Improved noise rejection mechanism for optical frequency comb designed at 94 GHz window spectrum

Abstract

In this present work, novel mechanisms are described to reduce the noise in optical frequency comb through subsequent optical and electrical mixing and amplification techniques, which provides almost sinusoidal response in electrical domain and negligible ripple when the entire spectrum is viewed. The combination that we have used here consists of an optical Bessel filter centred at 1,310 nm, the laser frequency having linewidth of 10 GHz, followed by an optical amplifier (OA) with gain of about 10-12 dB and the output is fed through electrical Bessel broadband filter which is tapped at all the tuning frequencies spaced at 1 GHz. Results show that all the output spectrum and signals are stable with very low noise at all the frequencies at which it was tuned. The novel processing technique was the most important requirement in order to separate the spectrum lines, make them amplified, cause least interference between them, and make the output as noiseless and as stable as possible.