Yoshihiro Emori

100 nm bandwidth flat gain Raman amplifiers pumped and gain-equalized by 12-wavelength-channel WDM high power laser diodes

We demonstrate 100 nm bandwidth Raman amplifiers using 12-wavelength-channel WDM pump laser diode unit. The gain flatness is less than /spl plusmn/0.5 dB, which is achieved through an asymmetric channel allocation of pump and without any gain equalization filters.

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.

Gain and noise tilt control in multi-wavelength bi-directionally pumped Raman amplifier

We proposed an optimized bi-directional pumping scheme that realized a good flatness of Raman gain and variety of optical noise figure spectra, simultaneously. We used previously developed low-noise pump lasers for forward-pumping. By means of the proposed scheme comprising five pump wavelengths, about 2.3 dB variation of wavelength dependence of noise figure are demonstrated at a fixed flat Raman gain of 9 dB for 76 km of single mode fibre.

Recent advances in ultra-wideband Raman amplifiers

This talk will review fundamentals of ultra-wideband Raman amplifiers, recent progress of high power pump lasers, and system applications of Raman amplifiers. Pump wavelength determines the gain spectrum of a Raman amplifier. This implies that the gain created by a multi wavelength pumping can have a wideband gain profile, which is approximately described by a linear superposition of each gain by individual pumping, Therefore, in order to realize wideband Raman amplifiers, pump lasers with optimally different wavelengths have to be multiplexed efficiently.

Simple gain control method for broadband Raman amplifiers gain-flattened by multi-wavelength pumping

We propose and experimentally demonstrate that, for broadband Raman amplifiers with five wavelength pump channels, gain flatness can be preserved at different gain levels by means of changing only two parameters to control the launched pump power.

High-power Cascaded Raman Fiber Laser with 41-W output power at 1480-nm band

A cascaded Raman laser with 41-W CW output at 1480-nm band was demonstrated by a 65-m silica-based highly nonlinear fiber as the Raman gain medium.

Broadband flat-noise Raman amplifier using low-noise bidirectionally pumping sources

We propose and experimentally demonstrate an optimised bidirectional pumping scheme that realizes a less than 0.7 dB flatness over C- and L-bands for both Raman gain and optical noise figure, simultaneously. In order to use forward-pumping for the proposed method, a new type of pump laser having low relative intensity noise is also developed.

State of the art in diode pumped Raman amplifiers

Recent development on diode pumped Raman amplifiers are reviewed. Design issues of multi-wavelength pumping scheme, which enables to obtain a broadband, flat and high gain by using diode lasers, are presented with simulation and experimental results. Polarization dependence of Raman gain, which is caused by a linearly polarized pump such as a diode laser, is also discussed.

Polarization insensitive broadband transparent DCF module with faraday rotator mirror, Raman-amplified by single polarization diode-laser pumping

A DCF module Raman-amplified by single polarization diode-laser pumping was fabricated. The DCF compensates both dispersion and dispersion slope of 40-km SMF without loss increase from 1530 nm to 1620 nm. The PMD and PDG were 0.01 ps and <0.01 dB, respectively.

Pump Laser Diodes and WDM Pumping

This chapter discusses issues surrounding the pump laser diodes for broadband Raman amplifiers, which range from fundamentals to industry practices of Raman pump sources based on the so-called 14XX nm pump laser diodes. It also refers to design issues of wavelength-division-multiplexed (WDM) pumping for realizing a broad and flat Raman gain spectrum over the signal band. Section 5.1 introduces fundamentals of pump laser diodes. Section 5.2 refers to the principle and design issues of WDM pumping technique. Section 5.3 discusses details of pump laser diodes and their efficiently combining and depolarizing technologies. Section 5.4 describes practical Raman pump units. And Section 5.5 briefly touches upon ongoing issues on copumped Raman amplifiers and their pumping sources.