Absolute frequency references at 1529 nm and 1560 nm using modulation transfer spectroscopy

TL;DR

This paper presents a dual optical frequency reference at 1529 nm and 1560 nm using modulation transfer spectroscopy on rubidium transitions, achieving high stability and an estimated 1 kHz accuracy for telecom applications.

Contribution

The work introduces a novel dual-frequency reference system based on rubidium modulation transfer spectroscopy for the telecom C-band, with detailed analysis of stability and accuracy.

Findings

Achieved a stable frequency reference at 1529 nm and 1560 nm.

Estimated an absolute accuracy of approximately 1 kHz.

Analyzed effects of power, magnetic field, and gas collisions on stability.

Abstract

We demonstrate a double optical frequency reference (1529 nm and 1560 nm) for the telecom C-band using $^{87}$Rb modulation transfer spectroscopy. The two reference frequencies are defined by the 5S$_{1/2} F=2 \rightarrow $ 5P$_{3/2} F'=3$ two-level and 5S$_{1/2} F=2 \rightarrow $ 5P$_{3/2} F'=3 \rightarrow $ 4D$_{5/2} F"=4$ ladder transitions. We examine the sensitivity of the frequency stabilization to probe power and magnetic field fluctuations, calculate its frequency shift due to residual amplitude modulation, and estimate its shift due to gas collisions. The short-term Allan deviation was estimated from the error signal slope for the two transitions. Our scheme provides a simple and high performing system for references at these important wavelengths. We estimate an absolute accuracy of $\sim$ 1 kHz is realistic.