We fabricated GaInAsP/InP waveguide-integrated lateral-current-injection (LCI) membrane distributed feedback (DFB) lasers on a Si substrate by using benzocyclobutene (BCB) adhesive bonding for on-chip optical interconnection. The integration ofa butt-jointed built-in (BJB) GaInAsP passive waveguide was performed by organometallic vapor-phase epitaxy (OMVPE).By introducing a strongly index-coupled DFB structure with a 50-µm-long cavity, a threshold current of 230 µA was achieved for a stripe width of 0.8 µm under room-temperature continuous-wave (RT-CW) conditions. The maximum output power of 32 µW was obtained. The lasing wavelength and submode suppression ratio (SMSR) were 1534 nm and 28 dB, respectively, at a bias current of 1.2 mA.

We report the first demonstration of direct modulation of InAs/GaAs quantum dot (QD) lasers grown on on-axis (001) Si substrate. A low threading dislocation density GaAs buffer layer enables us to grow a high quality 5-layered QD active region on on-axis Si substrate. The active layer has p-modulation doped GaAs barrier layers with a hole concentration of 5 × 10 cmto suppress gain saturation. Small-signal measurement on a 3 × 580 μm Fabry-Perot laser showed a 3dB bandwidth of 6.5 GHz at a bias current of 116 mA. A 12.5 Gbit/s non-return-to-zero signal modulation was achieved by directly probing the chip. Open eyes with an extinction ration of 3.3dB was observed at room temperature. The bit-error-rate (BER) curve showed no error-floor up to BER of 1 × 10. 12 km single-mode fiber transmission experiments using the QD laser on Si showed a low power penalty of 1 dB at 5Gbit/s. These results demonstrate the potential for QD lasers epitaxially grown on Si to be used as a low-cost light source for optical communication systems.

We demonstrate 10 Gbit/s operation of InAs/InGaAs quantum dot (QD) p-i-n photodiodes (PDs) grown on on-axis (001) GaP/Si substrates. A 3.0 × 50 μm2 QD PD shows a small dark current of 0.2 nA at a bias voltage of −3 V, which corresponds to a dark current density of 0.13 mA/cm2. This low-dark current characteristic obtained from a narrow-stripe device indicates that sidewall and threading dislocations have small effects on the dark current. The 3 dB bandwidth was 5.5 GHz at a bias voltage of −5 V. Large signal measurement with non-return-to-zero signals shows 10 Gbit/s eye opening.

The in-plane and interlayer waveguide-type couplers between crystalline Si and amorphous-Si:H wire waveguides, for 2D/3D hybrid-material integration are presented in this paper. The in-plane-type coupler achieves stable coupling between two waveguides by using tapers located at the tips of the waveguides. The interlayer-type coupler can connect two waveguides, despite an interlayer distance of 1 μm, with a simple process flow, by introducing a trident structure. An experiment was conducted in which the in-plane and interlayer-type couplers realized low coupling losses (coupling efficiencies) of 0.16 dB (96%) and 0.49 dB (89%) per coupler, respectively. Index Terms-a-Si:H waveguide, multilayer, nonlinearity, trident I. INTRODUCTION N optical interconnection is regarded as an effective technique that can realize larger-capacity and higher-speed transmissions, when compared to conventional electrical wiring. In order to realize a large-capacity optical interconnection, silicon photonics is an essential component technology; the core materials are crystalline silicon (c-Si) and silicon dioxide. Silicon photonics is compatible with CMOS fabrication processes, and its high refractive-index contrast structures allow for a small footprint [1]. So far, a number of c-Si based devices such as low-loss wire waveguides, passive devices [2], and active devices including modulators exist [3], [4]. However, c-Si does not meet the requirements for some complex optical devices and systems because of its material properties. Unfortunately, c-Si has a poor luminescence property [5] and high optical nonlinearity [6]. In addition, it cannot be stacked as a multilayer owing to the high M anuscript received Xxx x, xxxx; revised Xxx xx, xxxx and Xxx xx, xxxx; accepted Xxx xx, xxxx. Date of publication Xxx xx, xxxx; date of current version Xxx x, xxxx.

Nonvolatile optical switches are promising components for low-power photonic integrated circuits with multiple functionalities. In this study, we experimentally demonstrate magneto-optical switches integrated with a magnet array. Optical switches in both microring and Mach–Zehnder configurations are fabricated on a high-quality single-crystalline magneto-optical material Ce:YIG. The switched state is alternated by a current-induced magnetic field from an integrated electromagnet and remained without any external power supply owing to the nonvolatile magnetization of thin-film magnets. Subsequently, the arbitrary level control of optical transmission is demonstrated by changing the magnetization state of integrated thin-film magnets with a current applied in the microring gate switch, and a maximum switching ratio over 25 dB is achieved in the Mach–Zehnder switch. The latching operation is presented with a 1-µs pulsed voltage.