C.J.S. de Matos

All-fiber chirped pulse amplification using highly-dispersive air-core photonic bandgap fiber

We show, for the first time to our knowledge, all-fiber chirped pulse amplification using an air-core photonic bandgap fiber. Pulses from a wavelength- and duration-tunable femtosecond/picosecond source at 10 GHz were dispersed in 100 m of dispersion compensating fiber before being amplified in an erbium-doped fiber amplifier and subsequently recompressed in 10 m of the anomalously dispersive photonic bandgap fiber. Pulses as short as 1.1 ps were obtained. As air-core fibers present negligible nonlinearity, the presented configuration can potentially be used to obtain ultra-high pulse peak powers. A study of the air-core fiber dispersion and dispersion slope is also presented.

Continuous-wave, totally fiber integrated optical parametric oscillator using holey fiber

We present, for the first time to our knowledge, a cw, all-fiber optical parametric oscillator that uses a holey fiber. The oscillator operates at 1.55 microns and can yield an oscillating parametric signal that consists of a single line with a 30-dB extinction ratio and a 10-pm linewidth or that consists of multiple lines. In addition to the signal and the idler, five other pairs of spectral lines can be observed that are due to multiple parametric interactions. The source reaches threshold for a pump power of 1.28 W and saturates for pump powers in excess of approximately 1.6 W.

Multi-kilowatt, all-fiber integrated chirped-pulse amplification system yielding 40× pulse compression using air-core fiber and conventional erbium-doped fiber amplifier

We present a totally fiber integrated chirped-pulse amplification system using air-core photonic bandgap fiber and a conventional erbium-doped fiber amplifier. ~40-ps input pulses, generated in a Mach-Zehnder modulator, were stretched and spectrally broadened in a dispersion-shifted fiber before being amplified and subsequently compressed in 10 m of anomalously-dispersive photonic bandgap fiber to yield ~960 fs pulses. The system gives multi-kilowatt peak powers while the amplifier nonlinearity threshold is as low as ~150 W. Higher peak powers could be obtained by the use of an amplifier with higher nonlinearity threshold.

Temporal and noise characteristics of continuous-wave-pumped continuum generation in holey fibers around 1300nm

The noise of continuous-wave-pumped broadband continua generated in a holey fiber is characterized in two different all-fiber configurations. An amplified spontaneous emission seeded ytterbium-doped fiber source and fiber Bragg grating based Yb laser were employed to initiate Raman-soliton continuum generation in 100m of anomalously dispersive holey fiber with spectral width of 300nm and spectral power density over 10mW/nm. Low noise operation makes these sources suitable for optical coherence tomography applications.

Tunable repetition-rate multiplication of a 10 GHz pulse train using linear and nonlinear fiber propagation

The temporal Talbot effect and soliton propagation in an optical fiber were exploited to yield a series of pulse train sources with tunable repetition rate simply through variation of the pulse train power in sections of the fiber. In a dual-repetition-rate configuration, 10 and 20 GHz or 10 and 30 GHz repetition rates could be achieved depending on the fiber length used, with pulse durations lower than 21 ps. In a triple-repetition-rate configuration, 10, 20, and 30 GHz repetition rates were obtained, with pulse durations lower than 15 ps.

Low-threshold self-induced modulational instability ring laser in highly nonlinear fiber yielding a continuous-wave 262-GHz soliton train

Modulational instability (MI) is employed in a self-induced ring cavity configuration based on highly nonlinear dispersion-shifted fiber (HNL DSF) and an erbium-doped fiber amplifier to generate a continuous-wave 262-GHz train of 365-fs optical solitons. The laser operates around 1540 nm, with an average output power of 15 mW. MI is achieved at a low threshold as a result of low average cavity dispersion and high fiber nonlinearity. It is shown that, because of the normal dispersion of the HNL DSF, the solitons exist in the average soliton regime.

Continuous-wave-pumped Raman-assisted fiber optical parametric amplifier and wavelength converter in conventional dispersion-shifted fiber

We present a continuous-wave-pumped fiber optical parametric amplifier, operating near 1539 nm in conventional dispersion-shifted fiber, with maximum on-off gain and wavelength-conversion efficiency of 13.7 and 13.1 dB, respectively. In addition, we show a novel configuration based on Raman amplification assistance in the parametric gain fiber that further increases the gain and wavelength-conversion efficiencies to 16.7 and 16.2 dB, respectively.

Short-pulse, all-fiber, Raman laser with dispersion compensation in a holey fiber

The use of Raman gain in conventional fiber followed by dispersion compensation in a holey fiber in a synchronously pumped laser configuration allowed compression by a factor of 8.5 of output pulses at a selected wavelength with respect to the pump pulses. We obtained 2-ps output pulses at 1.14 microm from a totally fiber-integrated laser pumped with 17-ps pulses at 1 microm. Higher pulse compression should be possible with nonlinear chirp compensation. Ultrashort-pulse, all-fiber Raman lasers at wavelengths shorter than 1.3 microm are feasible.

4× repetition-rate multiplication and Raman compression of pulses in the same optical fiber

A 21.7-km nonzero dispersion-shifted fiber was used to obtain 4x multiplication of the repetition rate of a 20-GHz train of 4.2-ps optical pulses through the temporal Talbot effect. Raman compression in the same fiber shortened and developed the pulses into 2.0-ps solitons and resulted in a lower duty cycle. It is shown that the linear Talbot effect and nonlinear Raman compression occurred in different sections of the fiber, the lengths of which could be varied through adjustments in the input pulse power.

20-kW peak power all-fiber 1.57-µm source based on compression in air-core photonic bandgap fiber, its frequency doubling, and broadband generation from 430 to 1450 nm

We demonstrate an ultrashort all-fiber-integrated chirped-pulse amplification system yielding 1-ps pulses with 20 kW of peak power. 40-ps initial pulses generated by an externally modulated laser diode are chirped by self-phase modulation in a conventional fiber, amplified, and compressed in 110 m of air-core photonic bandgap fiber. The compressed pulses are frequency doubled in a periodically poled KTP crystal with up to 48% efficiency and applied to supercontinuum generation in a holey fiber, resulting in a high-power uniform continuum that stretches from 430 to 1450 nm.