Operation of an optically coherent frequency comb outside the metrology lab

Abstract

We demonstrate a self-referenced fiber frequency comb that can operate outside the wellcontrolled optical laboratory. The frequency comb has residual optical linewidths of < 1 Hz, subradian residual optical phase noise, and residual pulse-to-pulse timing jitter of 2.4 -5 fs, when locked to an optical reference. This fully phase-locked frequency comb has been successfully operated in a moving vehicle with 0.5 g peak accelerations and on a shaker table with a sustained 0.5 g rms integrated acceleration, while retaining its optical coherence and 5-fs-level timing jitter. This frequency comb should enable metrological measurements outside the laboratory with the precision and accuracy that are the hallmarks of comb-based systems.Work of the U.S.

Optical Frequency Comb Generation based on Erbium Fiber Lasers

“…Erbium fiber lasers that are mode-locked with a SESAM usually show excellent self-starting properties and a high degree of reproducibility. The laser cavity requires only the SESAM and a wavelength division multiplexer to introduce the pump light, making this one of the simplest cavity designs among all mode-locked erbium fiber lasers [67,101]. When used in a linear configuration, the cavity length of a SESAM laser can be very short, and lasers with repetition rates above 1 GHz have been constructed [103,121].…”

“…When used in a linear configuration, the cavity length of a SESAM laser can be very short, and lasers with repetition rates above 1 GHz have been constructed [103,121]. Additionally, this concept allows for an all-fiber and also all-PM design, which results in exceptionally robust and environmentally stable lasers [67].…”

“…At higher modulation frequencies, acoustic modes in the optical fiber or in the mounting structures can resonate, leading to large phase shifts that limit the achievable feedback bandwidth. However, with careful attention to the suppression of these resonances, bandwidths of 100 kHz or beyond are possible [67,70,156]. A single PZT requires large drive voltage to achieve moderate modulation depths, which is experimentally challenging.…”

“…Moreover, the flexibility of the fiber-based platform and the ubiquity of low cost, high quality components in the erbium gain window has spurred research into different oscillator designs (see Sec. 3), multi-branch frequency combs [42][43][44][45], difference frequency generation to other wavelength bands [46][47][48][49][50][51][52], variable repetition-rate systems [53][54][55][56], synthesis of arbitrary optical frequencies [57][58][59][60][61][62][63][64], and robust fieldable systems [65][66][67][68][69][70][71]. In fact, one could argue that a significant majority of the demonstrations of comb applications have been done with erbium fiber lasers, driven largely by the rapidly maturing erbium comb technology.…”

Spectral Methods for Determining the Stability and Noise Performance of Passively Modelocked Lasers

“…Some examples are GaAs Bragg mirrors [14], nanotubes [15], and graphene saturable absorbers [16]. In nano-scale semiconductor laser diodes, the saturable absorber can also be integrated monolithically in the quantum well/dot structure by electrically isolating one section of the device [17,18].…”