provides a high gain coefficient of 3.66 ± 0.25 dB/cm; whereas the second one, realized with a Ag + /Na + ion-exchanged strip, presents a good coupling efficiency with optical fibers, which allows the measurement of a 1 dB net gain.

Stellar interferometry is an old technique (first successful measurement of Titan diameter by Michelson in 1890), which have recently been dramatically improved by the implementation of integrated optical devices. The technique, consisting in combining coherently several beams coming from distinct telescopes, allows to reconstruct images with a very high angular resolution, typically 10 times better than the diffraction limit of the biggest telescopes on Earth and about 20 times better than the Hubble space telescope. During the last few years, LETI, in collaboration with IMEP (Institut de MicroElectronique et Photonique) and LAOG (Laboratoire d'Astrophysique de l'Observatoire de Grenoble) has developed several components for stellar interferometry, either using its well-established silica on silicon technology, or developing a new silicon technology for mid-infrared metallic hollow waveguides adapted for the ESADARWIN mission. This paper will present the latest developments made by LETI in this field, describing the silicon technologies involved, the realized devices as well as their behaviour on laboratory set-ups or on the sky.

This paper presents the work achieved for the manufacturing and characterization of first single-mode waveguides to be used as modal filters for nulling interferometry in the mid-infrared range [4-20 um]. As very high dynamic range is mandatory for detection of Earth-like planets, modal filtering is one of the most stringent instrumental aspects. The hollow metallic waveguides (HMW) presented here are manufactured using micro-machining techniques. Single-mode behavior has been investigated in laboratory through a technique of polarization analysis while transmission features have been measured using flux relative comparison. The single-mode behavior have been assessed at lambda=10.6 um for rectangular waveguides with dimensions a=10 um and b, 10 pages, 6 figures, accepted in A&A

To detect earth-like planets orbiting around solar-type stars in the mid-infrared spectral range, a typical rejection ratio of 10 6 of the stellar flux must be achieved. Space missions like Darwin/TPF aim at achieving such contrasts using nulling interferometry between 4 μm and 20 μm. The instrumental constraints on beam combination, spatial filtering, intensity and phase mismatches must then be accurately considered. This paper presents the first characterization results of mid-infrared waveguides for integrated optics (IO) developed in the frame of an ESA contract. Taking into account the scientific achievements already obtained with IO components in the near infrared range, results demonstrate that these technologies can also be used for future nulling devices as an alternative to bulk optics instrumentation in the mid-infrared spectral range. Good waveguiding behaviour has been obtained on dielectric waveguides based on Chalcogenide or Zinc Selenide glasses and Hollow Metallic Waveguides. The single-mode behavior, spatial filtering and polarization control capabilities of the hollow metallic channel waveguides have been also demonstrated. This paper focuses on the methods used to validate the waveguide behaviour and the first laboratory results obtained with the different technologies used in the mid-infrared.

High coherence glass DFB lasers emitting in the 1550 nm window are useful for many applications, including eyesafe sensors and DWDM telecommunication systems. One of the key characteristic of lasers designed for sensor or telecommunications applications is their monomode behaviour. A standard DFB laser indeed emits two wavelengths located at both sides of the grating stop band. A quarter-wave phase shift is thus required in the center of the grating in order to make a single mode laser. In this paper, we present a new kind of phase shift, that was initially developped for semiconductor lasers but never applied to glass or fiber optics lasers. The main advantage of this technique is that the phase shift is realized during the waveguide photolithography process so that there is no need of any additionnal step. Moreover, its design ensures that the value of the phase shift can be very accurately set, which enables to realize a grating cavity with a unique lasing wavelength. Both theoretical and experimental results on these new phase shifted lasers are presented and a SMSR of more than 50dB is presented.

International audience; We present the design of an innovating integrated planar structure adapted for intensity or phase measurements. It is based on the evanescent prism decoupling of the optical signal from a waveguide used as the sensing element. The device is formed by successive thin film sputtering deposition. A TiO2 crystalline layer forms the gas sensing element from which light is coupled out by a planar high refractive index prism. We experimentally validate the structure.

Thanks to the maturing of rare-earths highly-doped materials, erbium-doped waveguide amplifiers (EDWAs) present a compact alternative to fibre amplifiers. While ion-exchanged EDWAs implemented on glass substrates provide the best passive characteristics, EDWAs based on thin films technologies offer higher integration degree and amplification efficiencies. This paper proposes the realization of an EDWA in a new configuration which combines all these advantages. Indeed, this optical amplifier consists of an erbium/ytterbium-codoped glass guiding layer reported on an ion-exchanged strip formed on a passive glass substrate. The electromagnetic principle of operation of this hybrid structure is presented. Then, all technological steps of realization are detailed including the report of the active layer by a low-temperature wafer bonding process. Finally, passive and active characterizations allow demonstrating the single mode operation and the amplification efficiency of the hybrid waveguide. Indeed, a high gain coefficient of 3.66±0.25 dB/cm is obtained in the 1.16-cm-long hybrid amplifier.