Yasuhiko Nakanishi

60 km, 256-split Optically-amplified PON Repeatered Transmission using 1.24 Gbit/s Upstream and 2.5 Gbit/s Downstream PON system

We successfully demonstrate a 60 km optically-amplified PON repeatered transmission experiment using commercial 1.24 Gbit/s upstream and 2.5 Gbit/s downstream PON systems with an optical-amplifier-based PON repeater, a burst-mode upstream pre-amplifier, and a combination of 4x and 64x splitters.

56-Gbaud 4-PAM (112-Gbit/s) operation of flip-chip interconnection lumped-electrode EADFB laser module for equalizer-free transmission

We fabricated a lumped-electrode type EADFB laser module using a flip-chip interconnection technique which provides a large modulation bandwidth. We obtained clear 56-Gbaud 4-PAM signal after 10-km SMF transmission with no equalizer using this module.

Heterogeneously Integrated PLC With Low-Loss Spot-Size Converter and Newly Developed Waveplate PBS for DC-DP-16QAM Receiver

Digital coherent transmission systems with multilevel and multicarrier modulation formats have been moving beyond 100-G systems. In this paper, we report a one-chip 400-G coherent receiver founded on a silica-based planar lightwave circuit (PLC) integration platform. To integrate a polarization beam splitter (PBS), two polarization rotators, four-optical hybrids, and 16 high-speed photodiodes (PDs) in one chip, we employed a 5%-Δ waveguide with a minimum bending radius of 300 μm, and the heterogeneous integration of InP-PDs. To achieve a compact receiver without any degradation in optical passive performance, we also investigated a three-branched spot size converter with a low loss and a high-fabrication tolerance and a waveplate type PBS with a high-polarization extinction ratio. Using these techniques, we fabricated a dual-carrier dual-polarization (DP) 16-level quadrature amplitude modulation (QAM) receiver PLC, and successfully demonstrated 32-Gbaud DP-16QAM signal demodulation for each channel.

Planar n-SI-n heterostructure athermal InP (110) optical modulator

We report an athermal InP (110) optical modulator with a simple planar n-SI-n heterostructure. A symmetrical push-pull operation provides a high-extinction ratio of >25 dB over the entire C-band and zero-chirp modulation. A Mach-Zehnder optical modulator (MZM) exhibits a 3 dB-EO bandwidth of 30 GHz and 40-Gb/s NRZ high-speed modulation with wavelength and temperature insensitive operation. We also successfully demonstrate an MZM integrated twin-IQ modulator that exhibits 56-Gb/s × 2 athermal QPSK modulation at constant drive and bias voltages.

Compact 100Gb/s DP-QPSK integrated receiver module employing three-dimensional assembly technology

We demonstrate a compact 100 Gbit/s DP-QPSK receiver module that is only 18 mm (W) x 16 mm (D) x 2.8 mm (H). The module size is reduced by using a ball grid array (BGA) package with three-dimensional assembly technology and by applying a heterogeneous integrated PLC. Error-free DP-QPSK signal demodulation is successfully demonstrated.

214-Gb/s 4-PAM Operation of Flip-Chip Interconnection EADFB Laser Module

We fabricated a Hi-FIT LE-EADFB laser module. Hi-FIT, which is a wire-free interconnection technique, provides a higher modulation bandwidth and a flatter frequency response than a conventional wire interconnection technique. The fabricated module has a 3-dB bandwidth of about 59 GHz and a sufficiently flat frequency response of less than 45 GHz. Using this module, we demonstrated a single-wavelength single-polarization direct-detection 4-PAM transmission with a record net data rate of 200 Gb/s. And with 4-PAM operation at 214 Gb/s, we obtained a BER of less than 3.8 × 10–3, which is an error-free condition using a 7%-OH HD-FEC code, even after a 10-km SMF transmission.

4 × 28 Gbaud PAM4 integrated ROSA with high-sensitivity APD

We demonstrate the first 4 × 28 Gbaud PAM4 data reception with an integrated APD-ROSA. A minimum receiver sensitivity of ™21.2dBm OMA of the inner-eye was obtained, which enable us to achieve 30-km transmission, assuming a SSMF.

Flip-chip interconnection EA-DFB laser module for 100-Gbit/s/λ application

We have developed a flip-chip interconnection technique to solve the problem of the degradation of the modulation bandwidth of an optical transmitter due to the parasitic inductance of bonding wire. And we have fabricated an LE-EA-DFB laser module that has a 3-dB bandwidth of 59 GHz thanks to our flip-chip interconnection technique. The fabricated optical receiver, which includes a wideband electrical amplifier, has a 3-dB bandwidth of 51 GHz. Using these optical modules with a 3-dB bandwidth of more than 50 GHz, we have obtained a bit-error rate of less than 2 × 10-4, which is an error-free condition using KP4 forward error correction, under 53.2-Gbaud 4-level pulse amplitude modulation (4-PAM) operation without an equalizer even after a 2-km transmission through single-mode fiber.

High-linearity avalanche photodiode for 40-km transmission with 28-Gbaud PAM4

We present a high-linearity avalanche photodiode (APD) for 28-Gbaud PAM4, namely. 56 Gbit/s/λ,. With an optical receiver incorporating the APD, a 40-km transmission with -17 dBm receiver sensitivity was successfully demonstrated for the first time.

Compact 8-wavelength receiver optical sub-assembly with a low-loss AWG demultiplexer for 400-gigabit datacom

A compact receiver optical sub-assembly (ROSA) for 8-wavelength 400-gigabit links was developed. Wavelength scalability of the ROSA with high responsivity of 0.7 A/W was achieved with a low-loss multimode-output arrayed waveguide grating.