Yosuke Onawa

Polarization rotation Bragg diffraction using Si wire waveguide grating and polarization rotator

We report polarization independent Bragg grating wavelength filter with high diffraction efficiency. A rib waveguide polarization rotator and antisymmetric grating structure for fundamental to first order diffraction are used to generate the polarization rotation Bragg diffraction. The diffraction efficiencies and peak wavelengths become the same for two orthogonal input polarizations. Strong diffraction is attained easily. The concept was verified by simulation and experiment. Polarization independent band-pass filter consisting of polarization beam splitter and polarization rotation Bragg diffraction was experimentally demonstrated.

Silicon waveguide polarization rotation Bragg grating with phase shift section and sampled grating scheme

We describe a Bragg grating with a phase shift section and a sampled grating scheme that converts input polarization to orthogonal polarization. A very narrow polarization-independent wavelength peak can be generated by phase shift structures and polarization-independent multiple diffraction peaks by sampled gratings. The characteristics of the device were examined by transfer matrix and finite-difference time-domain methods.

Demonstration of 25-Gbps optical data links on silicon optical interposer using FPGA transceiver

We demonstrated a 25-Gbps error-free data link on a silicon optical interposer. The experimental results verified that our interposer is compatible with high-performance FPGAs, and transmitter pre-emphasis and receiver equalization reduced bit error rate of the optical data link.

Broadband and Polarization-Independent Efficient Vertical Optical Coupling With 45° Mirror for Optical I/O of Si Photonics *

Efficient, broadband, and polarization-independent optical input/output (I/O) coupling of silicon photonics chips is significant for its practical application, and single-mode vertical optical I/O coupling will be necessary for high-density optical I/O connections required in future high-performance computing systems. We demonstrated such optical coupling using a 45° mirror, which was integrated by a cost-effective dicing technique with a polishing process. The 45° mirrors were integrated into Si-rich silica (SiOx) waveguides on a Si substrate. To evaluate the light beam profile, which was important factor for the single-mode optical coupling, we measured near field patterns and far field patterns of light beams reflected by the 45° mirror. Owing to the polishing process, high-quality single-mode beams were successfully obtained as the vertical optical output. Using the fabricated 45° mirrors, the efficient single-mode vertical optical coupling with loss penalty of around 0.3 dB was demonstrated. The wavelength-dependent loss was less than 0.6 and 0.2 dB for TE and TM polarization, respectively. The polarization-dependent loss was also very small and it was less than 0.2 dB in 1500-1600 nm.

Silicon waveguide polarization rotation Bragg grating with resonator cavity section

Bragg grating with resonator cavity that converts the input polarization to orthogonal polarization is reported. The device works similar to a Fabry–Perot or ring resonators and very narrow polarization independent wavelength peak can be generated. The transfer matrix methods are used to examine the device characteristics. A 0.2-nm-wide polarization independent transmission wavelength peak was obtained by experiment. We also show theoretically using finite-difference-time-domain method that a flat-top response can be obtained by a two cavity structure.

Silicon waveguide polarization rotation Bragg grating with chirp, phase shift section or super-structure grating scheme

We describe a Bragg grating with phase shift section, chirp or super-structure grating scheme that converts the input polarization to orthogonal polarization. A very narrow polarization independent wavelength peak can be generated by phase shift structures and multiple diffraction peaks by sampled or super-structure gratings. Polarization independent flat-top response was obtained experimentally by chirped grating.

First demonstration of athermal silicon optical interposers with quantum dot lasers operating up to 125 °C

We demonstrated athermal silicon optical interposers integrated with quantum dot lasers at 1.3 μm, achieving a bandwidth density of 15 Tbps/cm2 with a channel line rate of 12.5 Gbps operating up to 125 °C without any bias adjustment.

Silicon waveguide polarization rotator sampled Bragg grating

In this Letter, we demonstrate, to the best of our knowledge, the first experimental results of sampled Bragg grating with polarization rotator function. Silicon waveguide is used. Multiple polarization-independent reflection wavelength peaks were obtained.

Silicon wire waveguide TE 0 /TE 1 mode conversion Bragg grating with resonant cavity section

Silicon wire waveguide TE0/TE1 mode conversion Bragg grating can be used in wavelength add/drop and polarization rotation Bragg diffraction. The device can implement many filtering functionalities required in wavelength division multiplexing optical communications. In this paper we describe TE0/TE1 mode conversion Bragg grating device incorporating resonant cavity section to obtain narrow transmission wavelength peak. Theoretical calculation agreed with measured wavelength response.

Mirror-based polarization-insensitive broadband vertical optical coupling for Si waveguide

To achieve an efficient, broadband, and polarization-insensitive vertical optical input/output for Si photonics, we demonstrated vertical optical coupling for a Si photonic wire waveguide with an integrated 45° mirror and a spot size converter. The output beam from the fabricated mirror was evaluated and a high-quality single mode beam was obtained. On the basis of coupling loss measurements, the coupling losses for the Si photonic wire waveguide were estimated to be 0.85 and 0.55 dB in TE and TM polarizations, respectively. The wavelength-dependent loss was ±0.1 dB over a wavelength range of 1500–1600 nm.