We present a dual-comb spectrometer based on two passively mode-locked waveguide lasers integrated in a single Er-doped ZBLAN chip. This original design yields two free-running frequency combs having a high level of mutual stability. We developed in parallel a self-correction algorithm that compensates residual relative fluctuations and yields mode-resolved spectra without the help of any reference laser or control system. Fluctuations are extracted directly from the interferograms using the concept of ambiguity function, which leads to a significant simplification of the instrument that will greatly ease its widespread adoption and commercial deployment. Comparison with a correction algorithm relying on a single-frequency laser indicates discrepancies of only 50 attoseconds on optical timings. The capacities of this instrument are finally demonstrated with the acquisition of a high-resolution molecular spectrum covering 20 nm. This new chip-based multi-laser platform is ideal for the development of high-repetition-rate, compact and fieldable comb spectrometers in the near- and mid-infrared.

We present an original instrument designed to accomplish high-speed spectroscopy of individual optical lines based on a frequency comb generated by pseudo-random phase modulation of a continuous-wave (CW) laser. This approach delivers efficient usage of the laser power as well as independent control over the spectral point spacing, bandwidth and central wavelength of the comb. The comb is mixed with a local oscillator generated from the same CW laser frequency-shifted by an acousto-optic modulator, enabling a self-heterodyne detection scheme. The current configuration offers a calibrated spectrum every 1.12 µs. We demonstrate the capabilities of the spectrometer by producing averaged, as well as time-resolved, spectra of the D1 transition of cesium with a 9.8-MHz point spacing, a 50-kHz resolution and a span of more than 3 GHz. The spectra obtained after 1 ms of averaging are fitted with complex Voigt profiles that return parameters in good agreement with expected values.

This paper presents an open and flexible digital phase lock loop optimized for laser stabilization systems. It is implemented on a cheap and easily accessible FPGA-based digital electronics platform (Red Pitaya) running a customizable open-source firmware. A PCbased software interface allows controlling the platform and optimizing the loop parameters remotely. Several tools are included to allow measurement of quantities of interest smoothly and rapidly. To demonstrate the platform's capabilities, we built a fiber noise canceler over a 400 m fiber link. Noise cancellation was achieved over a 30 kHz bandwidth, a value limited mainly by the delays introduced by the actuator and by the round-trip propagation over the fiber link. We measured a total latency of 565 ns for the platform itself, limiting the theoretically achievable control bandwidth to approximately 225 kHz.

We demonstrate a generalized method for dual-comb interferometry that involves the use of two frequency combs with quasi-integer-ratio repetition rates. We use a 16.67 MHz comb to probe an 80-cm-long ring cavity and a 100 MHz comb to asynchronously sample its impulse response. The resulting signal can be seen as six time-multiplexed independent interferograms. We perform a deconvolution of the photodetector's impulse response to prevent any crosstalk between these multiplexed data sets. The measurement is then demultiplexed and corrected with referencing signals. We obtain a measurement with a spectral point spacing of 16.67 MHz and a spectral SNR of 55 dB by averaging 15,000 interferograms, corresponding to a measurement time of 500 s. Compared to conventional dual-comb spectroscopy, this generalized technique allows to either reduce the spectral point spacing or the acquisition time by changing the repetition rate of only one of the combs.

We report mode-locked ~1550 nm output of transform-limited ~180 fs pulses from a large mode-area (diameter ~50 μm) guided-wave erbium fluorozirconate glass laser. The passively mode-locked oscillator generates pulses with 25 nm bandwidth at 156 MHz repetition rate and peak-power of 260 W. Scalability to higher repetition rate is demonstrated by transform-limited 410 fs pulse output at 1.3 GHz. To understand the origins of the broad spectral output, the laser cavity is simulated by using a numerical solution to the Ginzburg-Landau equation. This paper reports the widest bandwidth and shortest pulses achieved from an ultra-fast laser inscribed waveguide laser.