# Low-Noise Millimeter-Wave Down-Conversion Technology for Chip-Scaled Optical Clocks

## TL;DR

This paper presents a low-noise system to convert high-frequency millimeter-wave signals to lower frequencies for use in compact optical clocks.

## Contribution

A novel low-phase-noise down-conversion system for millimeter-wave signals in chip-scaled optical clocks is developed and characterized.

## Key findings

- The system down-converts 100 GHz to 100 MHz and 10 MHz with phase noise of −117 dBc/Hz and −124 dBc/Hz at 100 Hz, respectively.
- Frequency stability reaches 5.0 × 10−15 at 1 s for the 100 MHz signal and 5.7 × 10−14 at 1 s for the 10 MHz signal.
- The system's stability improves to 10−16 level at 10,000 s for both frequencies.

## Abstract

This article reports on a millimeter-wave (MM-wave) signal down-conversion system with low phase noise for chip-scaled optical clocks. The system utilizes analog regenerative frequency division, low-noise fractional frequency division, and phase-locked frequency division techniques to down-convert a 100 GHz MM-wave signal to 100 MHz with phase noise of −117 dBc/Hz @100 Hz, −133 dBc/Hz @1 kHz, and 10 MHz with phase noise of −124 dBc/Hz @100 Hz and −143 dBc/Hz @1 kHz. The frequency stability of the signal down-converted to 100 MHz is 5.0 × 10−15 @ 1 s and 1.8 × 10−16 @ 1000 s, while the frequency stability of the 10 MHz signal is 5.7 × 10−14 @ 1 s and 5.9 × 10−16 @1000 s, both of which decrease to the 10−16 level at 10,000 s. This down-conversion system meets the frequency conversion requirements of state-of-the-art chip-based optical clocks and micro-cavity optical combs.