Masashige Ishizaka

First demonstration of high density optical interconnects integrated with lasers, optical modulators, and photodetectors on single silicon substrate

Optical interconnects integrated with lasers, silicon optical modulators and germanium photodetectors on a single silicon substrate were demonstrated for the first time. A 5 Gbps line bit rate and 3.5 Tbps/cm2 transmission density were achieved.

Compact, lower-power-consumption wavelength tunable laser fabricated with silicon photonic-wire waveguide micro-ring resonators.

A wavelength tunable laser with an SOA and external double micro-ring resonator, which is fabricated with silicon photonic-wire waveguides, is demonstrated. To date, it is the first wavelength tunable laser fabricated with silicon photonic technology. The device is ultra compact, and its external resonator footprint is 700 x 450 microm, which is about 1/25 that of conventional tunable lasers fabricated with SiON waveguides. The silicon resonator shows a wide tuning range covering the C or L bands for DWDM optical communication. We obtained a maximum tuning span of 38 nm at a tuning power consumption of 26 mW, which is about 1/8 that of SiON-type resonators.

A Hybrid Integrated Light Source on a Silicon Platform Using a Trident Spot-Size Converter

This paper reports a hybrid integrated light source fabricated on a Si platform using a spot-size converter (SSC) with a trident Si waveguide. Low-loss coupling for 1.55 μm and 1.3 μm wavelengths was achieved with merely the simple planar form of a Si waveguide with no use of complicated structures such as vertical tapers or an extra dielectric core overlaid on the waveguide. The coupling loss tolerance up to a 1 dB loss increase was larger than the accuracy of our passive alignment technology. The coupling efficiency was quite robust against manufacturing variations in the waveguide width compared with that of a conventional SSC with an inverse taper waveguide. A multi-channel light source with highly uniform output power and a high-temperature light source were fabricated with a 1.55 μm quantum well laser and a 1.3 μm quantum dot laser, respectively. The integration scheme we report can be used to fabricate light sources for high-density, multi-channel Si optical interposers.

High density hybrid integrated light source with a laser diode array on a silicon optical waveguide platform for inter-chip optical interconnection

A hybrid integrated light source was developed with a novel configuration in which a laser diode (LD) array was mounted on a silicon optical waveguide platform for inter-chip optical interconnection. An output power uniformity of 1.3 dB was observed at the 13-channel integrated light source with 30-µm pitch. Use of a SiON waveguide with a spot size converter resulted in an optical coupling loss of 1 dB between an LD and a SiON waveguide. The integrated light source including 52 output ports was demonstrated to reduce the footprint per channel. These integrated light sources are attractive candidates for use with photonic integrated circuits for high density optical interconnection.

1.52-1.59-μm range different-wavelength modulator-integrated DFB-LDs fabricated on a single wafer

We report for the first time different-wavelength modulator-integrated distributed-feedback laser diodes (DFB/MODs) fabricated on a single wafer, whose lasing wavelength cover almost all of the expanded erbium-doped fiber amplifier (EDFA) gain band from 1.527 to 1.593 /spl mu/m. The devices provided uniform and high-performance characteristics such as a threshold current less than 12 mA and successful transmission of 2.5 Gb/s-600 km through a normal fiber.

A stable widely tunable laser using a silica-waveguide triple-ring resonator

A tunable laser consisting of a silica-waveguide triple-ring resonator connected directly to a semiconductor optical amplifier is presented. Stable single-mode, grid-hopping free and full-band wavelength-digitally-tuning operations with 50-GHz channel spacing are successfully demonstrated.

A novel spot size convertor for hybrid integrated light sources on photonics-electronics convergence system

We have developed a spot size converter (SSC) with a trident silicon (Si) waveguide for the hybrid integrated light source in a photonics-electronics convergence system. Low loss coupling was achieved with just the simple planar form of a Si waveguide with no use of complicated structures such as vertical tapers or extra dielectric core overlaid on the waveguide. The coupling loss was 2.3 dB and the tolerance of misalignment up to a 1-dB loss increase was about ± 0.9 μm. We also confirmed that the coupling efficiency was quite robust against manufacturing fluctuations of the waveguide width compared with a conventional SSC with an inverse taper waveguide. We were able to fabricate a 52-channel light source with highly uniform output power by using the proposed trident SSC.

Ultra-small one-chip color-less multiplexer/demultiplexer using silicon photonic circuit

Using silicon waveguides, an arrayed waveguide grating and switches are integrated into one chip. Low-power and fast-speed reconfigurability of optical paths within a 2-mm device is demonstrated.

The transmission capability of a 10-Gb/s electroabsorption modulator integrated DFB laser using the offset bias chirp reduction technique

The transmission capability using the offset bias chirp reduction technique of a 10-Gb/s modulator-integrated DFB laser is evaluated using transmission simulation, taking into account modulation-induced dynamic chirping. The calculated results indicate the feasible transmission distance over normal dispersion fibers is 120 km with optimizing wavelength detuning, and 80 km for practical use.

Differential signal transmission in silicon-photonics integrated circuit for high density optical interconnects

Differential signal transmission is demonstrated for high-density optical interconnects by a silicon-photonics integrated circuit, in which arrayed lasers, silicon optical modulators (Si-MODs) and germanium photodetectors (Ge-PDs) are integrated on a single silicon substrate. 3 dB gain of output signal-intensity was obtained and about 40 dB suppression of electrical cross-talk between a Si-MOD and a Ge-PD was obtained at GHz range. A lower bit-error-rate of data transmission and enhanced sensitivity of around 2 dB were achieved at 2 Gbps.