Boulder Precision Electro-optics — Department of Defense SBIR Phase II: SB121-001

Description

A laser stabilized to a cryogenically-cooled silicon Fabry-Perot cavity will provide a factor of 1000 improved time base over a currently available maser, while suffering none of the ambient environmental perturbations.  A field-deployable device would revolutionize many physics experiments, paving the way for cutting-edge research. Frequency stabilized laser oscillators are critical tools in many cutting-edge experiments.  From tests of general relativity and variation of fundamental constants, to development of better quantum sensors, a laser locked to a high finesse Fabry-Perot cavity is a crucial part of many devices.  Improved performance from atomic clocks, including a reduction in size, weight, and power (SWaP) allows huge advances in many fields. Ultimately, cryogenic silicon cavity systems would be suited to replacing conventional hydrogen masers.  The short-term stability (sampling times of less than 10 seconds) of a cryogenic silicon laser would be a factor of 100 better than a maser.  Because of silicon’s low drift nature, it would continue to outperform a maser to long time scales.  The potential market for replacing masers is immense. Current generation Fabry-Perot cavities made from Ultra Low Expansion (ULE) glass suffer from an innate long-term drift due to a property of the material.  This change in optical laser frequency can limit the effectiveness of a cavity in the scenarios described above.  One method to improve a Fabry-Perot cavity-based laser oscillator is to use silicon as the cavity spacer material.  Silicon has a coefficient of zero expansion at 124 K, requiring cryogenic operation to reach the best performance possible.    D.G. Matei – 1.5 mm Lasers with Sub-10 mHz Linediwth (PRL 2017) B. Marechal – Development of a Cryogenic Silicon Cavity Stabilized Laser (IFCS 2018) C.T. Taylor – Measurement of the thermal expansion of an all-sapphire optical cavity (IEEE 1997) M. Notcutt – Cryogenic system for a sapphire Fabry-Perot optical frequency standard (Cryogenics 1996) C.T. Taylor – Cryogenic, all-sapphire, Fabry-Perot optical frequency reference (RSI 1995) M. Notcutt – Temperature compensation for cryogenic cavity stabilized lasers (JoPD-AP 1999) S. Cook – Laser-Frequency Stabilization Based on Steady-State Spectral-Hole Burning in Eu3+:Y2SiO5 (PRL 2015)