Resonant Electro-Optic Frequency Comb

TL;DR

This paper demonstrates a broadband electro-optic frequency comb using a whispering gallery mode resonator that operates at low power levels, offering a more efficient alternative to Kerr-based combs for high-speed optical communications.

Contribution

It introduces a novel electro-optic frequency comb in a high-Q resonator utilizing second-order non-linearity, achieving low-power operation and precise carrier spacing.

Findings

Operates at microwave powers three orders of magnitude lower than existing devices.

Uses second-order non-linearity for more efficient comb generation.

Potential for integration into next-generation long-distance telecommunication systems.

Abstract

High speed optical telecommunication is enabled by wavelength division multiplexing, whereby hundreds of individually stabilized lasers encode the information within a single mode optical fiber. In the seek for larger bandwidth the optical power sent into the fiber is limited by optical non-linearities within the fiber and energy consumption of the light sources starts to become a significant cost factor. Optical frequency combs have been suggested to remedy this problem by generating multiple laser lines within a monolithic device, their current stability and coherence lets them operate only in small parameter ranges. Here we show that a broadband frequency comb realized through the electro-optic effect within a high quality whispering gallery mode resonator can operate at low microwave and optical powers. Contrary to the usual third order Kerr non-linear optical frequency combs we rely on the second order non-linear effect which is much more efficient. Our result uses a fixed microwave signal which is mixed with an optical pump signal to generate a coherent frequency comb with a precisely determined carrier separation. The resonant enhancement enables us to operate with microwave powers three order magnitude smaller than in commercially available devices. We can expect the implementation into the next generation long distance telecommunication which relies on coherent emission and detection schemes to allow for operation with higher optical powers and at reduced cost.