Yacine Halioua

Hybrid III-V semiconductor/silicon nanolaser

Heterogeneous integration of III-V compound semiconductors on Silicon on Insulator is one the key technology for next-generation on-chip optical interconnects. In this context, the use of photonic crystals lasers represents a disruptive solution in terms of footprint, activation energy and ultrafast response. In this work, we propose and fabricate very compact laser sources integrated with a passive silicon waveguide circuitry. Using a subjacent Silicon-On-Insulator waveguide, the emitted light from a photonic crystal based cavity laser is efficiently captured. We study experimentally the evanescent wave coupling responsible for the funneling of the emitted light into the silicon waveguide mode as a function of the hybrid structure parameters, showing that 90% of coupling efficiency is possible.

Heterogeneous integration and precise alignment of InP-based photonic crystal lasers to complementary metal-oxide semiconductor fabricated silicon-on-insulator wire waveguides

The integration of two-dimensional III-V InP-based photonic crystal and silicon wire waveguides is achieved through an accurate alignment of the two optical levels using mix-and-match deep ultraviolet (DUV)/electron beam lithography. The adhesively bonded structures exhibit an enhancement of light emission at frequencies where low group velocity modes of the photonic crystal line defect waveguides occur. Pulsed laser operation is obtained from these modes at room temperature under optical pumping. The laser light is coupled out of the Si waveguide via grating couplers directly to single mode fiber.

Hybrid InP-based photonic crystal lasers on silicon on insulator wires

We report on InP-based photonic crystal lasers operating at 1.585 μm at room temperature, integrated with and evanescently coupled to silicon on insulator (SOI) waveguides. By optically pumping at 1.18 μm through the SOI wires, pulsed laser emission from line defect photonic crystal waveguides accurately aligned (<30 nm) to the silicon circuitry is demonstrated.

Field localization and enhancement of phase-locked second- and third-order harmonic generation in absorbing semiconductor cavities

We predict and experimentally observe the enhancement by three orders of magnitude of phase mismatched second and third harmonic generation in a GaAs cavity at 650 and 433 nm, respectively, well above the absorption edge. Phase locking between the pump and the harmonics changes the effective dispersion of the medium and inhibits absorption. Despite hostile conditions the harmonics resonate inside the cavity and become amplified leading to relatively large conversion efficiencies. Field localization thus plays a pivotal role despite the presence of absorption, and ushers in a new class of semiconductor-based devices in the visible and uv ranges.

Radiation patterns from coupled photonic crystal nanocavities

We report on far field measurements on two coupled photonic crystal nanocavities. The distinct features of the antisymmetric modes (minima of intensity at zero-emission angles) allow us to demonstrate a π-phase difference between the cavity fields, a clear signature of evanescent coupling. Good agreement between experimental results and simulated radiation patterns has been found.

Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range

We demonstrate efficient surface-emitting terahertz frequency quantum cascade lasers with continuous wave output powers of 20–25 mW at 15 K and maximum operating temperatures of 80–85 K. The devices employ a resonant-phonon depopulation active region design with injector, and surface emission is realized using resonators based on graded photonic heterostructures (GPHs). GPHs can be regarded as energy wells for photons and have recently been implemented through grading the period of the photonic structure. In this paper, we show that it is possible to keep the period constant and grade instead the lateral metal coverage across the GPH. This strategy ensures spectrally single-mode operation across the whole laser dynamic range and represents an additional degree of freedom in the design of confining potentials for photons.

Phase-locked arrays of surface-emitting graded-photonic-heterostructure terahertz semiconductor lasers

We have demonstrated that a hybrid laser array, combining graded-photonic-heterostructure terahertz semiconductor lasers with a ring resonator, allows the relative phase (either symmetric or anti-symmetric) between the sources to be fixed by design. We have successfully phase-locked up to five separate lasers. Compared with a single device, we achieved a clear narrowing of the output beam profile.

Stable single-mode operation of surface-emitting terahertz lasers with graded photonic heterostructure resonators

Graded photonic heterostructures (GPH) can be regarded as energy wells for photons. We show that judicious engineering of such photonic wells, obtained by tailoring the grading and the slit width of the GPH resonator, allows one to ensure spectrally single-mode emission on the fundamental symmetric mode in the whole lasing dynamical range of terahertz quantum cascade lasers. Furthermore, the radiative character of the symmetric mode leads to single-mode emission with mW output power in continuous-wave operation, as well as to single-lobed far-field beam patterns. A careful combination of theoretical analysis and experimental observations reveals that the results stem from interplay between mode competition and spatial hole burning effects.

III–V photonic crystal lasers heterogeneously bonded to Silicon-On-Insulator waveguides

We report on the fabrication of InP-based 2D photonic crystal lasers operating around λ = 1.55 µm at room temperature, integrated with and evanescently coupled to Silicon-On-Insulator waveguides. Pulsed laser operation is obtained from a line defect photonic crystal waveguide accurately aligned (≪ 30 nm) on top the SOI circuitry. This active-passive integration is demonstrated using an adhesive bonding technique. Lasing action is demonstrated for several low group velocity modes of the photonic crystal defect waveguide.

Phase-locking of surface-emitting THz quantum cascade laser arrays

We first discuss and review a novel technique to obtain efficient surface-emission in terahertz quantum cascade lasers (THz-QCLs). We report high-power, single-mode surface-emission by using graded photonic heterostructures (GPH) as resonators. Peak output powers of ~100 mW and differential efficiency of 230mW/A are achieved at frequency ~ 3.4THz, the maximum operation temperature being 120K in pulsed mode. Combining with the active region based on the bound-to-continuum design, we also achieved continuous-wave (CW) operation of GPH THz QC lasers, with the maximum output power of 3.8 mW at 2.7THz. We then discuss the prospects to develop phase-locked arrays of these devices, in order to take advantage of their good wall-plug efficiency (<0.3%) and single-lobed directional beam pattern. As an initial result, a very robust approach to phase-lock second-order distributed feedback (DFB) THz QC laser arrays (pairs in this case) is demonstrated.