Broadband Optoelectronic Mixer for Terahertz Frequency-Comb Measurements

Published

May 5, 2025

Author(s)

Jizhao Zang, Jesse Morgan, Andreas Beling, Scott Papp

Abstract

We demonstrate ultra-broadband optoelectronic mixing of frequency combs that provides phase-coherent detection of a repetition frequency up to 500 GHz, using a high-speed modified uni-traveling carrier (MUTC) photodiode. Nonlinear photo-electron effects in the photodiode itself enable harmonic generation and down-mixing process of combs with widely different repetition frequency. Specifically, we generate two, 25 GHz frequency combs and use an optical filter to explore coherent down-mixing to baseband of comb spectral components across microwave, millimeter wave, and THz frequencies. The exceptional noise performance of the optoelectronic mixer enables the phase-coherent measurement of millimeter and THz frequency combs with an Allan deviation of 10^-13/τ for a measurement time of τ. We further investigate the dependence of conversion loss on the reverse bias voltage and photocurrent. The experimental results indicate that we can minimize the conversion loss by operating the photodiode at an optimal voltage and maximum available photocurrent. Our work provides a solution for millimeter and THz frequency comb measurements and facilities fully stabilized frequency combs with microresonators.

Citation

Optics Letters

Volume

50

Pub Type

Journals

Download Paper

https://doi.org/10.1364/OL.557366

Local Download

Citation

Zang, J. , Morgan, J. , Beling, A. and Papp, S. (2025), Broadband Optoelectronic Mixer for Terahertz Frequency-Comb Measurements, Optics Letters, [online], https://doi.org/10.1364/OL.557366, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958964 (Accessed October 1, 2025)