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Carrier suppressed parametric pump for Flat Gain Raman Parametric Cascade amplifier in Dense Wave Multiplexed systems



  1. Department of Electronics & Communication Engg., TIET (Deemed University), Patiala, India


We demonstrate improved performance of Raman parametric hybrid amplifier for L-band amplification in Dense Wave division Multiplexed (DWDM) systems using novel parametric pump modulation. Results have been evaluated in 16 × 10 Gbps using CSRZ (Carrier suppressed Return to Zero) modulation of parametric pump in terms of gain flatness, OSNR (Optical Signal to noise ratio), Bit Error Ratio (BER), eye diagrams and Q factor. Gain ripple is improved by nearly 11 dB while OSNR has improved by 2.5 dB. Q-factor at high parametric pump powers increases by factor of 1.33 resulting in significant BER improvement when using CSRZ modulated FOPA pump. Hybrid modulation of parametric pump has been proposed to suppress the high power idlers by controlling the shape of the pump signal using hybrid modules. Due to Four Wave Mixing (FWM) the parametric gain falls near the pump vicinity. Higher the pump power more severe is the fall in the gain. This sudden fall of gain around pump region defeats the use of parametric amplifier for flat gain. Though Ramanparametric hybrid is able to improve the gain flatness by tuning Raman amplifiers in the region of parametric gain fall but gain ripple is still significant. So we propose a CSRZ modulation of the parametric pump which helps achieve a peak gain of 40.45 dB with maximum gain ripple of 2.63 dB. The peak to peak gain variation of less than 1.2 dB has been achieved using CSRZ modulated parametric pump. Due to phase dependence of FWM, phase modulated pump show much better results confirming effective suppressing of FWM generated idlers using pump modulation. The variation of proposed system parameters with increase in data rate, change is parametric pump phase and with Raman pump frequencies and power have also been analyzed.


Raman-FOPA, Flat gain, CSRZ, Pump modulation.


GAGANPREET KAUR, Carrier suppressed parametric pump for Flat Gain Raman Parametric Cascade amplifier in Dense Wave Multiplexed systems, Optoelectronics and Advanced Materials - Rapid Communications, 17, 1-2, January-February 2023, pp.28-37 (2023).

Submitted at: June 20, 2022

Accepted at: Feb. 6, 2023