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Rare-earth ion doped potassium yttrium double tungstate, RE: KY(WO4)(2), is a promising candidate for small, power-efficient, on-chip lasers and amplifiers. There are two major bottlenecks that complicate the realization of such devices. Firstly, the anisotropic thermal expansion coefficient of KY(WO4)(2) makes it challenging to integrate the crystal on glass substrates. Secondly, the crystal layer has to be, for example, < 1 mu m to obtain single mode, high refractive index contrast waveguides operating at 1550 nm. In this work, different adhesives and bonding techniques in combination with several types of glass substrates are investigated. An optimal bonding process will enable further processing towards the manufacturing of integrated active optical KY(WO4)(2) devices. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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.

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.

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.

This paper deals with an experimental non-destructive technique for the measurement of polarization behavior of integrated optical waveguides. It is based on a high resolution polarimeter associated to an ellipsometric-type calibration which allows determining the full state of polarization of the output light. A magneto-optic perturbation is also added to generate TE/TM mode beating, whose spatial period is directly linked to the modal TE/TM birefringence. This equipment is first qualified by the measurement of modal birefringence in totally or partially buried ion exchanged waveguides. The results show that the value of the birefringence varies as a function of the diffusion aperture width or with the burying depth. By adding a magneto-optical cover layer, consisting in magnetic nanoparticles doped silica matrix obtained by a sol gel process 1, we evidence a huge increase of the beating magnitude and a decrease of the modal birefringence.

Ion-exchange technology on glass has been successfully used for more than 20 years to realize dependable and low-cost passive and active integrated optic devices on silicate or phosphate glasses for the optical telecommunication systems operating around λ = 1.5 μm. However, the recent developments of integrated optics instruments for astronomical interferometers or biological sensors have required an increase of the devices operation range towards the mid-infrared. For these reasons, we present in this paper the development and the realization of single-mode waveguides by means of a binary ion-exchange on a germanate glass (BGA-G115 form Kigre Inc.) which transparency window reaches λ = 4 μm. A complete study of the silver ion diffusion in this glass matrix has been performed allowing the determination of silver and sodium ion diffusion coefficients as well as the value of the maximum refractive index change. Using these data, simulations were carried-out showing that an ion-exchange of 90 min in a 0.03AgNO 3 –0.97NaNO 3 molten salt at a temperature of 330 °C would allow the realization of single-mode channel waveguides at λ = 1.55 μm. To demonstrate this on BGA-G115, a specific technological process based on the deposition of a polysilicon masking layer has been implemented. Single-mode channel waveguides, with a 2.5 μm diffusion window width, have thus been realized and characterized at the wavelength of 1.55 μm. Modal size has been measured to be 10 ± 1 μm × 7 ± 1 μm for propagation losses of 1.2 ± 0.5 dB/cm for a 2 ± 0.1 cm long device.

The integration of magneto-optical materials to realize non-reciprocal functions is still a difficult problem, because classical magneto-optical materials require an annealing temperature as high as 700°C. In this framework, this study shows how it is possible to realize efficient magneto-optical mode converter using the association of a magnetic nanoparticles silica/zirconia composite with an ion-exchanged glass waveguide. Using a sol gel process, a silica/zirconia matrix is doped by magnetic nanoparticles (CoFe2O4) and coated on a glass substrate containing straight channel waveguides made by a silver/sodium ion exchange. The extremities of the guides were previously buried using electric field-assisted burial in order to facilitate light injection. Soft annealing (90°C) and UV treatment, both compatible with the ion exchange process, have been implemented to finalize the magneto-optical film. Depending on the amount of nanoparticles in the composite, on the spatial distribution of the field in the guide and on the modal birefringence of the hybrid structure, the TE-TM conversion varies from several degrees to several tens of degrees.

In this letter, we present the design, fabrication, and characterization of a broadband polarization splitter working in the 1550-nm transmission window. The device is an asymmetric Y-junction realized by Ag+/Na+ ion exchange on glass. The transverse electric (TE) output branch of the device filters out the residual transverse magnetic (TM) mode by radiation. Measurements show cross-talks better than (31.1±0.4) dB in TE and better than (32.7±0.4) dB in TM mode over a 70-nm bandwidth limited by the characterization source. Optimal values of, respectively, (33.6±0.4) dB and (37.2±0.4) dB were measured at 1540 nm. At this wavelength, the insertion losses are, respectively, (6.0±0.4) dB and (5.5±0.4) dB in TE and TM modes while the function losses are (0.65±0.12) dB and (0.35±0.12) dB, respectively.

This paper deals with an experimental nondestructive technique for the measurement of modal birefringence of integrated optical waveguides. The method is based on a magneto-optical perturbation technique combined with a highly sensitive polarimeter. Magneto-optical modal conversion, through the Verdet constant of the waveguides, and its dependence on the perturbation length are discussed. In this paper, the practical application of this equipment is proposed for the measurement of modal birefringence in totally or partially buried ion exchanged waveguides.

We propose and demonstrate a new integrated polarization splitter made by ion exchange on glass operating at a wavelength of 1.55 μm. The design is based on an asymmetric Y-junction with one output branch supporting only the TE mode. Cross-talk lower than -30.0 dB in TM mode has been achieved over a wavelength range of 80 nm. Values lower than -10.0 dB for the TE mode were demonstrated over the same bandwidth with an optimum of -19.8 dB at 1.54 μm. The experimental results are in good agreement with simulations. We measured insertion losses of 6.5 dB in both modes.

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.

The integration of magneto-optical materials with classical technologies being still a difficult problem, this study explores the possibility to realize a mode converter based on a hybrid structure. A composite magneto-optical layer made of a silica/zirconia matrix doped by magnetic nanoparticles is coated on the top face of ion-exchanged glass waveguides. Optical characterizations that have been carried out demonstrated the efficiency of these hybrid structures in terms of lateral confinement. Furthermore, TE to TM mode conversion has been observed when a longitudinal magnetic field is applied to the device. The amount of this conversion is analysed taking into account the magneto-optical confinement and the modal birefringence of the structure.

To overcome the difficult problem of the integration of magneto-optical materials with classical technologies, our group has developped a composite magneto-optical material made of a hybrid organic-inorganic silica type matrix doped by magnetic nanoparticles. Thin films of this material are obtained through a soft chemistry sol-gel process which gives a full compatibility with an integration on glass substarte. Due to an interesting magneto optical activity (Faraday rotation of 310°/cm) several magneto-optical functionnalities have been realized. A thin film of such composite material coated on a pyrex™ substrate acts as non-reciprocal TE/TM mode converter. An hybrid stucture made of a composite film coated on an ion-exchanged glass waveguide has been realized with a good propagation of light through a hybrid mode. Finally, the sol gel process has been adapted in order to obtain 3D inverse opals which should behave as magnetophotonic crystals. Transmittance curves reveal the photonic band gap of such opals doped with magnetic nanoparticles.

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.

Ion-exchanged devices on glass have been successfully used to realize passive and active integrated optic devices for sensor and telecom applications. Nowadays, research is focused on the reduction of the chip dimensions with an increase of the number of different function integrated. In this paper we present how the use of two stacked optical layers can allow realizing efficient and compact pump duplexer for ion-exchanged hybrid erbium doped waveguide amplifier. Indeed our complete theoretical study of the device shows that excess losses lower than - 0.1 dB and crosstalk lower than -20 dB can be achieved.

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.

In this letter, the fabrication and characterization of a broadband 980-nm/1550-nm wavelength (de)multiplexer is described. This device is adapted for pump/signal multiplexing in erbium-doped waveguide amplifiers. The structure chosen is a segmented asymmetric Y-junction, which can be fabricated with one masking level using silver-sodium ion-exchange on a silicate glass substrate. The nonresonant behavior of the Y-junction allows a wideband multiplexing with isolations increasing from (9.7plusmn0.1) dB at 1500 nm to (15plusmn0.1) dB at 1630 nm and (26plusmn1) dB at 980 nm. The total insertion losses are (2.8plusmn0.1) dB at 980 nm and (3.3plusmn0.2) dB between 1500 and 1630 nm

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.

Broadband wavelength (de)multiplexers play a key role in different fields of integrated optics. In particular, the development of Erbium Doped Waveguide Amplifiers (EDWA) requires efficient integrated pump/signal multiplexers. In this article, the design and the realization of a 980 nm/1550 nm wavelength multiplexer based on a segmented asymmetric Y junction made by silver/sodium ion exchange on glass is discussed. We first present the behavior of an asymmetric Y junction, in order to describe its use as a wavelength (de)multiplexer. Then, the index averaging principle of a segmented waveguide is detailed, as well as its application in the design of one of the asymmetric Y junction branches. The design of a segmented asymmetric Y junction is then described, as well as its BPM simulations results. They show isolation of 33 dB at 980 nm and 25.6 dB at 1550 nm with excess losses of 2.6 dB at 980 nm and 1.3 dB at 1550 nm. In a second time, we present the realization of this component using a Silver/Sodium ion-exchange on glass. For λ = 980 nm, the isolation measured is (31 ± 1) dB, and in the third communication window, the isolation increases from (11.5±0.25) dB at λ = 1500 nm to (15.5±0.25) dB at λ = 1600 nm. The broadband operation is only limited by the modal characteristics of the waveguides composing the junction and ranges from 1500 nm to 1650 nm. Total insertion losses measured at 980nm are (2.63±0.1) dB. Around 1550 nm, losses vary from (3.6 ± 0.1) dB at the 1500 nm wavelength to (4.6 ± 0.1) dB at 1600 nm.

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.

In this paper, the realization and characterization of periodic segmented waveguides made by ion-exchange on glass is presented as well as their application to polarizers and wavelength duplexers. Segmented waveguides are of major interest for integrated devices because they allow tailoring the refractive index without changing the technological parameters. Indeed, a segmented waveguide, which is composed of a periodic succession of guiding and non-guiding zones, can be considered as a classical waveguide with a core refractive index that ranges from the segmented core to the substrate ones, depending on the segmentation ratio. Through this way, it is thus possible to avoid the use of more complex techniques that require a double-step lithography process. In the first part of the article, surface segmented waveguides made by ion-exchange on glass are studied and a linear relationship between the segmentation duty cycle and the maximum core refractive index of an equivalent continous waveguide is demonstrated. A simple correction on the duty cycle is needed to take into account the longitudinal diffusion. After a presentation of its principle of operation, in the second part of the article, we propose the realization and characterization by means of segmented waveguide of a polarizer with more than 30dB of extinction ratio at λ = 1550nm. Finally, the design and first results obtained on a duplexer based on an asymmetric segmented Y-junction are presented.

International audience; These last years, the growth of data traffic has increased the interest for broadband integrated optic devices. Their applications include, for example, the fiber communications on a single fiber by adding the transmission capacity of two optical telecommunication windows for Local Area Networks (LAN) and Wide Area Networks (WAN) or by combining pump and signal wavelenghts in rare earth doped intergrated optical amplifiers. A promising technology to realize those devices is ion-exchange on glass. Indeed, it allows the integration of different functions in a glass substrate with efficient results and a better compatibility in fiber systems with a low cost. We propose in this paper an original broadband duplexer based on a leaky structure. First, the physical principle of the component is explained. The core of the structure is a leaky zone which involves a non-resonant coupling and ensures a broadband spectral behavior to the component. Then, the broadband duplexer is presented and the focus is specially made on the improvement of the outputs crosstalk through the suppression of parasitical back reflections. Theoretical optimization and validation by simulations are presented. Finally, perspectives of this work are proposed.

The realisation and characterisation of periodic segmented waveguides made by Ag+/Na+ ion-exchange on glass is presented. In particular, the averaging effects provided by the segmentation are analysed using the measurement of the cutoff wavelengths of the fundamental mode. Numerical calculations are used to evaluate the equivalent index contrast of a continuous waveguide from cutoff wavelength. It is found that the model predicting the index averaging effect of periodically segmented waveguides is valid if the duty cycle of the segmented waveguide is corrected by a term that takes into account the longitudinal ion diffusion.

In the last few years, the growth of data traffic has increased the interest in broadband integrated optical devices. Their applications include, for example, a possibility of bidirectional fiber communications in a single fiber, which is achievable by adding the transmission capacity of two optical telecommunication windows for local area networks (LAN) and wide area networks (WAN) or by combining pump and signal wavelengths in rare earth-doped integrated optical amplifiers. A promising technology to realize those devices is ion exchange in glass. This allows the integration of different functions on a glass substrate with efficient results and a better compatibility in fiber systems at a low cost. We propose an original broadband duplexer based on a leaky structure, which involves a nonresonant coupling and ensures a broadband spectral behavior. The broadband duplexer is first presented, and the focus is specially made on the improvement of the output cross talk through the suppression of parasitical back reflections. Theoretical optimization and validation by simulations follow. The spectral response of the optimized structure displays two duplexing bands of at least 200 nm in width with a total output channels' isolation within 0.6- to 0.8-μm range, and a better than 15-dB isolation level within 1.2- to 1.4-μm range, with a maximum of 24-dB isolation at 1.31 μm.