This PDF file contains the front matter associated with SPIE Proceedings Volume 11705, including the Title Page, Copyright information and Table of Contents

Next generation short and long reach communication networks would be required to provide data rates of multiterabit/ s. Such high line rates are not feasible using a single wavelength channel. However, the multi-terabit/s transmission capacity can be achieved by utilising highly parallel wavelength division multiplexing (WDM), with tens or hundreds of channels, in combination with spectrally efficient advanced modulation formats. Quantum dot (QD) coherent comb lasers (CCLs) are promising light sources for Terabit/s dense-WDM optical coherent and data center networks because such monolithic QD-CCLs solve the obvious cost, power consumption and packaging problems by replacing many separate lasers for each channel by only a single semiconductor laser. Other advantages include compact size, simple fabrication, and the ability for hybrid integration with silicon substrates. Recent years we have successfully developed InAs/InP QD CCLs with repetition rates from 10 GHz to 1000 GHz and a total output power up to 50 mW per facet at room temperature. In this paper we have presented the design, growth, fabrication, electronic control and packaging of the QD CCLs. The key technical specifications include L-I-V curves, optical and RF beating spectra, relative intensity noise and optical phase noise of each individual wavelength channel, as well as timing jitter are investigated. Data bandwidth transmission capacity of 5.376 Terabit/s and 10.8 Terabit/s in the PAM-4 and 16-QAM modulation formats are demonstrated by using a single QD CCL chip with a channel spacing of 34.2 GHz after 25 km and 100 km of single-mode fiber transmission lines, respectively.

An amplitude-modulated optical frequency comb generated by a passively mode-locked InGaAs double quantum well semiconductor laser is optically injected into a laser emitting a single optical mode continuous wave output in solitary operation. Optical frequency comb generation in the injected laser is experimentally demonstrated and regimes of injection locking are analyzed.

The transition from frequency-modulated to amplitude-modulated frequency comb operation is studied experimentally in a multi-section InAs/InGaAs quantum dot frequency comb laser. Temporally and spectrally-resolved intensity and phase as well as time and frequency domain analysis allow to identify frequency-modulated and amplitude-modulated comb operation regimes in dependence on the laser gain current and absorber reverse bias voltage.

We demonstrate the first on-chip laser frequency comb based on hybrid integration with low-loss Si3N4 waveguide circuits. The laser comprises an InP diode amplifier of which a small fraction is reverse biased for passive locking, while a Si3N4 feedback waveguide extends the optical cavity to a roundtrip length of 15 cm. The generated comb densely covers a 25 nm broad spectrum, at a 3 dB level, with more than 1600 comb-lines at 2 GHz spacing. With such properties, hybrid integrated diode lasers show great promise for widespread use in applications such as integrated microwave photonics or metrology.

In this work, we compare ultrashort pulse generation in a monolithic two-section diode laser chip based on passive- and self- mode-locking (PML and SML) regimes at 1550 nm. In PML, we apply a forward current into the gain segment and a reverse voltage into the absorber segment. For SML operation, both segments are operated by applying a forward current. Strongly chirped pulses with an autocorrelation-width of roughly 7-8 picoseconds are obtained for both cases. We analyze the potential for fiber-based compression of the pulse widths down to the sub-picosecond range.

Optical self-injection stabilization of a passively mode-locked InGaAs double quantum well semiconductor laser is reported. Time-domain, frequency-domain and spectral domain measurement results in dependence on feedback strength and feedback delay demonstrate pulse width and higher harmonic mode-locking control. Traveling-wave equation simulations allow to explain the measured sequence of harmonic mode-locking orders in dependence on the feedback strength and delay.

Topology plays a fundamental role in contemporary physics and enables new information processing schemes and wave device physics with built-in robustness. However, the creation of photonic topological phases usually requires complex geometries that limit the prospect for miniaturization and integration, and, dispossess designers of additional degrees of freedom needed to control topological modes on-chip. By controlling the degree of asymmetry (DoA) in a photonic crystal with broken inversion symmetry, we report single-mode lasing of valley-Hall ring cavities at telecommunication wavelength. Our results open the door to novel optoelectronic devices and systems based on compact topological integrated circuits.

InAlGaN-based laser diodes (LDs) can be designed to emit across a wide range of wavelengths spanning UV to green. A common challenge across all wavelengths lies in the difficulty in producing low resistance p-type InAlGaN layers. For shorter wavelength devices, the requirement of high aluminium containing p-AlGaN leads to high device series resistance. For the longer wavelength devices approaching the green wavelengths, the thermal degradation of the indium-rich quantum wells during the growth of the p-GaN and p-AlGaN cladding layers reduces the device efficiency. In this paper we discuss how BluGlass’s remote plasma chemical vapour deposition (RPCVD) technology can address these challenges through improvements to intrinsic material properties as well as enabling novel design architectures.

We analyze changes in carrier recombination in the quantum well (QW) active region of UVB light emitting diodes. For this purpose, we established an experimental approach for in-situ characterization of aging processes by direct comparison of QW luminescence generated by two different pump mechanisms, continuous current injection and shortpulse optical excitation. This allows the quantification of changes in recombination kinetics during device operation. We observe a reduction of the luminescence decay time from ~250 to ~200 ps within the first 42 hours of high current density stress. Moreover, trap-like defect centers are generated or activated, which capture non-equilibrium carriers ultrafast and reduce the luminescence power.

The material gain and threshold current density properties of dilute-As InGaNAs-based quantum wells (QWs) are analyzed via a self-consistent 6-band k·p formulism. Amber emission is achieved by the implementation of dilute-As InGaNAs with low In-content. Significant threshold current density reduction and enhanced material gain are obtained by the employment of an In0.19Ga0.81N0.97As0.03 (Eg ~ 2.1 eV) alloy into the active region for red-emitting lasers, compared to a conventional high In-content InGaN-based QW emitting at the same wavelength (λ~600 nm). Our study reveals the excellent potential of the dilute-As InGaNAs for implementation as the active region for red-emitting lasers.

Type-II GaInAs/GaAsSb “W” quantum well heterostructures on GaAs show strong potential for temperature-stable data communications lasers. Devices emitting at 1255 nm show promising lasing characteristics including room-temperature threshold current densities, Jth < 300 A/cm^2, pulsed output powers >1 W, and a reduced wavelength temperature dependence of 0.31 nm/C. Temperature- and pressure-dependent characterisation techniques are used to determine the roles of radiative and non-radiative recombination. Analysis of these characteristics suggest a reduced influence of non-radiative recombination on the thermal stability of type-II “W”-lasers compared to type-I devices, as will be discussed along with recommendations for future device development.

Direct band gap achievements in germanium by alloying with tin or by tensile strain engineering has enabled, in recent years, several demonstrations of laser emission in the 2-5µm wavelength range. This fast and promising emergence of CMOS-compatible laser technology in the Mid-IR faces, however, major issues, e.g. high threshold power densities, which limit the integration of GeSn as a gain media on a silicon chip for cost-efficient sensing and/or short-range Datacom devices. We show that combining tensile strain and Sn alloying enables one to effectively engineer the material band structure and its optical gain properties. We also evidence the importance of defects management on GeSn lasing characteristics, beyond the band-structure engineering. We discuss the potential of GeSnOI technology to address the above-mentionned aspects, which enabled to drastically reduce the lasing thresholds in microdisk laser cavities and reach continuous-wave operation in GeSn.

Micro-transfer-printing (µTP) enables the intimate integration of diverse non-inherent functionalities on a target substrate and hence allows for the realization of complex photonic integrated circuits (PICs) with small footprint. By employing a polydimethylsiloxane (PDMS) elastomeric stamp with an array of posts, a large number of micro-components can be integrated on a target wafer in one transfer printing operation, which leads to substantial cost reduction of the resulting PICs. This paper discusses the use of µTP for the realization of III-V lasers on Si and SiN PICs and summarizes the recent progress that has been made in this field.

This paper reports on the impact of the quality of the epitaxial structure of InAs Quantum Dot (QD) lasers grown on silicon substrates on lifetime. To this aim, a series of current step-stress and constant-current aging experiments were carried out on two sets of Fabry-Pérot QD lasers, emitting at 1.3 μm and featuring two different Threading Dislocations Densities (TDDs) within the epilayers, nominally 6E7 cm^-2 (high TDD) grown on Si substrates and 500 cm^-2 (low TDD) grown on lattice matched GaAs substrates. The results of the step-stress procedure indicate that i) the high-current optical performance of the lasers is limited by TDD, which reduces the bias range for useful Ground State (GS)-only operation and lowers the roll-off point of the optical output characteristic; ii) TDD contributes to the acceleration of the dominant optical degradation mechanism at high stress current levels, represented for this family of devices by the recombinationenhanced generation of defects in device regions close to the active layers; iii) dislocation density also accelerates optical degradation in GS regime. This process is primarily driven by the diffusion of Non-Radiative Recombination Centers (NRRCs) toward the active region of the devices, as demonstrated by the dependence of threshold current variation on the square root of time. These experimental results show that the presence of TDDs is the main limiting factor for the reliability of QD lasers for epitaxially-integrated silicon photonics applications, further confirming the outcome of previous statistical lifetime analyses carried out on devices featuring similar epitaxial structures.

We report temperature dependent optical modal gain and absorption features as function of injection current of 1.55 μm InAs Q-Dash laser with an InAs/InAlGaAs/InP structure monolithically grown on (001) silicon substrate. Board-area multi-segmented contact devices were fabricated and driven by pulsed current. Net modal gain and absorption was obtained by measuring amplified spontaneous emission using the variable stripe-length method. From 20˚C to 80˚C, the changes in maximum gain and gain bandwidth were studied and a redshift in peak gain wavelength was observed. Quantum confined Stark effect was measured under reversed bias from -1 V to -7 V.

We present progress in high power GaAs-based single-pass semiconductor tapered optical amplifiers and modules tailored for coherent beam combining (CBC) in master-oscillator power-amplifier configuration. Amplifier design is first studied, by varying device geometry and epitaxial structure in 976nm devices. Epitaxial structures with large vertical near field and low wave-guiding from the active region enable higher CBC efficiency. However, changes to in-plane geometry did not improve performance. Overall, CBC of tapered amplifiers is stable, reproducible and robust, motivating next the development of 1064nm CBC-ready stand-alone sub-modules. Design, construction and test results from the pilot-series fabrication of these amplifier modules are presented.

We present 940nm GaAs-based high-power broad-area diode lasers that use an enhanced self-aligned lateral structure "eSAS", implemented within an extreme-triple-asymmetric vertical structure with a thin p-side. In this structure, two-step epitaxial growth with intermediate selective etching is used to introduce current-blocking structures consisting of n-doped GaAs and InGaP layers outside the laser stripe, whose location, thicknesses and doping concentrations are precisely defined. These blocking structures confine current to the device center, thus reducing carrier losses in the edges and limiting the detrimental effects of lateral current spreading and carrier accumulation on beam quality, without compromising conversion efficiency, output power or polarization purity. We present results of eSAS single-emitters as well as bars with multiple emitters, in comparison to gain-guided reference devices. In addition, we demonstrate optimized blocking structures with improved current blocking, which are crucial for the realization of the eSAS structure.

Lasers in the spectral range around 785 nm are requested as pump lasers for 2 μm eye-safe Tm:YAG lasers and as excitation light sources in Raman spectroscopic experiments with large excitation areas. The output power should be in the range of several watts together with wavelength stabilization and good beam quality. Distributed Bragg Reflector (DBR) tapered diode lasers offer a potential solution. In this contribution 785 nm DBR tapered lasers with a narrow spectral emission width below 1 pm will be presented. The devices are based on GaAsP single quantum wells embedded in a 1 μm thick large optical cavity leading to a vertical far field angle of 29° (FWHM). The 3-inch wafers were grown using metalorganic vapor phase epitaxy. In a full wafer process 4 mm long DBR tapered lasers were manufactured. Two different layouts were processed. One device type (A) consists of a 1.0 mm long 10th order surface DBR grating acting as rear side mirror, a 1.0 mm long ridge waveguide section, and a 2.0 mm long flared section having a full taper angle of 6°, whereas the other one (B) has a 500 μm long DBR grating, a 1.0 mm long RW section and a 2.5 mm long 6° flared section. Both types of devices reach output powers larger than 5 W at 25°C. The device with the shorter tapered section (A) is limited to this output power, whereas the device with longer taper (B) reach up to 7 W within the studied current range up to 8 A. At 3 W output power the latter device has an emission linewidth below 1 pm. Measured at 1/e2 level at this output power the beam waist width of 8.5 μm and the far field angle of 14.4° lead to a beam propagation ratio M2 of 2.1. More than 71% of the emitted power is within the central lobe of the beam waist.

A GaAs/AlGaAs distributed feedback semiconductor (DFB) laser with a laterally-coupled grating is demonstrated at a wavelength of 780.24 nm with an output power up to 60 mW. A mode expander and aluminum-free active layers have been used in the material epilayer to reduce the linewidth to 612 kHz while maintaining high output power. The fabricated laser demonstrates over 40 dB side-mode suppression ratio with tuning range > 0.3 nm, which is suitable for atom cooling experiments with the D2 87Rb atomic transition and provides substantial potential for the laser to be integrated into miniaturized cold atom systems.

Quantum cascade laser optical frequency combs are opening new possibilities in mid-infrared spectroscopy. Using a dual comb spectroscopy, spectrum acquisition at 8um were achieved with a very short time resolution (10us) and very high accuracy (1m Absorbance); using interleaving techniques high resolution (~3MHz) measurements over a full bandwidth of 55cm-1 with an acquisition time of only 120ms were achieved. In this context, we discuss improvement of the QCL comb stability using ring QCLs geometries, RF injection in specially designed devices. Furthermore, we perform the comparison between the coherent intermode beat spectroscopy and upconversion of the output intensity as characterization tools for the comb.

It is a well-established truth that spatial hole burning (SHB) in a standing-wave cavity is an essential single-mode instability mechanism for multimode operation of quantum cascade lasers (QCLs). We discovered recently that another instability mechanism–phase turbulence–is capable of triggering an onset of previously unseen types of frequency combs in traveling-wave ring cavity QCLs in absence of SHB. This new regime of laser operation reveals a connection with Kerr combs and paves the way to manipulation and engineering of comb states in QCLs.

Frequency combs are ideal candidates to realize miniaturized spectrometers without moving parts and hence are of great interest for integrated photonics. Here, an overview on the generation electrically pumped optical frequency combs on integrated platforms using semiconductor lasers. This includes self-starting generation of frequency modulated combs in quantum cascade laser in the 8um and interband cascade lasers in the 3-4um wavelength region, respectively. Furthermore, we will discuss how to integrate efficient high-speed modulators in these devices in order to facilitate the generation of picosecond pulses.

THz quantum cascade lasers (QCL) frequency combs are recently attracting attention both as valuable sources for THz spectroscopy as well as a model system to study non linear generation and laser dynamics. Harmonic comb state has proven to be emerging in quantum cascade lasers and promoted by an interplay between parametric gain and spatial hole burning. We report here on robust, self-starting harmonic mode locking in double-metal THz quantum cascade lasers. Different harmonic orders can be excited in the same laser cavity depending on the pumping conditions. The harmonic state can be RF injected and frequency pulled. We study the dependence of harmonic state on the laser cavity and we also report results on harmonic state in external cavities under RF injection.

The use of fundamental modelocking to generate short terahertz (THz) pulses and THz frequency combs from semiconductor lasers has become a routine affair, using quantum cascade lasers (QCLs) as a gain medium. Here, using time-resolved THz techniques, we show the first of demonstration harmonic injection and mode- locking in which THz QCLs are modulated at the harmonics of the round-trip frequency. This generates multiple THz pulses per round trip in both active and self-starting harmonic regimes. This behavior is supported by time-resolved Maxwell-Bloch simulations of induced gain and loss in the system. This work exploits the inherent ultrafast dynamics of QCLs and opens up new avenues in THz pulse generation.

The fast modulation of lasers is a fundamental requirement for applications in optical communications, high-resolution spectroscopy and metrology. Here, we report a new mechanism to modulate the emission from a terahertz frequency quantum cascade laser (QCL) device , whereby optically-generated acoustic phonon pulses are used to perturb the QCL bandstructure, enabling fast amplitude modulation that can be controlled using the QCL drive current or strain pulse amplitude. We show that this modulation can be explained using a perturbation theory analysis.

We devise a THz polaritonic saturable absorber exploiting ultra-strong coupled intersubband cavity polaritons generated in a multi quantum well (MQW) heterostructure. By coupling the polaritonic saturable absorber reflector with a high bandwidth heterogeneous THz QCL frequency comb (2.3-3.8 THz) we demonstrate spectral reshaping of the QCL emission and a major increase of the comb operational dynamic range up to 38% characterized by a stable single and narrow intermode beatnote.

The theory of interface roughness scattering is well established in the case of idealized abrupt interfaces. Here we generalize this theory for finite interfacial widths. Experimental findings for Ge/GeSi interfaces show that the interface roughness can be correlated along the growth directions at length scales smaller than the interfacial width. This feature is included in a generalized theory of interface roughness scattering, accounting for correlations along both in-plane and out-of-plane directions. This model is included in a nonequilibrium Green’s functions simulator, allowing to assess the impact of interface roughness on the performances of quantum cascade lasers.

We propose a generalization of the well-known Lugiato-Lefever Equation to unify the description of combs- and structures- forming nonlinear optical systems. This approach rigorously connects for the first time passive systems such as Kerr micro-resonators and active systems such as Quantum Cascade Lasers (QCLs) which were so far treated separately. The model effectively describes a unidirectional ring QCL driven by a coherent signal where we show the existence of temporal solitons and Turing rolls, previously identified only in Kerr micro-resonators, considerably increasing the theoretical insight and the technological potential of chip-scale comb sources.

New experiments with THz QCLs reveal the harmonic frequency comb regime, in which isolated modes are separated by several free spectral ranges and the optical spectrum does not have a reflection symmetry. Here we study the mechanism of the harmonic frequency combs. Our calculations show that the harmonic comb is favored if the QCL contains two lower laser states, with different but comparable strength of the optical transitions. The asymmetry between the two optical transitions can be linked to a linewidth enhancement factor. Our work can be extended to mid-IR QCLs with an asymmetric gain spectrum.

In certain lasers, frequency combs can form whose output is frequency-modulated (FM) linearly in time. While this result has been replicated numerically, the core physics have remained elusive. By deriving a mean-field theory for lasers analogous to the Lugiato-Lefever equation, we efficiently describe the dynamics of light in nonlinear laser cavities. This equation can be solved analytically with some weak assumptions, simplifying to the nonlinear Schrodinger equation with a phase potential. The phase of its solution is piecewise quadratic in time|an FM comb. Our results apply to nearly any laser and explain the diverse experimental observations.

A phenomenological linewidth enhancement factor (LEF) was recently used to explain a variety of laser dynamics, from free-running optical frequency combs (OFCs) to solitonic-structures in quantum cascade lasers (QCLs). In this work, we provide a physical origin of the LEF for the first time. The inclusion of scattering assisted optical transitions leads to considerable asymmetry of the gain lineshape, which induces a finite LEF. A k-space resolved density matrix model that incorporates multiple elastic and inelastic scattering mechanisms was used. A laser master equation including LEF is derived that shows OFC formation and provides a link to Kerr microresonators.

The integration of mid-IR lasers with Si-based platforms is needed for the development of smart sensor grids. Here we review our recent results on laser diodes (LDs), interband-cascade lasers (ICLs) and quantum-cascade lasers (QCLs), all grown on on-axis (001) Si substrates and covering emission wavelengths from 2 to 10 µm. In addition, we will demonstrate that etching facets is a viable route toward cavity definition either on plain wafers or recessed Si wafers.

We report new developments of quantum cascade lasers (QCL), made of InAs/AlSb, operating in the long wavelength mid-infrared range from 10 to 20 µm. Fabry-Pérot lasers operated in the CW regime up to a wavelength of 18 µm at 40°C, and up to 21 µm on Peltier cooler, with threshold current densities below 1 kA/cm². Distributed feedback QCL are also fabricated using a metal grating on the top of the laser ridges. They demonstrated single frequency operation in CW regime at room temperature. These lasers are suitable for new high resolution spectroscopy applications in this almost unexplored spectral range.

Step-taper active-region (STA) quantum cascade lasers (QCLs) allow for both carrier-leakage suppression and fast, miniband-like lower-laser (ll) level depopulation. That has led to an internal-efficiency value of ~ 77 % for ~ 5 μmemitting devices, a record-high value for 4.5-6.0 μm-emitting QCLs. We have recently shown that that value can be basically accounted for when considering both LO-phonon- and interface-roughness (IFR)-triggered carrier leakage from the upper-laser (ul) level and injector states. The same carrier-leakage analysis is applied to MOCVD-grown ~ 8.0 μmemitting, STA-type QCLs, and we find that the internal efficiency reaches a high value of ~ 73.6 %, due to a record-high injection-efficiency value (86.7 %) and to an IFR-enhanced laser-transition efficiency value of ~ 85 %. In contrast, for a conventional MOCVD-grown, ~ 8.0 μm-emitting QCLs the internal efficiency is found to be only ~ 55 %, typical of values extracted from experimental data of mid-infrared-emitting conventional QCLs. The ul-level lifetime is found to be controlled by LO-phonon and alloy-disorder (AD) scattering for typical MOCVD-grown QCLs, just like for 4.5-5.0 μm-emitting QCLs. However, for typical MBE-grown QCLs the ul-level lifetime is controlled by LO-phonon, AD and IFR scattering. The ll-level lifetime is found to controlled by both LO-phonon and IFR scattering. Besides the high internal-efficiency value, the use of excited-state injection and a low voltage defect result in the STA QCL reaching a single-facet wall-plug efficiency value of 10.6 %, a record-high single-facet value for 8-11 μm-emitting QCLs grown by MOCVD and holding potential for CW operation.

Scaling the coherent power of mid-infrared (IR)-emitting quantum cascade lasers (QCLs) to the multi-watt range remains an important objective for applications where the laser beam needs to travel through air to remote targets, such as freespace communication links. For such applications requiring long-range pointing accuracy, measurements of beam stability are also important. We present beam-quality measurement results of narrow-ridge (4-5 μm), 4.6 μm-emitting buriedheterostructure (BH) QCLs. A 40-stage, step-tapered active-region (STA) structure was grown by MOCVD, and ICP etching was used to make deep ridges. InP:Fe was preferentially regrown in the field regions by using an SiO2 mask for ridge etching and Hydride Vapor Phase Epitaxy (HVPE). The HVPE process is attractive for selective regrowth, since high growth rates (0.2-0.3 μm/min) can be utilized, and highly planar top surfaces can readily be obtained. HVPE regrowth has been previously employed for BH devices of MBE-grown QCL ridges, but beam-stability measurements were not reported. HR-coated, 7.5 mm-long devices were measured under QCW operation (100 μsec pulse width, 0.5%-10% duty cycle) – very good beam quality factors, M² < 1.2, were observed for both 4 μm and 5 μm ridge widths, but the narrower ridge exhibited better pointing stability. Collimated 5 μm-wide BH devices displayed some small degree of centroid motion with increasing power (< 0.125 mrad). This corresponds to a targeting error of ~1.25 cm over a distance of 100 m. Significantly improved lateral-beam stability was observed for narrower ridge width, although at the expense of reduced output power.

We have demonstrated that both ring quantum cascade (QCLs) and interband cascade lasers (ICLs) are excellent platforms for vertical light emission. Of these two lasers ICLs typically show lower power consumption and lasing threshold, qualifying them especially for miniaturized and battery-powered applications. With our work on ring ICLs we are aiming to build a compact portable sensing device, employing interferometric cavity-assisted photothermal spectroscopy. Here, we present our current work on interband cascade devices, as well as an overview of previous studies on ring QCLs. These devices rely on the light outcoupling via a second-order distributed-feedback grating from a ring cavity.

Mid-infrared semiconductor lasers have emerged as indispensable compact coherent sources for military and commercial applications. While much of the historical emphasis has been on maximizing the output power and/or spectral purity, a recent new focus has been on engineering these lasers to operate as optical frequency combs (OFCs) for broadband real-time spectroscopy. In particular, the combination of low-drive-power and broad gain bandwidth has made interband cascade laser (ICL) OFCs an attractive complement to quantum cascade laser OFCs operating at longer wavelengths. Moreover, ICL combs can potentially be incorporated into fully-integrated dual-comb spectrometers that employ fast, room-temperature IC photodetectors processed on the same chip. However, the high refractive index of the ICL’s GaSb substrate poses some challenges to the optical waveguiding. Because the modal index is considerably lower than that of the substrate, the optical field can penetrate the bottom cladding layer and leak into the GaSb, inducing wavelength-dependent interference that modifies the gain and group velocity dispersion (GVD) profiles. Even when the effect on lasing threshold is small, the comb properties can be adversely affected. Using the sub-threshold Fourier transform technique, we studied ICL combs with various ridge widths, substrate thicknesses, and center wavelengths. This allowed us to evaluate the effects of modal leakage on the GVD. We find that the resonant nature of the substrate modes induces oscillations, which affect both the spectral bandwidth and the phase-locking properties above threshold. Strategies to mitigate the GVD’s undesired and unpredictable spectral variation will be presented.

We present the design, fabrication and the characterisation of compact and widely tuneable MIR source. This device is based on an INP micro-lenses array and on a DFB QCL array. Both of those arrays are designed together to induce a beam combination. This work presents one complete device for wavelength between 8.5 and 9.5 µm with a typical size of 5*2 mm² designed for one specific solid spectroscopic application.

A photonic MOSFET includes a semiconductor laser in the drain region, and a photon sensor or avalanche photo diode (APD) in the channel / well region. The MOSFET, laser, and photon sensor are fabricated as one integral transistor. When a voltage is applied to the MOSFET gate, and a voltage is applied to the laser, both MOSFET and laser are switched to on. Light emitted from the laser is absorbed by the photon sensor or APD to generate a light current, which flows into the MOSFET drain. This forms a positive feedback control loop. When the MOSFET is turned off, both laser and APD are turned off. A photonic CMOS QCL is regulated by a MOSFET, which operates with electric fields, and avalanche breakdown (with APD), which also depends on electric fields. A traditional QCL is based on quantum well diodes, which rely on thermal diffusion to function, and can be easily affected by temperature variations. In this paper we discuss advantages of photonic CMOS QCL vs. traditional QCL.

By modeling, the potential barrier effect on the electroluminescence wavelength spread was determined and QW thickness was determined as well. It was achieved during the laser heterostructures growth by MOCVD. The theoretical model was verified by experimental obtained results. For samples grown in a process with a high growth stability rate, a larger spread in the electroluminescence wavelength was detected for a sample with a smaller Al atoms fraction in the barrier layer