Shunichi Matsushita

Cost-effective depolarized diode pump unit designed for C-band flat-gain Raman amplifiers to control EDFA gain profile

A cost-effective pumping unit with only two depolarized pump LDs for C-band flat-gain Raman amplifiers is proposed. The Raman gain in DCF is applied to simultaneously control the overall gain and gain flatness of an in-line EDFA.

Duration-tunable 100-GHz sub-picosecond soliton train generation through adiabatic Raman amplification in conjunction with soliton reshaping

We demonstrate generation of 100-GHz soliton train with tunability of temporal duration from 0.84 to 2.1 ps by adiabatic Raman amplification with soliton reshaping, while keeping near transform-limit, low pedestal level and low stimulated Brillouin scattering.

Low loss 1×93 wavelength selective switch using PLC-based spot size converter

A massive port count WSS using planar lightwave circuit as optical input/output ports is proposed. We demonstrate a 1×93 LCOS-based WSS with less than 9.0 dB insertion loss and typically 37.0 GHz 0.5 dB passband width.

Design of temperature insensitive depolarizer for Raman pump laser diode

We have presented about design of temperature insensitive depolarizer for Raman pump laser diode using optimization of the length of the output pigtail polarisation mode fibre (PMF) and the depolarizer. Then the temperature dependence of degree of polarisation (DOP) caused by the state of polarisation (SOP) fluctuation in front of depolarizer have been demonstrated through the simulation where the thermal expansion and the beat length variation of output PMF were included. We have obtained good agreement simulation and experimental results. Applying the simulation results on designing the depolarizer and the output PMF, we have successfully suppressed the variation of DOP and decreased the DOP value, less than 4%.

Efficiency of highly nonlinear fiber in soliton converter for 40 Gbit/s 10,000 km fiber transmission

We show that highly nonlinear fiber is essential to reduce the input power, length, loss, and noise of a soliton converter, and that it actually halves the input power and length compared with a conventional DSF in 40 Gbit/s 10,000 km transmission.

S-band CW lightwave generation using four-wave mixing in high-nonlinearity fiber

A multi-channel CW-WDM signal source in the S-band is presented using a 153 nm conversion bandwidth, the widest to our knowledge, providing four-wave mixing (FWM) in a high-nonlinearity fiber. Up to a 40 dB optical signal to noise ratio (OSNR) is realized by avoiding improper FWM.

Novel Automatic Service Restoration Technique by Using Self-Reconfiguration of Network Resources for a Disaster-struck Metro-Access Network

This paper shows the concept of the elastic lambda aggregation network (EλAN) that will achieve an elastic common access infrastructure for the metro-access network. It proposes a service restoration technique that uses optical path switching and intercentral office handover for EλAN to recover from disasters. The feasibility of the proposed service restoration technique is successfully demonstrated for the first time by using a prototype testbed of a metro-access network. By applying both orthogonal frequency division multiplexing and adaptive modulation, the system automatically changes the transmission parameters (modulation level, the number of subcarriers, and symbol rate) according to the service requirements and conditions of the optical distribution network, such as the links end-to-end optical loss, in order to achieve accommodate multiple services. In the experiment, an optical network unit in a faulted system automatically reconnected within 10 s to another office 20-km away with the same throughput.

Repetition-rate and wavelength tunable optical short pulse source by using comb-like profiled fiber compression and supercontinuum generation

A repetition-rate and wavelength tunable optical pulse source by using comb-like profiled fiber compression and supercontinuum generation has been developed. A supercontinuum with 70 nm bandwidth is observed for 500-1000 MHz repetition rate.

Ultra short pulse generation and reshaping using highly nonlinear fibers

We experimentally investigate the generation of a low-noise ultra short pulse train from 40GHz to160GHz by using Comb-like profiled fiber (CPF) for adiabatic soliton conversion and compression. Highly nonlinear fibers allow us to reduce total length of CPF as well as to utilize Kerr effect in the fiber effectively. We demonstrate generations of 160GHz soliton train of 750fs, the compression to 500fs of 40GHz externally-modulated pulse with wideband tunability over 30nm. Then we apply the CPF pulse compression technique to achieve the programmable repetition tunability from 5 to 500 MHz in low pedestral 300fs pulse train generation.