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We demonstrate a clear eye-diagram at 36 Gb/s of a BiCMOS driver directly wire-bonded to an InP electro-absorption modulator (EAM) both fabricated through foundry platforms. The driver is fabricated in a 0.25 μm SiGe:C BiCMOS technology and delivers a maximum of 2 Vp-p amplitude when single-ended. The driver is DC-coupled to the modulator, simplifying the electronic-photonic assembly. The EAM operates in the L-band at 1590 nm, with a DC bias set at –1.6 V for on-off keying non-return to zero modulation. We measure the operation from 10 to 40 Gb/s, recording the dynamic extinction ratio from 5 to 3 dB, respectively. The use of foundry platforms does not require any fabrication process change and offers a wide spectrum of high-performance photonic-electronic integrated circuits.

In this work we study the limits of miniaturization of a 90-degree hybrid coupler working in the L, C and S bands, with respect to a number of performance parameters aimed at its application for balanced detection. We investigate the main effects responsible for the degradation of the performance of the devices during miniaturization, and establish the minimal dimension that such devices can have without significant degradation for photonic applications such as balanced detection. The miniaturized device in InP generic technology has a footprint of only 2200μ m2 , more than 5 times smaller than the conventional device used as reference. The scaling approach is based on the use of the number of propagating modes which are sustained in both the miniaturized MMI and port waveguides as scaling parameters. This approach allows us to generalize the miniaturization problem from a specific platform and offers a methodology which is flexible and transferable to multiple platforms. We tested the scaling methodology based on the number of modes in other platforms commonly used in integrated photonics, such as Si/SiO2(SOI), TriPleX or polymer platforms, obtaining comparable results and proving the universality of our approach, finally we performed a fabrication tolerance analysis of the miniaturized devices.

In this paper, an on-chip optical circulator on the InP-membrane-on-Si (IMOS) platform is demonstrated. The circulator is composed of two multi-mode interferometers (MMIs), four polarization converters (PCs), and a Cerium-doped Yttrium Iron Garnet (Ce:YIG) die. The Ce:YIG die is adhesively bonded on the InP membrane via a 125-nm thin bonding layer. Nonreciprocal phase shift (NRPS) is employed in the presence of a transverse magnetic field. The device works as a 4-port optical circulator with a maximum optical isolation of 27.0 dB and a minimum optical isolation of 18.6 dB for the TE mode. The measured optical isolation bandwidth is 0.12 nm. Two methods are proposed in order to improve the optical isolation bandwidth.

The self-spiking behavior of an integrated saturable absorber and gain section laser fabricated in an InP technology platform is analyzed. The gain, absorber and intensity dynamics are first inspected using the normalized Yamada model. This model shows excitable behavior as well as the relative refractory period, both of which are also present in biological neurons. Measurements of a two-section laser show irregular spike generation on the millisecond timescale, with a saturable absorber voltage controlled spike density. From our simulations, and from the quasi-random character and millisecond timescale at which these pulses occur, we conclude the laser is triggered by noise, an important characteristic in the operation of biological neurons. Simulations of the laser around the excitability threshold using a newly proposed model with an optical noise term show qualitatively similar self-spiking behavior as measured.

In this paper, we present a flip-chip bonding concept for InP die on SiN-based TriPleX carrier using laser soldering. The InP die and SiN-based TriPleX carrier include the metalization patterns for commonly used photonic integrated circuit reference designs. Two laser soldering schemes were investigated: (1) using a laser wavelength where silicon is highly transmissive (through-silicon laser soldering) and (2) using a laser wavelength where silicon is not transmissive (heat-conduction laser soldering). We demonstrated a 4.0 mm × 4.6 mm InP die with 58 electrical connections flip-chip bonded on a 16.0 mm × 8.0 mm SiN-based TriPleX carrier. Comparison experiments were carried out including solder reflow and shear force tests. Both schemes showed reliable electrical interconnects that meet MIL-STD 883 standards. Especially, the through-silicon soldering showed faster soldering time, lower power for solder reflows, and less thermal impact which is therefore preferred over heat-conduction soldering. This concept is promising for a high-density, reliable interconnect of hybrid packaging of InP on SiN-based photonic integrated circuits, in particular large photonic dies.

In monolithic photonic integrated circuits (PICs), an optimized active/passive integration is needed to provide efficient coupling and low amount of interface reflections between amplifiers and passive components. A 1300 nm semiconductor optical amplifier (SOA) on InP substrate and optimized for butt-joint reflections is investigated. Material performance were assessed from measurements of broad area lasers. Room temperature operation reveals 1.2 W single facet output power with threshold current around 100 A/cm2 per well. Characteristic temperatures of T0 = 75 K and T1 = 294 K were obtained. A compact model description of the SOA, suitable for the design of PICs and rate equation analysis, was applied to parametrize the unsaturated gain measurements. Current injection efficiency of 0.65, transparency carrier density of 0.57 1018 cm−3, and free carrier absorption losses up to 15 cm−1 were extracted from fitting the data. The model is verified with measurements of optical gain saturation. A modal gain of 15 dB for a 600 μm long narrow ridge SOA leads to output saturation power higher than 30 mW at 7 kA/cm2. This building block contributes to the development of an InP monolithic integration technology in the 1300 nm range, which can enable the use of photonic integrated circuits in many kind of applications.

We introduce a hybrid plasmonic-photonic device for on-chip all-optical switching and reading of ferrimagnet bits with perpendicular magnetic anisotropy in a racetrack spintronic memory, coupled onto an indium phosphide waveguide. The device comprises V-shaped gold plasmonic nanoantennas coupled with a photonic crystal cavity, which enables switching and reading of the magnetic state of nanoscale bits by enhancing the absorbed energy density and polar magneto-optical Kerr effect locally. Using a finite-difference time-domain method, we show that our device can switch and read targeted bits down to 100 nm in the presence of oppositely magnetized background regions in the racetrack with widths up to 120 nm, clearly outperforming a bare photonic waveguide. Our hybrid device provides the missing link between integrated photonics and nanoscale spintronics by tackling the challenges of nonlinear absorption in the waveguide, weak magneto-optics, and size mismatch, leading to the development of ultrafast and energy-efficient advanced on-chip applications.

Electro-optic (EO) modulation is a well-known and essential topic in the field of communications and sensing, while ultrahigh modulation efficiency is unprecedentedly desired in the current green and data era. However, dramatically increasing the modulation efficiency is difficult in conventional mechanisms, being intrinsically limited by the monotonic mapping relationship between the electrical driving signal and modulated optical signal. To break this bottleneck, a new mechanism termed phase-transition EO modulation is revealed from the reciprocal transition between two distinct phase planes arising from the Hopf bifurcation, being driven by a transient electrical signal to cross the critical point. A monolithically integrated mode-locked laser is implemented as a prototype, strikingly achieving an ultrahigh modulation energy efficiency of 3.06 fJ bit−1 improved by about four orders of magnitude and a contrast ratio exceeding 50 dB. The prototype is experimentally implemented for radio-over-fiber communication and acoustic sensing. This work indicates a significant advance on the state-of-the-art EO modulation technology and opens a new avenue for green communication and ubiquitous sensing applications.

We report a versatile method for improving post-bonding wafer alignment accuracy and BCB thickness uniformity in stacks bonded with soft-baked BCB. It is based on novel BCB-based micro-pillars that act as anchors during bonding. The anchor structures become a natural part of the bonding interface therefore causing minimal interference to the optical, electrical and mechanical properties of the bonded stack. We studied these properties for fixed anchor density and various anchor heights with respect to the adhesive BCB thickness. We demonstrated that the alignment accuracy can be improved by approximately an order of magnitude and approach the fundamental pre-bond alignment accuracy by the tool. We also demonstrated that this technique is effective for a large range of BCB thicknesses of 2–16 μm. Furthermore we observed that the thickness non-uniformities were reduced by a factor of 2–3 × for BCB thicknesses in the 8–16 μm range.

The immense growth of data traffic that traverses modern networks, calls for immediate solutions to tackle the challenges that arise in terms of speed, capacity, cost and energy efficiency. This manuscript outlines the key technological aspects of the PICaboo project, that aims to develop novel building blocks and photonic integrated circuits for the next generation of optical metro and access networks enhanced with optical signal processing functionalities exploiting the generic foundry model approach.

In photonic integrated circuits (PICs), optical isolators and circulators are essential to prevent lasers from backreflections and to reroute the light flow. In this paper, an integrated polarization-independent device that can be operated as an optical isolator or an optical circulator, based on an InP membrane on silicon platform, is demonstrated. A cerium-doped yttrium iron garnet die is adhesively bonded on a Mach–Zehnder interferometer, in combination with four polarization converters. The device shows maximum optical isolations of 27.0 dB for transverse-electric (TE)-mode input and 34.0 dB for transverse-magnetic TM-mode input. The device also works as a four-port optical circulator. Optical isolations of at least 18.6 dB and 16.4 dB are measured between each circulator port pair for TE- and TM-mode input, respectively. This work could remove the optical interfaces between laser and isolator for robust production. It also provides a step forward toward a multifunctional and high-density PIC.

A Fourier Domain Mode Locked (FDML) laser with active mode locking has been modeled and designed. A detailed simulation study revealed that a radio frequency tuning accuracy of better then1 MHz is required to achieve FDML operation. The amplifier current and the modulation depth of the tunable intracavity filter are linked, and reveal the presence of a FDML threshold current. Initial measurements of the tunable filter performance in a realized device have been made.

A two-section semiconductor laser can exhibit excitability for certain parameter settings. When used as a photonic spiking neuron, it is relevant to investigate its sensitivity to noise due to, e.g., spontaneous emission. Under excitable conditions, the system emits irregularly timed noise-triggered pulses. Their statistics is analyzed in terms of a first-passage time distribution for the fluctuating intensity to reach the threshold for excitable response. Two analytic approximations valid for short and long times, respectively, are derived which very well explain measured and simulated pulse-repetition time distributions. This provides physical insight into the noise-triggered spiking mechanism.

This work presents a hybrid modeling technique to simulate extended cavity semiconductor mode-locked lasers, using a combination of traveling wave equations with the nonlinear Schrödinger equation. The simulations are compared to and show correspondence with experimental results from a III-V-on-silicon mode-locked laser.

We introduce a novel integrated hybrid plasmonic-photonic device for all-optical switching and reading of nanoscale ferrimagnet bits. The racetrack memory made of synthetic ferrimagnetic material with a perpendicular magnetic anisotropy is coupled on to a photonic waveguide onto the indium phosphide membrane on silicon platform. The device which is composed of a double V-shaped gold plasmonic nanoantenna coupled with a photonic crystal cavity can enable switching and reading of the magnetization state in nanoscale magnetic bits by enhancing the absorbed energy density and polar magneto-optical Kerr effect (PMOKE) locally beyond the diffraction limit. Using a three-dimensional finite-difference time-domain method, we numerically show that our device can switch and read the magnetization state in targeted bits down to ~100 nm in the presence of oppositely magnetized background regions in the racetrack with widths of 30 to 120 nm, clearly outperforming a bare photonic waveguide. Our hybrid device tackles the challenges of nonlinear absorption in the waveguide, weak PMOKE, and size mismatch between spintronics and integrated photonics. Thus, it provides missing link between the integrated photonics and nanoscale spintronics, expediting the development of ultrafast and energy efficient advanced on-chip applications.

Reconfigurable waveguide components are promising building blocks for photonic neural networks and as an optical analogue to field-programmable gate arrays. By changing the effective index of the waveguide, reconfigurable waveguide components can achieve on-chip light routing and modulation. In this paper, we design and demonstrate an Sb2S3-reconfigurable InP membrane Mach–Zehnder interferometer (MZI) on a silicon substrate. Sb2S3, which has tunable refractive index and low absorption in the near-infrared spectrum, was patterned on the InP waveguide MZIs to make an optical switch in the telecoms conventional-band. By laser induced crystallisation of the Sb2S3, it was possible to control interference in the MZI and achieve 18 dB on/off switching at 1540 nm. Laser reamorphisation and reversible switching of the Sb2S3layer resulted in damage to the waveguide structure. However, simulations show that transition metal di-chalcogenide two-dimensional crystal layers can act as efficient thermal barriers that prevent thermal damage to the waveguide during laser amorphisation. Therefore, combining Sb2S3with InP waveguides seems to be a feasible approach to achieve low-loss reprogrammable waveguide components for on-chip photonics routing and neural networks.

Butt-joint regrowth is widely used in photonic integration, but it has been challenging to break the density-quality tradeoff due to the edge growth rate enhancement (GRE) effect. In this work, we propose a scheme to circumvent this tradeoff by using large regrowth masks whose centers are exposed to epi-growth for neutralization of the excessive species. With the GRE under control, epi-stacks with arbitrarily large sizes supporting dense arrays can be butt-joint integrated with minimal compromise to their epitaxy quality. In our experiment, multi-quantum-well-based material of an exceptionally large area of 0.5 × 1.7 mm2 was epitaxially integrated with passive InP material on the same wafer. A more than 20 × reduction in edge topology compared to conventional methods was achieved.

In this paper, we propose a compact integrated hybrid plasmonic-photonic device for optical reading of nanoscale magnetic bits with perpendicular magnetic anisotropy in a magnetic racetrack on top of a photonic waveguide on the indium phosphide membrane on silicon platform. The hybrid device is constructed by coupling a doublet of V-shaped gold plasmonic nanoantennas on top of the indium phosphide waveguide. By taking advantage of the localized surface plasmons, our hybrid device can enable detection of the magnetization state in magnetic bits beyond the diffraction limit of light and enhance the polar magneto-optical Kerr effect (PMOKE). We further illustrate how combining the hybrid device with a plasmonic polarization rotator provides magneto-optical read-out by transforming the PMOKE-induced polarization change into an intensity variation of the waveguide mode. According to the simulation results based on a three-dimensional finite-difference time-domain method, the hybrid device can detect the magnetization states in targeted bits in a magnetic racetrack medium down to ~100×100 nm2, regardless of the magnetization state of the rest of the racetrack with a relative intensity contrast of greater than 0.5% for a ~200×100 nm2magnetic bit. We believe our hybrid device can be an enabling technology that can connect integrated photonics with nanoscale spintronics, paving the way toward ultrafast and energy efficient advanced on-chip applications.

This study presents the design, fabrication and experimental demonstration of a magneto-photonic device that delivers non-volatile photonic memory functionality. The aim is to overcome the energy and speed bottleneck of back-and-forth signal conversion between the electronic and optical domains when retrieving information from non-volatile memory. The device combines integrated photonic components based on the InP membrane on silicon (IMOS) platform and a non-volatile, built-in memory element (ferromagnetic thin-film multilayers) realized as a top-cladding on the photonic waveguides (a post-processing step). We present a design where the phase of the guided light is engineered via two mechanisms: the polar magneto-optical Kerr effect (MOKE) and the propagation in an asymmetrical cross-section (triangular) waveguide. Thanks to its design, the device yields different mode-specific transmissions depending on the memory state it encodes. We demonstrate the recording of the magnetic hysteresis using the transmitted optical signal, providing direct proof for all optical magnetic memory reading using an integrated photonic chip. Using mathematical model and optical simulations, we support the experimental observations and quantitatively reproduce the Kerr signal amplitudes on-chip. A 1% transmitted power contrast from devices is promising indicating that in a shot noise limited scenario the theoretical bandwidth of memory read-out exceeds 50 Gbits/s.

In this work we report the results of high density multi-channel optical multiprobes with pitches of 25 ${\mu }\rm{m}$ and 50 ${\mu }\rm{m}$ that provide edge-coupling used for on-wafer parallel testing of photonic integrated circuits. The probes are fabricated in an oxynitride platform and test demonstrations were carried out of edge-coupled indium-phosphide based photonic integrated circuits (PICs). Thirty-two optical parallel connections are simultaneously, passively aligned between the probe and the PIC by means of integrated guiding channels. The initial placement tolerance is more than 4 ${\mu }\rm{m}$ to give a passive alignment with an optical power variation of less than 1 dB. Multi-port loop-back optical power measurements are reported and the wavelength-dependent net modal gain of integrated semiconductor optical amplifiers was measured to further validate the concept.

We present a characterization method for polarization converters which improves the accuracy of traditional characterization methods significantly. An experimental demonstration of the method is presented on the InP-membrane-on-silicon (IMOS) platform. The design and fabrication of the polarization converter is discussed, as well as the simulated polarization conversion efficiency. A device of only 4 microns is shown to achieve 97.5%±0.5% polarization conversion, corresponding to an extinction ratio of -16± 0.9 dB. The traditional characterization method is compared to the new 4-port method, and the accuracy is improved from up to 20% to 0.5%.

We demonstrate the broadband operation and beam calibration over 70nm tuning range of an optical phased array (OPA) fabricated in a generic InP photonic integration platform, which enables multi-wavelength OPA operation. The broadband performance was demonstrated on an 8-channel OPA, whose calibration and phase modulator characterization were executed through near-field and far-field measurements. The architecture reported here is scalable, and the results are promising for reducing the complexity of calibration and control of large-scale OPAs for their use at multiple wavelengths, for example, for spectral imaging or 2D beam steering through dispersive gratings.

A V-band Vivaldi antenna design for beyond-5G base station applications operating within V-band is demonstrated. The device can be used for interfacing with radio-over-fibre links and optoelectronic components through a coplanar waveguide to slotline transition. Simulations show an end-fire radiation with a 3 dB gain bandwidth ranging between 46.9-77.4 GHz combined with the reflection coefficients remaining below-10dB for the same frequency range. A comb structure inspired by optical grating couplers is added providing an increased maximum gain of 12.6 dBi at 68.5 GHz. Measurement results validate the promising characteristics of the planar antenna.

An integrated two-section laser with saturable absorber and gain section fabricated in an InP technology platform is analysed. Bistability and a voltage depending self-spiking behaviour are demonstrated. Additional simulations show that the self-spiking behaviour is likely triggered by noise, and that the pulse density can be controlled by the absorber voltage. This makes the proposed device a promising encoder in the input layer of a photonic spiking neural network.

In this paper, we show how designed loss in open quantum systems can break the reciprocity of field propagation, and how non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear. In particular, we show how unidirectional propagation can be achieved for input states of certain symmetry in linear schemes, and demonstrate the possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build a non-reciprocal asymmetric field distributor with a planar structure of dissipatively coupled waveguides. We discuss the feasibility of the considered schemes and suggest possible realizations.

We report experimental and theoretical investigations with high-speed µ-OLEDs and demonstrate promising optical pulse responses as short as 400 ps using Alq3. These observations indicate that high-speed µ-OLEDs can be used for light communication in the GHz regime. The measurements are for in-house fabricated µ-OLEDs without cavity and size of 100 µm x 100 µm. With a validated model for an electrically pumped OLED, we simulate the generation of ultra-short optical pulses. The model includes Stoke-shifted reabsorption and field-enhanced Langevin recombination rate. For the Alq3 system we compare the results with the above-mentioned measurements. The good agreement between the measurement and the simulation is the basis for further study of the prospects for ultra-short dynamics and organic laser diode operation on the ps time scale.

In this work we have demonstrated a waveguide integrated uni-traveling carrier photodiode on an InP-membrane-on-silicon platform with 3 dB bandwidth beyond 110 GHz. With design optimization and an improved process, devices as small as $ \text{3}\times \text{2}\;\mu \text{m}^2$ are successfully realized. An electrical equivalent circuit model based on measured S-parameters revealed ultra-small series resistance and junction capacitance as low as 6.5 $\Omega$ and 4.4 fF, respectively, in the diodes. The model also provided insight in the photocurrent dependent characteristics in the bandwidth and resonsivity of the devices. Finally, data transmission measurements are demonstrated, showcasing the high speed telecommunication abilities of the UTC-PD.

We report experimental and theoretical investigations with an in-house fabricated tris(8‐hydroxyquinoline)‐aluminum (Alq3)-based high-speed micro-organic light-emitting diodes (μ-OLEDs) and demonstrate very promising optical pulse responses as short as 400 ps. With a model for an electrically pumped OLED, we simulate the emission of sub-nanosecond optical pulses. The model includes field-dependent (Poole-Frenkel) Langevin recombination and reabsorption of photons by singlets (Stokes-shifted), and by triplets (TA). The good agreement between the measurement and the simulation is the basis for further study of the prospects on the ps time scale, i.e. stimulated emission and conditions for laser operation. For an Alq3-based micro-OLED with high-Q optical cavity, we predict pulsed laser operation with damped relaxation oscillations in the GHz regime and several orders of magnitude linewidth narrowing, but only during 3 ns at most. The simulated current density threshold values vary from 10 kA cm−2 for Q= 500 to less than 1 kA cm−2 for Q = 1000. No continuous-wave (CW) lasing is found due to the accumulation of triplet excitons for t > 5 ns, which has two deteriorating effects, (a) suppression of the gain-providing singlet excitons due to singlet-triplet absorption and (b) suppression of the photon density due to photon absorption by triplets (TA). Prospects for CW-lasing with other organic molecules are discussed.

On-chip spectrometers with tailored spectral range and compact footprint have been pursued widely in the last decade. Splitting different frequencies typically requires a propagation length that scales inversely with the frequency resolution, which leads to a trade-off between resolution and size. Scattering media in the diffusive regime provide a long light path and multipath interference in a compact area, resulting in strong dispersive properties that can be used for on-chip compressive spectrometry. However, the performance suffers from the low light transmission through the diffusive medium. It has been found that there exist “open channels” such that light with certain wavefronts can pass through the medium with high transmission. Here we show that a scattering structure can be designed so that open channels match target input/output channels in order to maximize transmission while keeping the dispersive properties typical of diffusive media. Specifically, we use inverse design to generate a scattering structure where the open channels match the output waveguides at desired wavelengths. For a proof of concept, we propose a 1 × 10 multiplexer covering a band of 500 nm in the mid-infrared spectrum, with a footprint of only 9.4 µ m × 14.4 µ m . We also show that filters with nearly arbitrary spectral response can be designed, enabling a new degree of freedom in on-chip spectrometer design, and we investigate the ultimate resolution limits of these structures. The structures can also be designed based on a simple geometry consisting of circular holes with diameters from 200 to 700 nm etched in a dielectric slab, making them highly suited for fabrication. With the help of compressive sensing, the proposed method represents an important tool in the quest towards integrated lab-on-a-chip spectroscopy.

Integrated optical true time delay lines attract lots of attention for optically controlled mm-wave beam steering due to its low-loss/broadband performance and stable/compact system architecture. However, for remotely-controlled networks, the techniques that require local-site actively-tuned elements would make the network control more complicated. A passive design using wavelength-tuning is regarded as a promising candidate. In this paper, an integrated wavelength-tuned optical mm-wave beamformer with doubled delay resolution is proposed and demonstrated in a generic InP platform. A bidirectional looped-back arrayed waveguide grating (AWG) module acts as the stepwise tunable delay unit. By introducing an extra AWG router for delay mode (positive/negative) selection and a bidirectional optical interface, a pure λ-tuned, resolution-doubled optical delay network is realized without using any active component (e.g. heaters, current injection) at the local site. This photonic passive design is more beneficial to the remotely-controlled mm-wave beam steering system. Furthermore, the AWG router potentially allows multi-port wavelength switching to support the scaling-up of the network. The fabrication-caused delay error of

We report on the free-running and frequency stabilized operation of a ring resonator-tuned full-band tuneable laser. The laser is a monolithically integrated semiconductor ring laser tuneable over 34 nm, from 1522-1556 nm, fabricated using a commercially-available, InP-based, active-passive foundry technology. The mode selection is implemented using the Vernier effect by reverse-biasing voltage-controlled electro-optically tuned ring resonators. The laser exhibits a typical intrinsic linewidth of 110 kHz over the C-band and a side-mode suppression ratio (SMSR) exceeding 50 dB. The linewidth over the tuning range does not significantly vary, showing that the tuning mechanism does not cause linewidth broadening. The power dissipated in the tuning elements is 1.4 mW per ring. Using the same reverse bias voltage-controlled electro-optic tuning, we also demonstrate the locking of the laser to a high-finesse etalon using Poun-Drever-Hall frequency locking. Our implementation requires a single control loop because of the reverse bias tuning. All deployed tuning effects in the phase modulators have the same sign therefore resulting in a flatter frequency dependent phase response compared to current injection feedback. The control loop has a bandwidth of 500 kHz and a control range of 2.9 GHz. We report 1 kHz level linewidth for millisecond observation times for the stabilized laser.

In this study, we provide extensive analysis of the (unique) characteristics of phishing and spear-phishing attacks, argue that spear-phishing attacks cannot be well captured by current countermeasures, identify ways forward, and analyze an advanced spear-phishing campaign targeting white-collar workers in 32 countries.

The literature reports some experiments on light communication based on organic light emitting diode emitters with data rate up to 1.13GBit/s [1]. We present theoretical and experimental evidences indicating that high-speed OLEDs exhibit dynamical behavior in the sub-nanosecond time scale which opens perspectives for Light Communication not only in the GHz regime but tenfold larger. From the theoretical point of view, we will present an electrical dynamical model and an organic laser diode dynamical model based on rate equations that predict both spontaneous and stimulated emission dynamical behaviors in the sub-ns and picoseconds time scale following electrical pulsed excitation. These models also describe emission of Organic light emitting diodes (OLED). Simulations show that firstly, spontaneous emission with 800ps optical pulses and below are possible. Secondly, above threshold, dynamical optical responses of Alq3 based organic devices predict relaxation oscillations with frequencies from 4GHz to 14GHz [2]. In the experimental section we present both the fabrication aspect of the devices and the measured electrical and optical responses of high-speed OLEDs. Among the fabrication aspect, we describe the design and the fabrication of coplanar waveguide necessary to provide 50 Ohm characteristic impedance to the high-speed OLED electrodes [3]. We also present the fabrication of distributed feedback (DFB) nanostructures compatible with organic heterostructures as necessary cavity for the development of organic laser diodes. Different types of measurement are presented; firstly we report optical pulses of 1ns, 800ps and down to 400ps in duration emitted by specifically designed High-Speed OLEDs. We present also optical and electrical measurement of 100x100μm2 OLED to 20ns electrical pulses at medium (460A/cm2) and high (8.8kA/cm2) current density [4]. These measurements are fitted with simulations, thus validating the proposed dynamical model and giving credibility that OLED can be as fast as, or even faster than III-V based LEDs. Finally, the combined conclusions from the models and the measurements are twofold. Firstly the fabrication and the demonstration of organic laser diode is at hand with cavities and current density large enough to reach the laser threshold. Secondly, we propose High-Speed-OLED based organic light-communication emitters: together with Direct-Current Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) and bit/power loading algorithms allowing spectral efficiency as high as 8bit/Hz/s, we project data transmission rates up to 10Gbit/s.

A butt-joint SOA design for InP on Si membrane (IMOS) platform is proposed. The new design features the butt-joint interface between the SOA and passive nanophotonic waveguide, which makes the interface a factor of 2 to 6 shorter than in the current twin-guide SOAs, with possibility to reduce it further to factor of 5-10. This makes the new SOA a promising candidate for high-speed directly modulated lasers (DML) applications, where extremely short SOAs (40-100 μm long) and short distances between reflectors are usually required.

We present an optical phased array (OPA) photonic integrated circuit based on an InP generic platform with on-chip amplification. To the best of our knowledge, it is the OPA with the highest on-chip optical gain reported in literature. The proof-of-principle OPA chip has 8 channels and includes a booster semiconductor optical amplifier (SOA), and in-line SOAs for amplification in all arms. We investigated the optical amplification performance at different current injection levels in an 80nm wavelength range. We measured a maximum on-chip optical gain of 8.6dB at 1530nm for an on-chip input laser power of 5dBm, delivering a total output power of 23mW. The results are promising for OPA-based LiDAR systems where output power is critical to increase the sensing range.

An InP integrated widely tunable laser is investigated for the use as a swept source in optical coherence tomography (OCT) applications. The laser is realized on a generic integration technology platform. It consists of a gain medium and a bandpass filter with 3 cascaded asymmetric Mach-Zehnder interferometers. The additional presence of a balanced Mach-Zehnder modulator as variable out-coupler is instrumental to increase the laser tuning range to 90 nm between 1480 and 1570 nm but can add to additional filtering effects in the laser cavity. In this work, we propose an optimized control strategy for the wavelength calibration of this widely tunable laser source, for a stepwise wavelength scan that is suitable for OCT. The aim is to obtain a wavelength scan with at least 1000 of 10 GHz equally spaced optical frequencies, having uniform power around 100 µW and 1 GHz accuracy. The control strategy is based on the a-priori knowledge of the coarse and the medium filter tuning and on an optimization of the fine filter tuning and the longitudinal cavity mode tuning that can be frequently updated. In this way, the calibration of the laser system can be kept sufficiently accurate and stability of the scan quality can be ensured. With this strategy, 10 GHz spaced optical lasing frequencies are obtained over 30 nm making the calibrated laser suitable as an OCT source.

We experimentally investigate sensitivity to external optical feedback in a modified semiconductor ring laser with filtered optical feedback. Feedback insensitive, single-mode lasing with SMSR below -40dB over a 76mA range is demonstrated.

Photonic membrane platforms attract a lot of research attention, because they can potentially enable integration of photonic and electronic components on a single chip. In membrane platforms photonic devices are usually separated from the substrate by a thick layer of insulator, so they suffer from inefficient heat sinking. We propose to bond membrane lasers on BCB and tune the bonding layer thickness to reduce the gap between the p-contact of the laser and the substrate, while an extra BCB layer is spun on the Si substrate to improve adhesion and reduce mechanical stress. This method enables direct heat sink from the membrane to the Si substrate on 3-inch wafer scale.

RC and transit time limited bandwidth of balanced detector is investigated through an equivalent circuit model. While series resistance is not a critical parameter, junction capacitance and load impedance play major roles in resulting bandwidth.

We present the frequency stabilization of a monolithically integrated extended cavity single mode InP diode laser using the Pound-Drever-Hall (PDH) frequency locking technique. The laser is a multi-section distributed Bragg reflector (DBR) laser with an intra-cavity ring resonator, fabricated using an InP active-passive integration technology. The laser is locked to a 700 kHz wide resonance of a Fabry-Perot etalon. The single electrical feedback is applied on the reverse biased rear DBR section of the laser, used to tune the lasing mode. This is the first time to our knowledge that the feedback is applied on a reverse biased, voltage controlled section of an integrated laser cavity. In our implementation the tuning is based on electro-optic effects avoiding significant thermal effects in the tuning element. We demonstrate a linewidthreduction down to 5 kHz and frequency noise suppression of about 30 dB at 10 Hz offset frequency. The bandwidth of the control loop is about 500 kHz, limited by the phase delay of components in our loop.

We present waveguide photonic crystal reflectors on the InP-membrane-on-silicon (IMOS) platform, and a method to accurately measure the reflectivity of those reflectors. The photonic crystal holes are patterned on a waveguide using electron-beam lithography and etched through the waveguiding layer to create a broadband distributed Bragg reflector. We show simulations of these reflectors and experimental results of fabricated devices, both showing a high, free-to-choose reflectivity, and high quality factor Fabry-Pérot cavities. We experimentally show reflectivities higher than 95% for the reflectors and a quality factor as high as 15,911±511 for a Fabry-Pérot cavity, using reflectors with a length of only 4 microns. For the first time, to our knowledge, two methods for measuring the reflectivity are used for characterization of on-chip reflectors to accurately determine the reflection. The first method is based on analysis of the transmission through a Fabry-Pérot cavity, the second is based on a direct four-port measurement of the reflector. A systematic error is made in both methods, resulting in an upper and lower boundary for the actual reflection coefficient.

A voltage-driven InP/InGaAsP 1 × 2 optical switch based on multimode interference (MMI) is proposed and numerically studied. In plane shift of the optical field across the output cross-section of a multimode waveguide enables optical switching between two symmetric output waveguides. Two twin electrodes on top of the multimode waveguide are tuned with reverse bias voltage to switch output port by reconfiguration of the refractive index profile. The optical switching mechanism and the design method are explained through a modal analysis of the wide perturbed waveguide. An optical switch design with an input waveguide width of 20 µm, output waveguide widths of 8 µm, and electrode length of 1.3 mm is proposed. The numerical prediction of the device performance is provided by combining a calibrated model of the voltage-perturbed refractive index and absorption with electrical and optical solvers. Simulation results show that an extinction ratio of 29 dB can be achieved at an optical wavelength of 1550 nm and with a switching voltage of −12 V.

We have theoretically analyzed multi-stability of a symmetric ring laser operating in one single longitudinal mode in the presence of coherent back scattering and inversion-grating-induced mutual coupling of the clockwise and counter-clockwise modes. Our model takes into account the inversion grating created by the standing-wave pattern of the interfering counter-propagating fields and avoids the frequently used ad-hoc introduction of cross and self-saturation coefficients. Our study confirms that linear coupling due to waveguide irregularities or weak interface reflections leads to an effective pump strength below which the clock and anti-clock wise modes are symmetrically coupled whereas above which the grating-induced coupling leads to multi-stability.

Probabilistic shaping based on constant composition distribution matching (CCDM) has received considerable attention as a way to increase the capacity of fiber optical communication systems. CCDM suffers from significant rate loss at short blocklengths and requires long blocklengths to achieve high shaping gain, which makes its implementation very challenging. In this paper, we propose to use enumerative sphere shaping (ESS) and investigate its performance for the nonlinear fiber optical channel. ESS has lower rate loss than CCDM at the same shaping rate, which makes it a suitable candidate to be implemented in real-time high-speed optical systems. In this paper, we first show that finite blocklength ESS and CCDM exhibit higher effective signal-to-noise ratio than their infinite blocklength counterparts. These results show that for the nonlinear fiber optical channel, large blocklengths should be avoided. We then show that for a 400 Gb/s dual-polarization 64-QAM WDM transmission system, ESS with short blocklengths outperforms both uniform signaling and CCDM. Gains in terms of both bit-metric decoding rate and bit-error rate are presented. ESS with a blocklength of 200 is shown to provide an extension reach of about 200 km in comparison with CCDM with the same blocklength. The obtained reach increase of ESS with a blocklength of 200 over uniform signaling is approximately 450 km (approximately 19%), 9 pages, 12 figures