Abstract-We have designed and fabricated an out-of-plane coupler for butt-coupling from fiber to compact planar waveguides. The coupler is based on a short second-order grating or photonic crystal, etched in a waveguide with a low-index oxide cladding. The coupler is optimized using mode expansion-based simulations. Simulations using a 2-D model show that up to 74% coupling efficiency between single-mode fiber and a 240-nm-thick GaAs-AlO waveguide is possible. We have measured 19% coupling efficiency on test structures.Index Terms-Integrated optics, optical planar waveguide components, waveguide coupler.

A compact, electrically driven light source integrated on silicon is a key component for large-scale integration of electronic and photonic integrated circuits. Here we demonstrate electrically injected continuouswave lasing in InP-based microdisk lasers coupled to a sub-micron silicon wire waveguide, fabricated through heterogeneous integration of InP on silicon-on-insulator (SOI). The InP-based microdisk has a diameter of 7.5 μm and a thickness of 1 μm. A tunnel junction was incorporated to efficiently contact the p-side of the pn-junction. The laser emits at 1.6 μm, with a threshold current as low as 0.5 mA under continuous-wave operation at room temperature, and a threshold voltage of 1.65 V. The SOI-coupled laser slope efficiency was estimated to be 30 μW/mA, with a maximum unidirectional output power of 10 μW.

Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc. ID XXXXX); published Month X, XXXX Heterogeneously integrated III-V-on-silicon second order distributed feedback lasers utilizing an ultra-thin DVS-BCB die-to-wafer bonding process are reported. A novel design exploiting high confinement in the active waveguide is demonstrated. 14mW output power coupled to a silicon waveguide, 50dB side mode suppression ratio and continuous wave operation up to 60°C is obtained. Silicon photonics is emerging as an important platform for the realization of high-speed optical transceivers. This is related to the fact that the silicon waveguide circuits, comprising ultra-compact passive waveguide circuitry, high-speed optical modulators and germanium photodetectors, can be fabricated using complementary metal-oxide-semiconductor (CMOS) fabrication technology in large volumes and at low cost [1]. However, the integration of a coherent light source on the silicon platform remains an issue. While electrically driven germanium laser sources have been demonstrated [2], the performance of these devices is still far inferior to what can be achieved using InP-based III-V semiconductors. III-V semiconductor layer stacks can be heterogeneously integrated onto the silicon waveguide circuit using a wafer bonding technique followed by InP substrate removal, which provides a route towards wafer-scale processing of these III-V epitaxial layers, lithographically aligned to the underlying waveguide circuit. In recent years, several device demonstrations were made on this III-V/silicon platform [3], both using a molecular [4] and adhesive bonding approach [5]. In this paper we describe the realization of single wavelength 1550nm distributed feedback (DFB) lasers coupled to a 220nm thick silicon waveguide layer, with waveguide coupled output powers of 14mW, a side-mode-suppression ratio better than 50 dB and a laser linewidth of 1MHz. The coupling to a 220nm silicon waveguide circuit will allow in a later stage to cointegrate high speed devices such as modulators and photodetectors with the single wavelength lasers using the available silicon photonics platform technology as offered by several multi-project wafer run services worldwide.The distributed feedback laser structures reported in this paper are based on quarter-wave shifted second order gratings with a Bragg wavelength around 1550nm. The three dimensional layout of the laser cavity is depicted in Figure 1(a), while a longitudinal cross-section of the laser geometry is shown in Figure 1(b). The gratings are

Silicon nitride waveguides with a monolayer of colloidal quantum dots embedded inside were fabricated using a low-temperature deposition process and an optimized dry etching step for the composite layers. We experimentally demonstrated the luminescence of the embedded quantum dots is preserved and the loss of these hybrid waveguide wires is as low as 2.69dB/cm at 900nm wavelength. This hybrid integration of low loss silicon nitride photonics with active emitters offers opportunities for optical sources operating over a very broad wavelength range. References and links1. E. S. Hosseini, S. Yegnanarayanan, A. H. Atabaki, M. Soltani, and A. Adibi, "High quality planar silicon nitride microdisk resonators for integrated photonics in the visible wavelength range," Opt.

Abstract:We demonstrate unidirectional bistability in microdisk lasers electrically pumped and heterogeneously integrated on SOI. The lasers operate in continuous wave regime at room temperature and are single mode. Integrating a passive distributed Bragg reflector (DBR) on the waveguide to which the microdisk is coupled feeds laser emission back into the laser cavity. This introduces an extra unidirectional gain and results in unidirectional emission of the laser, as demonstrated in simulations as well as in experiment.

Miniaturized laser Doppler vibrometers (LDVs) have many advantages over conventional bulk LDVs. In this paper, the realization of a miniaturized heterodyne LDV integrated on silicon-on-insulator substrate is reported. The optical frequency shifters in these on-chip LDVs employ a serrodyne technique, and they generate a frequency shift at 2 kHz. Vibrations of a mirror for the frequency range between 1.1 and 123 Hz and the velocity range between 0.8 and 400 μm∕s are measured by both an on-chip LDV and a commercial LDV. The measurement results agree well. A compensation method for the influence of on-chip spurious reflections is also demonstrated.

We present experimental results on the intracavity generation of radially polarized light by incorporation of a polarization-selective mirror in a CO 2 -laser resonator. The selectivity is achieved with a simple binary dielectric diffraction grating etched in the backsurface of the mirror substrate. Very high polarization selectivity was achieved, and good agreement of simulation and experimental results is shown. The overall radial polarization purity of the generated laser beam was found to be higher than 90%.

In this paper we report a single mode InAs/GaAs quantum dot distributed feedback laser at 1.3 μm wavelength heterogeneously integrated on a Si photonics waveguide circuit. Single mode lasing around 1300 nm with a side-mode suppression ratio higher than 40 dB is demonstrated. High temperature operation with continuous wave lasing up to 100°C is obtained. Threshold current densities as low as 205 A/cm were measured. These devices are attractive candidates to use in uncooled silicon photonic transceivers in data centers.