Hiroyuki Matsuura

First demonstration of ultra-low-energy hierarchical multi-granular optical path network dynamically controlled through NSI-CS for video related applications

We developed ODU-XC, CDC-ROADM, and silicon photonics switch, and built an eight-node network capable of 90Tbps based on NSI-CS standard protocol. Its energy consumption was orders of magnitude lower than that achievable with IP routers.

Broadband silicon photonics 8 × 8 switch based on double-Mach–Zehnder element switches

We fabricated and characterized a silicon photonics 8 × 8 strictly non-blocking optical switch based on double-Mach-Zehnder (MZ) element switches. The double-MZ switches, each of which consisted of an intersection and two asymmetric MZ switches, enabled the suppression of crosstalk across a wide wavelength range. The 8 × 8 switch exhibited an average fiber-to-fiber insertion loss of 11.2 dB and -20 dB crosstalk in a bandwidth wider than 30 nm. Furthermore, we constructed an 8 × 8 polarization-diversity switch by using two 8 × 8 switches and demonstrated 32-Gbaud dual-polarization, quadrature-phase-shift-keying, four-channel wavelength-division-multiplexed signal transmission without significant signal degradation.

Sub-millisecond timing-jitter-free tuning of parametric dispersion compensator.

We demonstrate sub-millisecond tuning of a prototype parametric tunable dispersion compensator (P-TDC) based on cascaded polarization-diverse four-wave mixing (FWM) process with a fast tunable and highly wavelength-stable pump light source. The pump light source is developed using a tunable distributed amplification chirped sampled grating distributed reflector laser that is fully wavelength tunable by on-chip heaters with a 3-dB frequency response of 45 kHz, resulting in fast dispersion tuning of less than 50 μs without additional timing jitter. The P-TDC is developed as the first prototype to satisfy essential requirements for practical network uses: stable input-polarization diversity, input-wavelength preservation, and seamless dispersion tunability for entire C-band input wavelengths are simultaneously achieved.

Dynamic parametric dispersion compensation using FPGA pump controller and dispersion monitor

We demonstrate an autonomous fast parametric dispersion compensator with a fast TDA-CSG-DR laser and a dispersion monitor based on spectral shearing interferometer. A response time of less than 17 ms, potentially sub millisecond, is achieved.

Multi-port optical switch based on silicon photonics

We review research progress on multiport optical switches based on silicon photonics, with a primary focus on our own 8×8, 32×32 PILOSS switches, polarization insensitivity and integration with electronics. Challenges and future prospects are discussed.

Demonstration of 720×720 optical fast circuit switch for intra-datacenter networks

Intra-datacenter traffic is growing more than 20% a year. In typical datacenters, many racks/pods including servers are interconnected via multi-tier electrical switches. The electrical switches necessitate power-consuming optical-to- electrical (OE) and electrical-to-optical (EO) conversion, the power consumption of which increases with traffic. To overcome this problem, optical switches that eliminate costly OE and EO conversion and enable low power consumption switching are being investigated. There are two major requirements for the optical switch. First, it must have a high port count to construct reduced tier intra-datacenter networks. Second, switching speed must be short enough that most of the traffic load can be offloaded from electrical switches. Among various optical switches, we focus on those based on arrayed-waveguide gratings (AWGs), since the AWG is a passive device with minimal power consumption. We previously proposed a high-port-count optical switch architecture that utilizes tunable lasers, route-and-combine switches, and wavelength-routing switches comprised of couplers, erbium-doped fiber amplifiers (EDFAs), and AWGs. We employed conventional external cavity lasers whose wavelength-tuning speed was slower than 100 ms. In this paper, we demonstrate a large-scale optical switch that offers fast wavelength routing. We construct a 720×720 optical switch using recently developed lasers whose wavelength-tuning period is below 460 μs. We evaluate the switching time via bit-error-ratio measurements and achieve 470-μs switching time (includes 10-μs guard time to handle EDFA surge). To best of our knowledge, this is the first demonstration of such a large-scale optical switch with practical switching time.

High-power and narrow-linewidth tunable distributed-reflector laser

Deployment of digital coherent transmission technologies to metro networks drives the use of higher-order modulation formats such as PDM-16QAM and downsizing of optical transceivers. A narrow-linewidth (<300 kHz) tunable laser with high output power (>+17 dBm) is very attractive for such purposes, not only because it can compensate for the modulation loss increase caused by a high-peak-to-average ratio of the electrical driving signal of higher-order modulation formats, but also because it can be shared between transmitter and receiver saving the foot-print and power dissipation. This paper reviews the Tunable Distributed Amplification — Chirped Sampled Grating — Distributed Reflector (TDA-CSG-DR) laser being developed for metro application.

Autonomous Parametric Tunable Dispersion Compensation for Dynamic Optical Switching

We demonstrate dynamic parametric optical dispersion compensation in dynamic optical path networks (DOPNs). A fully automatic parametric tunable dispersion compensator (P-TDC) based on four-wave mixing process is developed with a fast tunable distributed amplification chirped sampled grating distributed reflector laser, a field-programmable gate array (FPGA) pump controller, and a fast dispersion monitor based on spectral shearing interferometer. The dispersion monitor detects a change in the dispersion of a path, and the monitoring signal is fed forward to the FPGA controller. The fast tunable laser sets its wavelength accordingly for the dispersion compensation through parametric process. A response time of <;17 ms is demonstrated in a testbed of DOPN. The autonomous P-TDC has a potential response of submillisecond.

Fast and accurate calibration method for large-port-count Si-wire PILOSS optical switch

We propose a calibration method for N×N Si-wire path-independent-insertion-loss (PILOSS) optical switches with thermo-optic Mach-Zehnder-interferometer (MZI) element switches. Calibration for a 32x32 switch is numerically demonstrated with an error less than 1% within an hour.

Ultralow-crosstalk and broadband multi-port optical switch using SiN/Si double-layer platform

We exploit a SiN/Si double-layer platform for an ultra-low crosstalk multi-port optical switch that exhibits −50 dB crosstalk in a bandwidth wider than the C-band. The platform possesses full compatibility with a silicon photonics platform.