Richard Ferriere

All-fiber source of 20-fs pulses at 1550 nm using two-stage linear-nonlinear compression of parabolic similaritons

Parabolic pulses from a similariton amplifier at 1550nm are compressed using a two-stage fiber compressor employing linear compression in photonic bandgap fiber and soliton effect compression in highly nonlinear fiber. Precise optimization of the compressor design using frequency resolved optical gating allows the generation of minimally chirped pulses as short as 20fs. This duration corresponds to only four optical cycles of the underlying electric field at this wavelength

Time-of-flight range detection using low-frequency intensity modulation of a cw laser diode: application to fiber length measurement

This paper describes a simple optical range detector in the time-of-flight (TOF) category using a cw laser diode emitting at 1.55 µm. The principle of operation combines TOF with frequency-modulated cw methods. The main originality of this method consists in measuring the time delay between two signals without using the time variable. The forward current of the laser diode is modulated by a low-frequency triangular signal. The emitted and received signals are compared, and the amplitude difference gives a readout signal whose peak-to-peak amplitude is proportional to the TOF. An application to optical fiber length measurement is given.

Effect of depth etching on Bragg reflectors realized by focused ion beam in Ti:LiNbO3 waveguide

In this paper we have studied effect of depth etching on the Bragg gratings (BGs) realized by Focused Ions Beam. This technique has the advantage to induce a direct waveguide structuring without intermediate media, comparing to traditional methods. A reflectivity of 96% within a window centred at 1550 nm is obtained. The effect of the depth etching on the transmittance and the bandwidth at half maximum is demonstrated.

Control and compression of extreme spectrally-broadened pulses in highly nonlinear fiber

Nonlinear pulse compression techniques are of course very well-known, exploiting the initial spectral broadening and temporal compression phase of higher-order soliton evolution in the anomalous dispersion regime of an optical fiber. However, the presence of effects such as Raman scattering, higher-order dispersion or input pulse noise can induce pulse break-up and instabilities through soliton-fission processes. Recent studies of soliton fission in the context of supercontinuum generation have provided improved insight into the way these processes can be avoided, allowing significant improvement in achievable compressed pulse quality and duration. In this paper we focus on providing an overview of a series of our own experiments around 1550 nm where we have used parabolic pulse similariton amplifiers to generate low noise pulses that have been linearly and nonlinearly compressed to the sub-30 fs regime using controlled compression in highly nonlinear fiber. In addition, we also describe recent results where comparable pulse durations have been obtained using sub-10 cm lengths of highly nonlinear fiber directly spliced to the output pigtail of a commercial femtosecond source.

Generation of ultrafast Bessel micro-beams and applications to laser surface nanoprocessing

The novel propagation characteristics of Bessel beams have been widely applied to optical manipulation and harmonic generation, and have provided new perspectives on fundamentals of ultrashort laser pulse propagation in nonlinear media. Fully exploiting their many unique properties, however, requires the development of techniques for the generation of high quality Bessel beams with flexible adjustment of the beam parameters. Moreover, long working distances are needed to produce Bessel beams inside bulk samples. In this paper, we report on the development of a novel spatial light modulator based setup that combines the properties of parameter flexibility, long working distance, high throughput and operation on micron-scale. We report both on the general characterization of the beam properties as well as a specific application in surface nanoprocessing.