Yasuaki Hashizume

Ultralow Power Consumption Silica-Based PLC-VOA/Switches

We have achieved a silica-based PLC thermooptic switch with a power consumption of only 30 mW without any deterioration in the optical properties by using a tapered narrow ridge structure. To reduce the power consumption further, we propose a novel structure, the suspended narrow ridge structure, which has the advantages of both the tapered narrow ridge structure and the already reported suspended-bridge structure. As a result, we achieved PLC-VOA/switches with excellent heat design flexibility and a power consumption of 20 mW. In addition, using the proposed the suspended narrow ridge structure, we demonstrate a 16-channel V-AWG with a compact size of 20 times 17 mm and a low total power consumption of 320 mW.

Planar lightwave circuit polarization mode dispersion compensator

We fabricated an integrated-type optical PMD compensator on a silica-based planar lightwave circuit, where an endless polarization controller and a polarization-dependent delay line are installed. We confirmed its operational principle in a 43-Gbps transmission system.In this letter, we fabricated an integrated polarization-mode dispersion compensator on a silica-based planar lightwave circuit that incorporated an endless polarization controller and a fixed polarization dependent delay line. The compensator consisted of polarization beam splitters, thermooptic phase shifters, tunable couplers, and polarization converters. We experimentally confirmed its operation at a data rate of 43 Gb/s.

Linear optical IQ modulator for high-order multilevel coherent transmission

We devised an optical modulator with a high field-response linearity, which is suitable for a DAC-based multilevel coherent transmitter. An advantage over a conventional MZM in terms of the linearity-loss tradeoff was demonstrated.

Novel birefringence compensating AWG design

We propose a novel birefringence compensating arrayed waveguide grating (AWG) design that utilizes birefringence dependence on core width. We successfully demonstrated a polarization insensitive 100 GHz-spaced 16-channel multiplexer with a polarization dependent wavelength shift of 0.01 nm.

Planar lightwave circuit polarization-mode dispersion compensator

In this letter, we fabricated an integrated polarization-mode dispersion compensator on a silica-based planar lightwave circuit that incorporated an endless polarization controller and a fixed polarization dependent delay line. The compensator consisted of polarization beam splitters, thermooptic phase shifters, tunable couplers, and polarization converters. We experimentally confirmed its operation at a data rate of 43 Gb/s.

Influence of Intrachannel Crosstalk With Frequency Dependence on Signal Degradation in Optical Switch Network

In this paper, we show the influence of intrachannel crosstalk in an optical switch network. The intrachannel crosstalk is mainly due to a signal that is not sufficiently blocked by the optical switch. The signal has a broadband spectrum and causes coherent crosstalk at the optical switching node. We investigate analytically the relationship between the channel isolation of the optical switching node that the optical switch network comprises and the crosstalk penalty due to the broadband signal. We confirm experimentally that the relationship is suited to the optical switch network that emulates an optical cross-connect system. We also show experimentally that it is important to use the optical switch with a high channel isolation level in the entire range of the signal bandwidth in order to suppress the impairment due to the crosstalk. We confirm that in a 50-GHz spaced system, a 44-Gb/s return-to-zero differential quadrature phase-shift-keying signal is sufficiently transmitted without a crosstalk penalty through 24 optical switching nodes, comprising wavelength selective filters with a high channel isolation level in the entire range of the signal bandwidth.

Integrated-optic OFDM demultiplexer using multi-mode interference coupler-based optical DFT circuit

We report a silica-PLC OFDM demultiplexer comprising an N × N multi-mode interference coupler-based DFT circuit. The demultiplexer, which can demultiplex four OFDM sub-carriers simultaneously, is realized and applied to 4 × 10-Gbit/s signal demultiplexing.

Packaging Technology for Ultra-Small Variable Optical Attenuator Multiplexer (V-AWG) With Multichip PLC Integration Structure Using Chip-Scale-Package PD Array

We have developed an ultra-small 16-channel variable optical attenuator (VOA) multiplexer (V-AWG) with excellent optical performance by using multichip planar lightwave circuit (PLC) integration technology. The insertion loss is 3.2 dB, and the polarization-dependent loss (PDL) at 25 dB attenuation is less than 0.3 dB. The module size is 90 mmtimes55 mmtimes14 mm. We describe our concept and developed techniques as regards to the design, fabrication, and packaging of the module, focusing particularly on a chip-scale-packaged monitor photodiode array (CSP-PD) that we developed as a key component of our technique

In-band OSNR monitor with high-speed integrated Stokes polarimeter for polarization division multiplexed signal.

An in-band optical signal-to-noise ratio (OSNR) monitor is proposed, based on an instantaneous polarization state distribution analysis. The proposed monitor is simple, and is applicable to polarization division multiplexed signals. We fabricate a high-speed Stokes polarimeter that integrates a planar lightwave circuit (PLC) based polarization filter, high-speed InP/InGaAs photodiodes and InP hetero-junction bipolar transistor (HBT) trans-impedance amplifiers (TIA). We carry out proof-of-concept experiments with the fabricated polarimeter, and successfully measure the OSNR dependent polarization distribution with 100-Gb/s dual polarization quadrature phase shift keying (DP-QPSK) signals.

40Gbit/s-class-λ-tunable WDM/TDM-PON using λ-selectable B-Tx and 4 x M cyclic AWG router for flexible photonic aggregation networks

This paper proposes a 40Gbit/s-class-λ-tunable WDM/TDM-PON for flexible photonic aggregation networks that achieves the aggregation of a large number of users using the DWBA algorithm without an L2-SW. It also clarifies the scalability of the proposed system in terms of the transmission distance and the number of users. A λ-switching transmission experiment was conducted using a newly developed 10Gbit/s x 4λ selectable B-Tx and 4 x 4 cyclic AWG router.