Open AccessEnhanced nonlinear spectral broadening and sub-picosecond pulse generation by adaptive spectral phase optimization of electro-optic frequency combs
Author(s) -
B. S. Vikram,
Roopa Prakash,
Shankar Kumar Selvaraja,
V. R. Supradeepa
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.387153
Subject(s) - doppler broadening , optics , frequency comb , picosecond , brillouin scattering , materials science , bandwidth (computing) , self phase modulation , spectral width , nonlinear optics , optical fiber , physics , laser , spectral line , telecommunications , computer science , astronomy
We utilize adaptive optimization to enhance the spectral broadening of an amplified electro-optic frequency comb with a 25 GHz repetition rate in a highly nonlinear fiber and subsequently generate sub-picosecond pulses. The spectral phase of the comb is adaptively optimized by a Fourier pulse shaper in a closed control loop with the HNLF output spectrum as the process variable to be optimized. Enhanced spectral broadening also increases the stimulated Brillouin scattering threshold allowing increased power scaling and thereby boosting the bandwidth by a factor of more than 13 times over the initial comb. System versatility to varying conditions is demonstrated by achieving consistent bandwidth enhancement (nearly or more than 100 lines) in varying operating conditions that distort the temporal profile of the comb. In all cases, the optimization yields a near transform limited pulse that enters the nonlinear fiber. Sub-picosecond pulse generation is achieved with a short length of single mode fiber post the nonlinear fiber.