We report the experimental demonstration of a new design for external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier (SOA) with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB. © 2015 Optical Society of America Over the past few years, Silicon (Si) Photonics technology has emerged as a potential solution for the realization of low-cost, high performance components and Photonic Integrated Circuits (PIC) that can be used to meet the increasing bandwidth demands of chip-scale and on-chip optical interconnections [1][2][3][4]. A key feature of PICs is their ability to support Wavelength Division Multiplexing (WDM), a technique offering the parallelism necessary for high bandwidth and high density chips. Cheap, compact, efficient and Silicon compatible wavelength-tunable laser sources with precise wavelength control are thus crucial elements to facilitate the generation of WDM optical interconnects [5].Although Silicon-On-Insulator (SOI) has proven itself to be a most appealing platform for light propagation and manipulation, practical efficient, electrically pumped lasers directly in Si or other group IV elements are still absent from the Silicon Photonics tool kit, owing to the indirect bandgap that these materials exhibit. Consequently, the use of III-V elements as gain material in lasers for WDM optical interconnects is dictated -a challenging task, as direct growth of III-V semiconductors on IV semiconductors is difficult due to lattice constant mismatch and compatibility issues.A popular solution to the above problem is the heterogeneous integration of III-V parts on top of SOI PICs by means of direct wafer bonding [6]. An alternative approach suggests the deployment of Reflective Semiconductor Optical Amplifiers (RSOAs) and external Si-based reflectors for the formation of External-Cavity (EC) lasers. The latter approach has lately attracted significant attention as it allows independent design, fabrication and optimization of the active and the passive regions, and makes the most effective use of the III-V materials [5,7]. Up to now, devices that use Bragg gratings [7][8][9], ring resonators [10,11] and Sagnac interferometers [12] as Si reflectors have been demonstrated in this platform.The concept of using grating cavity resonant mirrors for Tx Rx heterogeneously integrated lasers has been introduced in [13, 14]. In this Letter, we present an EC laser design employing as a resonant reflector a PhC cavity coupled to a low-index waveguide [15,16], which lays the first stone towards EC laser source architectures with small footprint, high Side-Mode Suppression Ratio (SMSR), and the highly precise wavelength control required for WDM applications [5]. The Si-based reflector is simply a d...

The need for miniaturized, fully integrated semiconductor lasers has stimulated significant research efforts into realizing unconventional configurations that can meet the performance requirements of a large spectrum of applications, ranging from communication systems to sensing. We demonstrate a hybrid, silicon  photonics-compatible photonic crystal (PhC) laser architecture that can be used to implement cost-effective, high-capacity light sources, with high side-mode suppression ratio and milliwatt output output powers. The emitted wavelength is set and controlled by a silicon PhC cavity-based reflective filter with the gain provided by a III–V-based reflective semiconductor optical amplifier (RSOA). The high power density in the laser cavity results in a significant enhancement of the nonlinear absorption in silicon in the high Q-factor PhC resonator. The heat generated in this manner creates a tuning effect in the wavelength-selective element, which can be used to offset external temperature fluctuations without the use of active cooling. Our approach is fully compatible with existing fabrication and integration technologies, providing a practical route to integrated lasing in wavelength-sensitive schemes.

Tunable on-chip optical delay has long been a key target for the research community, as it is the enabling technology behind delay lines, signal re-timing and other applications vital to optical signal processing. To date the field has been limited by high optical losses associated with slow light or delay structures. Here, we present a novel tunable delay line, based on a coupled cavity system exhibiting an Electromagnetically Induced Transparency-like transmission spectrum, with record low loss, around 15dB/ns. By tuning a single cavity the delay of the complete structure can be tuned over 120ps, with the maximum delay approaching 300ps.

The authors present results on the performance of a hybrid external cavity photonic crystal laser-comprising semiconductor optical amplifier, and a 2D photonic crystal cavity fabricated in low-temperature amorphous silicon. The authors demonstrate that lithographic control over amorphous silicon photonic crystal cavity-resonant wavelengths is possible, and that single-mode lasing at optical telecommunications wavelengths is possible on an amorphous silicon platform.