Germanium-on-silicon thermo-optic phase shifters are demonstrated in the 5 μm wavelength range. Basic phase shifters require 700 mW of power for a 2π phase shift. The required power is brought down to 80 mW by complete undercut using focused ion beam. Finally an efficient thermo-optic phase shifter is demonstrated on the germanium on SOI platform. A tuning power (for a 2π phase shift) of 105 mW is achieved for a Ge-on-SOI structure which is lowered to 16 mW for a free standing phase shifter.

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

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We demonstrate a new kind of single-mode micro-optical waveguide based on a liquid core on top of solid substrate and air cladding. The liquid is held in place by surface tension and patterned surface energy on the substrate. Due to the smooth nature of the liquid/air interface down to the molecular level, low scattering losses are expected. Losses were measured to be -6.0 and -7.8 dB/cm for, respectively, 12 and 9 μm wide waveguides.