Speaker
Description
Optical frequency combs generated through cascaded four-wave mixing offer a flexible route to broadband sources with widely-spaced spectral lines. Their spectral profile depends strongly on phase matching, motivating approaches that extend dispersion control beyond fixed waveguide designs. This presentation traces the development of programmable dispersion as a tool for controlling nonlinear frequency generation, from our first demonstration of controllable phase matching to automated optimization of comb bandwidth.
Our approach combines a custom-built dual-oscillator power amplifier, a spatial light modulator-based dispersion controller, and highly nonlinear fiber (HNLF). Applying a programmable spectral phase profile to an initial seed comb entering the HNLF controls subsequent cascaded four-wave mixing. We first demonstrate that tuning group delay dispersion and fourth-order dispersion provides direct control over the mixing process, achieving more than threefold bandwidth tuning with the broadest spectrum containing 52 comb lines spanning 175 nm around 1550 nm.
Building on this concept, we introduce genetic optimization to explore a broader dispersion parameter space and select phase profiles that produce desired spectral bandwidths. The controller manipulates dispersion terms through fifth order across 11 initial comb lines. Experimental feedback evaluates successive profiles using fitness functions favoring spectral expansion or contraction, enabling automated control of nonlinear evolution. The algorithm generates controllable comb spectra from as few as 10 lines to as many as 167 lines, with a line spacing of 404 GHz (~3.2nm at 1550 nm), with all spectra at 120 mW average power. Comb bandwidths range from 29 nm to more than 530 nm, providing over eighteenfold variation in spectral coverage.
Together, these demonstrations establish a progression from programmable control of phase matching to adaptive optimization of nonlinear spectral generation. We discuss the underlying physics, experimental implementation, and opportunities for reconfigurable comb sources with selectable bandwidths, highlighting how programmable optics and feedback expand control over nonlinear interactions.
| I am the presenting author | No |
|---|---|
| If you are not the presenting author, please give the presenting author's name: | Darren D. Hudson |