Kasper Van Gasse

A III-V-on-Si ultra-dense comb laser

Optical frequency combs emerge as a promising technology that enables highly sensitive, near-real-time spectroscopy with a high resolution. The currently available comb generators are mostly based on bulky and high-cost femtosecond lasers for dense comb generation (line spacing in the range of 100 MHz to 1 GHz). However, their integrated and low-cost counterparts, which are integrated semiconductor mode-locked lasers, are limited by their large comb spacing, small number of lines and broad optical linewidth. In this study, we report a demonstration of a III-V-on-Si comb laser that can function as a compact, low-cost frequency comb generator after frequency stabilization. The use of low-loss passive silicon waveguides enables the integration of a long laser cavity, which enables the laser to be locked in the passive mode at a record-low 1 GHz repetition rate. The 12-nm 10-dB output optical spectrum and the notably small optical mode spacing results in a dense optical comb that consists of over 1400 equally spaced optical lines. The sub-kHz 10-dB radio frequency linewidth and the narrow longitudinal mode linewidth (<400 kHz) indicate notably stable mode-locking. Such integrated dense comb lasers are very promising, for example, for high-resolution and real-time spectroscopy applications.

16 Gbps RoF link at 20 ghz carrier frequency using a silicon photonics transmitter and receiver

In future radio access networks, radio-over-fiber links will be a key enabling technology. A link which is cost-effective in both deployment and operation will be of paramount importance to the development of such networks. Using silicon photonics for the transmitter and receiver is a cost-effective and high-performance solution. In this work we present a link which can transport up to 16 Gbps 16-QAM data on a 20 GHz carrier over 5 km of SMF. The transmitter is a III-V-on-Si directly modulated laser and the receiver is a Ge-on-Si photodetector on a silicon photonic integrated circuit, co-integrated with a SiGe BiCMOS TIA. This is to the best of our knowledge the first Si PIC based RoF link with a directly modulated laser.

Resonantly enhanced silicon photonics Mach-Zehnder modulator

In this work we present the design, fabrication and characterization of a silicon photonics Mach-Zehnder modulator (MZM) with resonant electrode. The device shows an enhanced modulation response in the 20GHz frequency range compared to a standard traveling-wave MZM.

Ka-to-l-band frequency down-conversion using a micro-photonic III-V-on-silicon mode-locked laser and Mach-Zehnder modulator

RF frequency down-conversion is of key importance in communication satellites. While the available high-end microwave electronic mixers and circuitry are bulky, heavy, expensive and sensitive to electromagnetic interference (EMI), microwave photonics emerges to be a promising and low-cost alternative.