All-fiber high-power erbium-doped laser system generating optical pulses with a duration of 200 µs to 5 ms for fractional photo-rejuvenation.

An all-fiber high-power erbium-doped fiber laser (EDFL) source generating optical pulses from 200 µs to 5 ms with a stable rectangular envelope for fractional photo-rejuvenation is proposed and experimentally demonstrated. A master oscillator power amplifier (MOPA) configuration composed of a master oscillator, an acousto-optic modulator (AOM), and a one-stage amplifier is designed and employed in the EDFL to serve as an efficient laser system with excellent output performance. To avoid multistage amplifiers, the master oscillator generates 1.5 W, and a Yb-free Er-doped large-mode-area (LMA) active fiber is used for a one-stage power amplifier. There are two benefits to this approach: first, modulation of both pump and seed pulses is used to achieve clear rectangular shaped pulses without amplified spontaneous emission (ASE) growth; and second, there are no power limitations in the amplifier and undesirable 1 µm ASE compared to Er/Yb systems. We have reached 28.6 W of peak power with 26% slope efficiency limited only by available pump power, so the system can be easily scaled for achieving a higher peak power.

Broadband gain performance in the mid-IR using supercontinuum: 2.7 µm gain in high-purity Er3+doped tungsten tellurite glass fibers.

This paper presents an experimental study of broadband mid-IR amplification that is carried out, for the first time, to the best of our knowledge, in an erbium-doped tungsten tellurite fiber. A simple, robust supercontinuum source based on a tapered germanate fiber is developed as a seed input in the region of 1.5-3 µm. We show that gain by a factor of 5 on one pass can be achieved in the 2.7 µm range by pumping a low-cost, high-efficiency diode laser at 976 nm using high-purity tellurite glass fibers.

High-energy femtosecond pulse shaping, compression, and contrast enhancement using multicore fiber.

Nonlinear spatiotemporal dynamics of femtosecond pulses in a hexagonal seven-core silica fiber pumped by a sub-µJ 370 fs Er:fiber chirped pulse amplification (CPA) system were studied. Nonlinear pulse shaping and compression in the central core and pedestal coupling to the outer cores were directly measured by frequency-resolved optical gating. Further compression of the pulses spectrally broadened in the multicore fiber down to 53 fs was demonstrated. Two orders of magnitude contrast enhancement of the pulses after compression was observed.

Widely tunable mid-infrared fiber laser source based on soliton self-frequency shift in microstructured tellurite fiber.

A turnkey fiber laser source generating high-quality pulses with a spectral sech shape and Fourier transform-limited duration of order 100 fs widely tunable in the 1.6-2.65 µm range is presented. It is based on Raman soliton self-frequency shifting in the suspended-core microstructured TeO2-WO3-La2O3 glass fiber pumped by a hybrid Er/Tm fiber system. Detailed experimental and theoretical studies, which are in a very good agreement, of nonlinear pulse dynamics in the tellurite fiber with carefully measured and calculated parameters are reported. A quantitatively verified numerical model is used to show Raman soliton shift in the range well beyond 3 µm for increased pump energy.

Two-color optically synchronized ultrashort pulses from a Tm/Yb-co-doped fiber amplifier.

A method of producing high quality, optically synchronized two-color ultrashort pulses in an active thulium-doped fiber is proposed. We show that sech-shaped femtosecond pulses with essentially different wavelengths can be generated directly from a Tm/Yb-co-doped amplifier: one pulse at about 2 µm and the second pulse with a tunable wavelength up to 2.3 µm, which covers the pump and gain regions of Cr:ZnSe and Cr:ZnS amplifiers. The shortest pulses with durations of 145 fs at 2.25 µm and 125 fs at 2 µm were measured by the FROG (frequency-resolved optical gating) technique.

Generating tunable optical pulses over the ultrabroad range of 1.6-2.5 µm in GeO2-doped silica fibers with an Er:fiber laser source.

We report generation of femtosecond optical pulses tunable in the 1.6-2.5 µm range using GeO2-doped core silica-cladding fibers. Optical solitons with a duration of 80-160 fs have been measured by the FROG technique in the 2-2.3 µm range. To the best of our knowledge, these are the longest wavelength temporally characterized solitons generated in silica-based fibers. We have also demonstrated more than octave-spanning femtosecond supercontinuum generation in the 1.0-2.6 µm range.