Badhise Ben Bakir

Hybrid III--V on Silicon Lasers for Photonic Integrated Circuits on Silicon

This paper summarizes recent advances of integrated hybrid InP/SOI lasers and transmitters based on wafer bonding. At first the integration process of III-V materials on silicon is described. Then the paper reports on the results of single wavelength distributed Bragg reflector lasers with Bragg gratings etched on silicon waveguides. We then demonstrate that, thanks to the high-quality silicon bend waveguides, hybrid III-V/Si lasers with two integrated intra-cavity ring resonators can achieve a wide thermal tuning range, exceeding the C band, with a side mode suppression ratio higher than 40 dB. Moreover, a compact array waveguide grating on silicon is integrated with a hybrid III-V/Si gain section, creating a wavelength-selectable laser source with 5 wavelength channels spaced by 400 GHz. We further demonstrate an integrated transmitter with combined silicon modulators and tunable hybrid III-V/Si lasers. The integrated transmitter exhibits 9 nm wavelength tunability by heating an intra-cavity ring resonator, high extinction ratio from 6 to 10 dB, and excellent bit-error-rate performance at 10 Gb/s.

Quasi-3D Light Confinement in Double Photonic Crystal Reflectors VCSELs for CMOS-Compatible Integration

A novel architecture of one-dimensional photonic crystal membrane (PCM) reflectors embodying a heterostructure is proposed as a robust design aimed at a 3-D efficient confinement of light in single-mode polarization-controlled 1.55-μm vertical-cavity surface-emitting laser (VCSEL) microsources for heterogeneous integration on complementary metal-oxide-semiconductor (CMOS). On the basis of a theoretical approach, the paper focuses on the deep interweaving between the kinetics of light transport in the mirrors and the physical nature of the exploited Fano resonances. An example of VCSEL design for optical pumping employing heterostructure-confined photonic crystal mirrors is presented. The predicted photons kinetics along with the considerable improvement in cavity modal features owing to the enhanced mirror architecture have been confirmed by performing rigorous three-dimensional finite-difference time-domain (3-D FDTD) calculations. Finally, experimental observations of photoluminescence (PL) emission performed on first-ever fabricated devices for optical pumping show striking agreement with theoretical considerations and ab initio modelling.

1310 nm hybrid InP/InGaAsP on silicon distributed feedback laser with high side-mode suppression ratio

We report on the design, fabrication and performance of a hetero-integrated III-V on silicon distributed feedback lasers (DFB) at 1310 nm based on direct bonding and adiabatic coupling. The continuous wave (CW) regime is achieved up to 55 °C as well as mode-hop-free operation with side-mode suppression ratio (SMSR) above 55 dB. At room temperature, the current threshold is 36 mA and the maximum coupled power in the silicon waveguide is 22 mW.

III-V-on-Si Photonic Crystal Vertical-Cavity Surface-Emitting Laser Arrays for Wavelength Division Multiplexing

Double photonic crystal mirror vertical-cavity surface-emitting laser (PCM-VCSEL) arrays for the heterogeneous integration on a complementary metal-oxide semiconductor are presented. The trimming of one-dimensional photonic crystal mirrors spectral and modal features allows a fine tailoring of the lightwave which results in compact VCSEL arrays exhibiting a fully controllable dense wavelength distribution. Optically pumped double PCM-VCSELs emit 1.55-μm single-mode beams within the C-band with sub-milliwatt thresholds and spectral purity, making these devices highly suitable for telecommunication-oriented applications. The intrinsic capability exhibited by PCM-VCSEL arrays for a selective addressing of dense wavelength division multiplexing (DWDM) channels suggests a strong perspective potential for several applications such as high-capacity ultra-wideband optical interconnects, passive optical networks, free-space data transmission and sensing.

Toward athermal silicon-on-insulator (de)multiplexers in the O-band.

We report on the design, fabrication, and characterization of a 1×4 silicon-on-insulator (SOI) demultiplexer exhibiting a significant reduction of its thermo-optical sensitivity in the O-band. The optical filtering is achieved by cascading several Mach-Zehnder interferometers (MZIs) fabricated on a 300-nm-thick SOI platform. Owing to an asymmetric design of the confinement for each MZIs, we found an athermal criterium that satisfies the spectral requirements. The thermal sensitivity of the structure is analyzed by a semi-analytical model in order to create an athermal multiplexer. Fiber-to-fiber thermo-optical testing reveals a thermal sensitivity of around 17  pm/°C reduced by 75% compared to the standard devices with promising performances for both the crosstalk (15 dB), the insertion losses (4 dB), and absolute lambda registration (<0.25  nm).

Double photonic crystal vertical-cavity surface-emitting lasers

The periodic patterning of the optical medium achieved through photonic crystal membranes (PCMs) can be employed for controlling the resonant coupling of external radiation continuum to above-the-light-line flat edges of the folded band structure in strongly corrugated waveguides, resulting in high reflectivity for an efficient quasi-3D light harnessing. Recently, vertical-cavity surface-emitting lasers (VCSELs) emitting in C-band using a double set of one-dimensional Si/SiO2 photonic crystals as compact, flexible, and power efficient mirrors have been realized within a mass-scale fabrication paradigm by employing standard 200-mm microelectronics pilot lines. Conceived as the basic building block for photonics-on-silicon back-end integration of group III-V laser microsources, the extreme flexibility of the novel photonic architecture enables to perform a tailored modal selection of the optical cavity, including polarization and far-field control. It also offers a wide range of functionality, such as on-chip optical routing and a variety of efficient wavelength tuning-trimming schemes. Device compactness ensures a considerable reduction in the device footprint, power consumption, and parasitics. Furthermore, high fabrication yields obtained thanks to the state-of-the-art molecular wafer bonding of III-V alloys on silicon conjugate excellent device performances with cost-effective high-throughput production, indicating strong perspective industrial potential.

Vertical microcavities based on photonic crystal mirrors for III-V/Si integrated microlasers

The on-coming photonic layer of CMOS integrated circuits needs efficient light sources to treat and transmit the flow of data. We develop new configurations of III-V/Si vertical cavity lasers coupled to silicon optical waveguides using mirror/coupler based on photonic crystals. These devices can be fabricated using fully CMOS-compatible technological steps. Using this approach, the optical gain is provided by the III-V material, while all the remaining part of the optical cavity is in silicon. The output coupling to the sub-µm waveguides of the CMOS optical layer can then be inherently optimised since the laser mirror/coupler and the Si output waveguides will be realised together during the same fabrication step. It has been demonstrated that photonic crystals membrane can act as very efficient reflectors (PCM-mirrors) for vertical microresonators. In this communication, the design of a vertical cavity microlaser based on these PCM-mirrors will be presented. We will show that high Q-factors (>10000) along with strong vertical and lateral confinements can be achieved. As a first demonstration, experimental results on silicon PhC-mirrors and associated vertical cavities will be discussed, showing Q factors larger than 2000. Finally, theoretical results on the coupling between such cavities and a silicon micro-waveguide will be presented.

Co-integrated 1.3µm hybrid III-V/silicon tunable laser and silicon Mach-Zehnder modulator operating at 25Gb/s.

In this paper, the 200mm silicon-on-insulator (SOI) platform is used to demonstrate the monolithic co-integration of hybrid III-V/silicon distributed Bragg reflector (DBR) tunable lasers and silicon Mach-Zehnder modulators (MZMs), to achieve fully integrated hybrid transmitters for silicon photonics. The design of each active component, as well as the fabrication process steps of the whole architecture are described in detail. A data transmission rate up to 25Gb/s has been reached for transmitters using MZMs with active lengths of 2mm and 4mm. Extinction ratios of respectively 2.9dB and 4.7dB are obtained by applying drive voltages of 2.5V peak-to-peak on the MZMs. 25Gb/s data transmission is demonstrated at 1303.5nm and 1315.8nm, with the possibility to tune the operating wavelength by up to 8.5nm in each case, by using metallic heaters above the laser Bragg reflectors.

O-Band III–V-on-Amorphous-Silicon Lasers Integrated With a Surface Grating Coupler

In this letter, we report on the design, fabrication, and performance of a hetero-integrated III-V/silicon distributed-feedback (DFB) laser in the O-band, with improved integration compatibility with the existing silicon photonics platforms. This structure uses amorphous silicon deposited at a low temperature (350 °C) to efficiently couple light from the III-V region into a thin silicon-on-insulator waveguide, without disrupting other existing silicon components. Continuous-wave regime is achieved at 25 °C, while lasing threshold and maximum output power in the waveguides are 50 mA and 33.6 mW, respectively. The maximum power coupled into a single-mode fiber at one end of the DFB is up to 4.7 mW.

Surface addressable photonic crystal membrane resonators: generic enablers for 3D harnessing of light

Conceptual approaches used to analyse optical properties of surface-addressable photonic crystal membrane (PCM) resonators will be briefly presented. It will be pointed out that these photonic structures can also be referred to as high-contrast gratings (HCGs) and that bridges can be made with other approaches proposed in the recent literature to analyse the latter. It will be demonstrated that high reflection mirrors, with arbitrarily adjustable bandwidth, can be designed along the PCM approach, where leaky wave-guided slow Bloch modes play the primary role. Implementation examples of such reflectors are presented, with a special emphasis on the use of large bandwidth PCM reflector: vertical-cavity surface-emitting lasers (VCSELs) using hybrid III-V / Si microcavities, based on double PCM reflectors, have been recently fabricated. These devices are meant to be compatible with their heterogeneous integration on complementary metal-oxide-silicon (CMOS). It will be shown that the operation of this new class of VCSEL is based on hybrid optical modes, whose properties can be fully monitored by appropriate design of the PCM reflectors. For example, specific architectures can be targeted for laser emission either in free space, or into silicon waveguides. The latest achievements in technological processing, optical mode engineering and laser performances will be presented as well.