ASE recirculation effects in pulsed frequency shifted feedback lasers at large frequency shifts.

An analysis of the different emission regimes (continuous wave, Q-switched, and different forms of modelocking) of a C-band Er:fiber frequency shifted feedback laser at large frequency shifts is presented. We clarify the role of amplified spontaneous emission (ASE) recirculation in the origin of various spectral and dynamical properties of this type of laser. Specifically, we show that Q-switched pulses are supported by a noisy, quasiperiodic ASE recirculation pattern that univocally identifies the pulses within the sequence, and that these Q-switched pulses are chirped as a consequence of the frequency shift.

All-optical coherent pulse compression for dynamic laser ranging using an acousto-optic dual comb.

We demonstrate a new and simple dynamic laser ranging platform based on analog all-optical coherent pulse compression of modulated optical waveforms. The technique employs a bidirectional acousto-optic frequency shifting loop, which provides a dual-comb photonic signal with an optical bandwidth in the microwave range. This architecture simply involves a CW laser, standard telecom components and low frequency electronics, both for the dual-comb generation and for the detection.

Phase sensitive low-coherence interferometry using microwave photonics.

We report on a low-coherence interferometer based on Microwave Photonics (MWP) which allows, for the first time to the best of our knowledge, stable determination of the interferogram's phase. The interferometer is built on suppressed carrier, double-sideband modulation, dispersive propagation in a chirped fiber Bragg grating, demodulation by electro-optical frequency down-conversion, and suitable signal processing techniques to account for modulation impairments. Taking as a reference a direct normalization of the link's microwave response, the system retrieves high-resolution interferograms, both in amplitude and phase and free from distortion induced by higher-order dispersion, in an optical path difference of 16.

Far-field Talbot waveforms generated by acousto-optic frequency shifting loops.

We report on the description of the optical fields generated by acousto-optic Frequency-Shifting Loops (FSL) in the temporal Fraunhofer domain when the loop is operated in the vicinity of integer or fractional Talbot conditions. Using self-heterodyne detection, we experimentally demonstrate the equivalence of the Talbot phases generated at fractional conditions with the Gauss perfect phase sequences, and identify deviations from the standard frequency-to-time mapping description of the far field. In particular, we show the existence of ripples in the pulse intensity, of unavoidable pulse-to-pulse interference in the pulse train, of small oscillations, of the order of hundreds of MHz, in the expected linear pulse chirp, and the capture of the phase at the pulse's trailing edge by the adjacent pulse.