High-performance, vibration-immune, fiber-laser frequency comb

Abstract

We demonstrate an environmentally robust optical frequency comb based on a polarization-maintaining, all-fiber, figure-eight laser. The comb is phase locked to a cavity-stabilized cw laser by use of an intracavity electro-optic phase modulator yielding 1.6 MHz feedback bandwidth. This high bandwidth provides close to shot-noise-limited residual phase noise between the comb and cw reference laser of -94 dBc/Hz from 20 Hz to 200 kHz and an integrated in-loop phase noise of 32 mrad from 1 Hz to 1 MHz. Moreover, the comb remains phase locked under significant mechanical vibrations of over 1 g. This level of environmental robustness is an important step toward a fieldable fiber frequency comb.

Coherent dual-comb spectroscopy at high signal-to-noise ratio

“…As a result, it is much more important to generate combs with strong, spectrally flat, phase coherent spectra than are used for clock applications. EOM based frequency combs [61,62] offer a promising path to suppress phase noise but the flat spectra remains a challenge. Moreover, to realize the full potential of this approach, one would like these spectra to extend well beyond the gain region of available laser sources and into the mid-infrared, long wave-infrared and THz regions [1,21].…”

Optical Frequency Comb Generation based on Erbium Fiber Lasers

“…A figure-of-eight erbium fiber laser can use all-PM fibers, making it alignment-insensitive and environmentally robust [68,116]. Like NPE lasers, the nonlinear loop mirror is effectively a fast absorber and low-dispersion cavities can be constructed.…”

“…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.…”

All polarization-maintaining fiber laser architecture for robust femtosecond pulse generation

“…Without such nonreciprocal phase bias, the transmission for low intensity is close to zero and does not offer any intensity dependence. This strongly impedes self-starting and has led to efforts to actively start the mode-locking [11,12]. Recently, it has been shown by several groups that self-starting ability can be achieved by introducing a nonreciprocal phase bias in the NOLM loop [4,13,14] using a proper arrangement of Faraday rotators and waveplates.…”