Fiber laser optical frequency
standard at 154 μm

Abstract

A 32 mW fiber laser is stabilized to the (13)C(2)H(2) P(16) (ν1 + ν3) transition at 1542 nm using saturated absorption. The short-term shot-noise limited fractional frequency instability is 5.0 × 10(-13)(τ/s)-½ for averaging times τ up to about 100 s. The relative lock-point repeatability over 2½ month is 4.3 × 10(-13) corresponding to 83 Hz. The simple setup includes a 21 cm long gas cell, but it does not require an enhancement cavity or external modulators. The spectroscopic lineshape is analyzed with respect to optical power and acetylene pressure. Narrow linewidths of 300 kHz FWHM are observed with a signal to noise ratio of 35 dB in a 9 Hz bandwidth.

Optical frequency standard using acetylene-filled hollow-core photonic crystal fibers

“…The performance achieved improves previously published results [12,15] for gas-filled HC fibers both in terms of frequency stability and lock-point repeatability, reducing the gap with respect to the performance achieved with bulk glass cells [7].…”

“…A small fraction of the laser output is combined with the output of a reference laser and the resulting beat signal is monitored with a fast photodiode and a frequency counter. The reference laser is locked to an an acetylene bulk glass cell as described in [7] and it has a frequency instability (Allan deviation) below 5×10 −13 for sampling time 1 < τ < 10 5 s and a lock-point repeatability of about 100 Hz.…”

“…In the telecommunication band the 13 C 2 H 2 P(16) (ν 1 + ν 3 ) line at 1542.3837 nm is the recommended optical transition for the realization of the meter [1]. During the last decade, I 2 , acetylene and Rb vapour cells have been widely investigated and implemented in laser stabilization using the saturated absorption spectroscopy (SAS) technique [2], often combined with frequency modulated spectroscopy [3][4][5][6][7]. Since the demonstration of the first photonic band gap guidance in air [8], the increased availability of fibers with an hollow core (HC) allowed to investigate the realization of a portable optical frequency reference based on a gas-filled HC fiber [9][10][11][12][13].…”

Interference Cancellation for Hollow-Core Fiber Reference Cells

“…Two circulators are used to monitor both the transmitted probe and the pump using two photodetectors (PD). The frequency is controlled by offset-locking of the laser to a second acetylene stabilized laser described in [8]. The acetylene-filled fiber is the same as the one shown in Fig.…”

“…As a third measurement method, recent results with the same HCF cell, using pump and probe light at different frequencies [8] are shown for comparison.…”