A NOVEL DESIGN OF DISPERSION COMPENSATING RAMAN/TWO STAGE EDFA HYBRID FOR AMPLIFICATION IN L-BAND AND U-BAND

摘要

Dispersion compensating discrete Raman amplifier are known to open up new wavelength bands. However there is also the issue of wastage of Raman pump power. The length of dispersion compensating discrete Raman amplifier is decided to minimize the dispersion. Hence significant pump power is wasted. In this paper, a novel design of dispersion compensating Raman/Two stage EDFA hybrid is reported which recycles the residual pump power from the dispersion compensating Raman and feeds this pump to the second stage of two stage EDFA. The first stage is remotely pumped from another laser source. Using this configuration, we have achieved an extremely large gain bandwidth of 117.5nm from 1582.5-1700nm with a 3dB ripple, has been achieved This amplifier topology while using minimum no of pump sources solves the twin problem of wastage of Raman pump power and providing amplification in U-band. We also performed the simulations of another topology in which a 5m long unpumped EDF was inserted between the first stage and second stage of the EDFA. The backward traveling Amplified Spontaneous Emission (ASE) from the second stage caused the pumping in the unpumped EDF thereby causing signal gain instead of loss. This topology further showed an enhancement in gain of 1-2 dB in the wavelength band of interest (1600-1700nm). The design issue in these topologies is the length of the EDF's. By suitably modeling these lengths, we can obtain appropriate gain profile.