We demonstrate an ultra-fast athermal continuous wavelength-swept III-V-on-SOI MOSCAP DFB laser with a mode-hop-free-tuning up to 10 GHz in less than 2 ns. We also propose a new method to linearize the frequency response without any pre-distortion or active feedback in the gain’s current injection ramp. Instead, we polarize the III-V gain Section under direct current injection, and we drive the hybrid MOSCAP waveguide with an AC voltage signal. By optimizing its driving frequency, we demonstrate an ultra-fast athermal triangular-shaped time-varying frequency tuning with a speed of $4\times 10 ^{4}$ PHz/s and a laser’s frequency excursion of 4 GHz.

The integration of active devices such as lasers, modulators or photodetectors on silicon photonics platforms has enabled the development of efficient, performant, low-cost and scalable high-speed integrated transceivers for optical communications. In this invited contribution, we will review the most relevant work in the field so far and we will present our recent progress on high-speed integrated transceivers for silicon photonics. The most relevant figures of merit for integrated lasers and electro-absorption modulators for high-speed optical communications will be discussed, as well as our vision for future developments.

The field of Silicon Photonics has experienced a solid and continuous progress over the last few years, gaining in technological maturity, design tools, and new methods [1]. The deployment of low-cost, compact, and power-efficient photonic circuits with a high wafer yield and robustness stands as one of the fundamental pillars that sustain such progress [2]. Presently, photonic circuit technology has diversified its number of available platforms. Despite the fact that indium phosphide (InP) [3] and silicon-on-insulator (SOI) platforms are still considered as the workhorses of integrated photonics in terms of maturity and deployment of active (InP) and passive (SOI) components, other alternatives such as germanium-on-silicon [4], silicon nitride-on-insulator [2] or hybrid solutions combining different functional materials with Si are gaining momentum [5]. A representative example is the heterogeneous III-V/Si platform [6], which has been used to develop compact photonic circuits with on-chip gain. Contrarily to the hybrid integration, the III-V-on-Si heterogeneous integration avoids the constraints of chip-to-chip alignment while enabling the simultaneous integration of hundreds of III-V gain chips in a scalable fashion. Still, the integration methods of such III-V materials on silicon need to be improved to attain the maturity level of the monolithic III-V platform, which benefits from a complete palette of technological solutions not yet available in the III-V-on-Si heterogeneous integration. More recently, an advanced heterogeneous scheme based on wafer-seed-bonding and epitaxial regrowth has emerged [7]–[9]. The ambition is to create a generic integration scheme combining the best offered by the III-V and the Si-photonics platforms. The regrowth capability gives access to the large epitaxial toolkit available in the conventional InP monolithic platform, where several epitaxial steps are often implemented [10][11]. To cite some of them, the epitaxial regrowth of III-V materials to bury III-V lasers bonded onto silicon are object of intense research nowadays to overcome the thermally inefficient buried oxide [12]. In this paper, we will review the advances on III-V-on-Si heterogeneous integration through the implementation of several key demonstrators and building blocks for silicon photonics, including on-chip semiconductor optical amplifiers, lasers and electro-absorption modulators. We will discuss the progress and benefits of the direct seed bonding and regrowth as well as new device designs to improve the performance. References: [1] D. Thomson et al. , “Roadmap on silicon photonics,” J. Opt. , vol. 18, no. 7, p. 73003, 2016, doi: 10.1088/2040-8978/18/7/073003. [2] S. Y. Siew et al. , “Review of Silicon Photonics Technology and Platform Development,” Journal of Lightwave Technology , vol. 39, no. 13. Institute of Electrical and Electronics Engineers Inc., pp. 4374–4389, Jul. 01, 2021, doi: 10.1109/JLT.2021.3066203. [3] M. Smit, K. Williams, and J. Van Der Tol, “Past, present, and future of InP-based photonic integration,” APL Photonics , vol. 4, no. 5, May 2019, doi: 10.1063/1.5087862. [4] J. Chrétien et al. , “GeSn Lasers Covering a Wide Wavelength Range Thanks to Uniaxial Tensile Strain,” ACS Photonics , vol. 6, no. 10, pp. 2462–2469, Oct. 2019, doi: 10.1021/acsphotonics.9b00712. [5] S. Lin et al. , “Efficient, tunable flip-chip-integrated III-V/Si hybrid external-cavity laser array,” Opt. Express , vol. 24, no. 19, p. 21454, Sep. 2016, doi: 10.1364/oe.24.021454. [6] D. Liang and J. E. Bowers, “Recent Progress in Heterogeneous III-V-on-Silicon Photonic Integration,” Light Adv. Manuf. , vol. 2, no. 1, pp. 1–25, 2021, doi: 10.37188/lam.2021.005. [7] K. Takeda, S. Matsuo, T. Fujii, K. Hasebe, T. Sato, and T. Kakitsuka, “Epitaxial growth of InP to bury directly bonded thin active layer on SiO2/Si substrate for fabricating distributed feedback lasers on silicon,” IET Optoelectron. , vol. 9, no. 4, pp. 151–157, 2015, doi: 10.1049/iet-opt.2014.0138. [8] C. Besancon et al. , “AlGaInAs Multi-quantum Well Lasers On Silicon-on-insulator Photonic Integrated Circuits Based On InP-seed-bonding And Epitaxial Regrowth,” Appl. Sci. , vol. 12, no. 1, Jan. 2022, doi: 10.3390/app12010263. [9] Y. Hi et al. , “Electrically-Pumped 1.31 μm MQW Lasers by Direct Epitaxy on Wafer-Bonded InP-on-SOI Substrate,” in Proceedings of 2018 IEEE Photonics Conference (IPC) , 2018, pp. 1–2. [10] V. Rustichelli et al. , “Monolithic integration of buried-heterostructures in a generic integrated photonic foundry process,” IEEE J. Sel. Top. Quantum Electron. , vol. 25, no. 5, Sep. 2019, doi: 10.1109/JSTQE.2019.2927576. [11] F. Lemaître et al. , “96 nm Extended Range Laser Source Using Selective Area Growth,” in European Conference on Optical Communication, ECOC , 2018, doi: 10.1109/ECOC.2018.8535218. [12] C. Besancon et al. , “AlGaInAs Multi-Quantum Well Laser on Silicon Achieved byDirect-Bonding and MOVPE Semi-Insulating Buried Heterostructure Regrowth,” in Compound Semiconductor Week 2023 , Jan. 2023, vol. 12, no. 1, doi: 10.3390/app12010263.

Heterogeneous integration of III-V materials on silicon photonics circuits has emerged as an attractive approach to demonstrate compact lasers that address a wide range of applications ranging from short distance data communication to long distance optical transmission. Directly modulated III-V-on-SOI lasers (DML) with high bandwidths such as distributed feedback (DFB) lasers are particularly well suited for those applications that require high optical power and stable single-mode performance [1].

We review our work on integrated lasers for optical communications. An InP-based multilayer stack containing Al-based quantum wells with optical gain in the telecom window is bonded onto a silicon-on-insulator wafer with patterned photonic circuits and cavities. Ring-based widely tunable lasers and narrow linewidth DFB lasers are demonstrated.

We demonstrate stable operation of a multimode DFB laser-based on a 1D photonic crystal cavity. The laser signal comprises three modes spaced by similar to 28 GHz with linewidths below 135 kHz. Under mode-locking operation, the laser beat tone is narrowed down to 20 kHz. (C) 2022 The Author(s)

Heterogeneous integration of III-V on silicon lasers eliminates some constraints of chip-to-chip alignment, but the optical coupling between the two media remains of importance for repeatable performances. First, we present a processing enhancement of the bonding oxide thickness uniformity across the wafer, improving the cross-section reproducibility. Next optimized tapering of the III-V/Si waveguides, offering a design agnostic to the number of quantum wells, will be shown. Finally, the yield of III-V on Silicon tunable lasers was evaluated by mean of wafer level measurements, using a yield oriented tuning of each cavity, so that lasers characteristics can be fairly compared.

We demonstrate a heterogeneously integrated III-V-on-SOI distributed feedback laser with a low grating strength (κ < 40 cm-1) and a narrow linewidth of Δν = 118 kHz. The laser operates single mode with a side-mode suppression ratio over 45 dB, provides a single-sided waveguide-coupled output power of 22 mW (13.4 dBm) and has a wall-plug efficiency of 17%. The dynamic characteristics were also evaluated, obtaining an intrinsic 3 dB modulation bandwidth of 14 GHz and a photon lifetime of 8 ps. Large-signal intensity modulation using a 231-1 PRBS pattern length revealed open eye diagrams up to 25 Gb/s and a penalty on the dynamic extinction ratio lower than 1 dB after transmission over a 2 km standard single mode optical fiber.

We demonstrate a heterogeneously integrated III-V/Si capacitive distributed feedback laser, which is continuously tunable across a 10 GHz band in less than 2 ns, with record-low power consumption

In the frame of the H2020 PICTURE project, we designed and developed densely integrated photonic devices and transceiver (TRx) circuits for high bit-rate telecom and datacom applications. We implemented a process with four different InP-based dies bonded on SOI wafers. With one sole back-end processing run, we achieved the fabrication of multiple components of the complex TRx circuits, and many building block devices, such as III-V/Si SOAs & Fabry-Perot lasers, photodiodes or fast tunable capacitive DFB lasers. First testing of these devices shows promising results. 13dBm-saturation power SOAs and less than 2ns-tuning time capacitive DFB lasers were fabricated and demonstrated.