Roel Baets

Nonlinear self-distortion of picosecond optical pulses in silicon wire waveguides

We experimentally observed the self-distortion of picosecond pulses propagating in silicon wire waveguides. The asymmetry of output pulse shape was due to two-photon absorption generated free carriers within the pulse duration.

Supercontinuum generation in hydrogenated amorphous silicon waveguide

We report supercontinuum (SC) generation centered on the telecommunication C-band (1550nm) in CMOS compatible hydrogenated amorphous silicon waveguide. A broadening of 200nm is obtained in a 1cm long waveguide using as pump 1.6ps pulses with on chip peak power of 4,5W and 45W.

III-V/silicon photonic integrated circuits for spectroscopic sensing in the 2um wavelength range

III-V/silicon photonic integrated circuits (ICs) promise to enable low cost and miniature optical sensors for trace-gas detection, bio-sensing and environmental monitoring. A lot of these applications can benefit from the availability of photonic ICs beyond the telecommunication wavelength range. The 2 μm wavelength range is of interest for spectroscopic detection of many important gases and blood constituents. In this contribution we will present 2 μmwavelength-range III-V/silicon photonic ICs consisting of tunable laser sources, photodetectors and silicon waveguide circuits. Silicon waveguides with a loss of ~0.5 dB/cm are obtained in a well-established silicon photonics platform. Based on the waveguides, low insertion loss (2-3 dB) and low crosstalk (25-30 dB) arrayed waveguide gratings (AWGs) are realized for the 2.3 μm wavelength range. Active opto-electronic components are integrated on the photonic IC by the heterogeneous integration of an InP-based type-II epitaxial layer stack on silicon. III-V-on-silicon 2.3 μm range distributed feedback (DFB) lasers can operate up to 25 °C in continuous-wave regime and shows an output power of 3 mW. By varying the silicon grating pitch, a DFB laser array with broad wavelength coverage from 2.28 μm to 2.43 μm is achieved. III-V-on-silicon photodetectors with the same epitaxial layer stack exhibit a responsivity of 1.6 A/W near 2.35 μm. In addition, we also report a 2 μm range GaSb/silicon hybrid external cavity laser using a silicon photonic IC for wavelength selective feedback. A wavelength tuning over 58 nm and side mode suppression ratio better than 60 dB is demonstrated.

Multi quantum well (MQW) lasers at 1550 nm fabricated with a single epitaxial selective growth step by MOVPE without waveguide etching

MQW lasers have been fabricated by means of a single selective epitaxial growth and without waveguide etching. Flat layer interfaces have been obtained for a wide range of mask widths and mask openings while retaining material quality and providing wide bandgap tuning range through the use of QWs. Initial results show good laser performance at 1550 nm demonstrating the feasibility of the easy fabrication method for the realisation of more complex devices by means of active-passive integration.