CMOS Saturation Spectrometer With a Miniaturized Fabry–Pérot Cavity for the Lamb-Dip Interrogation of OCS Molecules to Enhance the Q of CSMC

CMOS Saturation Spectrometer With a Miniaturized Fabry–Pérot Cavity for the Lamb-Dip Interrogation of OCS Molecules to Enhance the Q of CSMC

clockVolume: 73, Issue: 10, October 2025

authorFang Shen

CMOS Saturation Spectrometer With a Miniaturized Fabry–Pérot Cavity for the Lamb-Dip Interrogation of OCS Molecules to Enhance the Q of CSMC

Abstract
DOI: 10.1109/TMTT.2025.3577939   IEEEXplore: https://ieeexplore.ieee.org/document/11044868
Device
Saturation spectrometer in 65-nm CMOS technology integrated with a miniaturized Fabry-Pérot (FP) cavity to enhance the Q of the chip-scale molecular clock (CSMC)
Spectrum
216-233 GHz
Novelty
The compact FP cavity features pinhole coupling, 0.36 cm3 volume, with a measured cavity Q of 1.9x104. By selectively burning out OCS molecules under pressure in the cavity, sufficiently strong EM fields are produced and a significant sub-Doppler Lamb-dip spectral line Q enhancement is realized.
Application
Highly stable miniaturized clocks for wireless access networks, to position and navigate robots and drones, for array sensing, seismography and coherent netted radar.
Performance
Spectral line Q of 8.9x105 with zero-velocity OCS molecules at 2.5 Pa pressure in the FP cavity and an analog instrument receiver for a 2.9x Q enhancement of the unsaturated case; Q of 3.55 x105 with OCS molecules at 7.5 Pa pressure in the FP cavity and a heterodyne CMOS receiver for a spectral line 2.1x Q enhancement of the unsaturated case. 263 fW/Hz0.5 RX noise equivalent power (NEP), 42 dB SNR for the chip case.