L. Lefort

Practical low-noise stretched-pulse Yb 3+ -doped fiber laser

We report on the development of what we consider to be a practical and highly stable stretched-pulse laser based on Yb(3+) -doped silica fiber. The Fabry-Perot cavity uses nonlinear polarization rotation as the mode-locking mechanism, and a semiconductor saturable-absorber mirror to ensure robust self-starting and incorporates a diffraction grating pair to compensate for the normal dispersion of the fiber. Use of a single-mode grating-stabilized telecommunications-qualified pump laser diode ensures reliable, low-noise operation (~0.05% amplitude fluctuations at 10-Hz measurement bandwidth). The laser generates high-quality, 60-pJ pulses of <110-fs duration at a repetition rate of ~54 MHz (3-mW average power).

Generation of femtosecond pulses from order-of-magnitude pulse compression in a synchronously pumped optical parametric oscillator based on periodically poled lithium niobate

We demonstrate the generation of compressed, transform-limited 250-fs pulses, tunable in the near infrared, by means of synchronously pumped optical parametric oscillation in periodically poled lithium niobate. The almost 20-fold compression from the 4-ps pulse duration of the cw mode-locked Nd:YLF pump results in signal peak powers well in excess of the pump power.

Efficient, low-threshold synchronously-pumped parametric oscillation in periodically-poled lithium niobate over the 1.3 μm to 5.3 μm range

Abstract Using periodically-poled lithium niobate (PPLN), synchronously pumped by a Nd:YLF laser at 1047 nm, optical parametric oscillation is achieved with a mean threshold power as low as 7.5 mW, nearly an order of magnitude lower than previously reported. Output slope efficiencies (signal plus idler), at a signal wavelength of ∼1.7 μm (idler 2.7 μm), of up to 160% are observed. Efficient operation has been observed out to 5.3 μm, well into the infrared absorption edge of lithium niobate.

Broad tuning around degeneracy in a singly resonant synchronously pumped parametric oscillator by means of a diffraction grating

The use of a diffraction grating as a frequency-selective reflector, has allowed a synchronously pumped optical parametric oscillator based on periodically poled lithium niobate to tune over a wide range, 1900–2300 nm around degeneracy (2094 nm), on a single periodically poled lithium niobate grating at a fixed temperature. The grating ensures stable singly resonant operation over the whole of this range except for a very narrow range at degeneracy, where doubly resonant behavior is evident. The extent of this narrow range, ∼6 nm, is confirmed by analysis.

A practical, low-noise, stretched pulse Yb/sup 3+/ doped fiber laser

Summary form only given. Yb/sup 3+/ doped silica fibers represent an attractive medium for the generation and amplification of ultrashort pulses. We demonstrated the first short pulse Yb/sup 3+/ silica fiber oscillator in 1996. Although good self-starting performance was obtained and <100fs pulses were generated, the cavity was of a complex design, incorporating an optical circulator arrangement and an intracavity prism based dispersion compensator. Moreover, it was pumped with a Ti:sapphire laser. We report the development of a far more practical and stable diode-pumped system, that we consider will prove highly attractive for a wide range of scientific and industrial applications.

Nonlinear pulse compression, dispersion compensation, and soliton propagation in holey fiber at 1 micron

We fabricated a single mode, polarization maintaining, highly non-linear, 125 micron silica jacketed, holey fiber with anomalous dispersion at 1.06 micron. Nonlinear pulse compression and soliton propagation are demonstrated (1.06 micron, Yb3+ source) with just 1 mW average power.

Fibre-laser-pumped femtosecond PPLN optical parametric oscillator

High-power fibre laser systems are an emerging technology for compact, robust and stable generation of ultrashort pulses. Their power levels have now converged with the power levels needed for efficient frequency conversion in quasi-phase-matched nonlinear materials such as periodically poled LiNbO/sub 3/ (PPLN). The combination of these two technologies is seen as an attractive method for producing broadly tunable ultrashort pulses. We present results of a synchronously pumped optical parametric oscillator (SPOPO) in PPLN, pumped by an Yb-doped fibre laser source in a master oscillator power amplifier scheme. The operating characteristics of this system are described, including its tuning behaviour, and the role of group velocity dispersion.

Generation of femtosecond pulses from order of magnitude pulse compression in a cw synchronously pumped optical parametric oscillator

Efficient sources of tunable coherent radiation in the near- and mid-IR, in the femtosecond time domain, are necessary for many applications including spectroscopy and communications. We report on the generation of tunable 200-fs pulses obtained from an optical parametric oscillator (OPO) synchronously pumped by a 4-ps cw mode-locked Nd:YLF source (/spl lambda/=1.047 /spl mu/m). Pulse compression in synchronously pumped OPOs has been previously demonstrated at high powers. We present, what we believe to be, the first demonstration of the extension of this technique to low-power cw mode-locked devices pumped by diode lasers. This is made possible by the use of periodically poled lithium niobate, which provides the required gain for much lower pump powers. The compressed pulses show excellent stability, high conversion efficiency, and peak powers exceeding that of the pump.

Optical Parametric Oscillation Beyond 6.3/spl mu/m in Periodically-Poled Lithium Niobate

Periodically poled lithium niobate has long been considered a very reliable material for use in optical parametric oscillators operating out to the absorption edge at ~4.5µm. The very high gains achieved when using mode-locked pulses to synchronously pump such devices, however, permit oscillation even with strong idler absorption. We present an analysis of operation under such conditions. Calculations indicate that operation to ~7µm should be possible. Oscillation at idler wavelengths out to 6.3µm has been observed.

Efficient cw synchronously pumped optical parametric oscillation beyond 5 /spl mu/m in periodically poled lithium niobate

Periodically poled lithium niobate (PPLN) offers many attractive features for optical parametric oscillation (OPO). These include high nonlinearity and noncritical quasi-phase-matching in a wide spectral range, making it well-suited to synchronously pumped operation. Using a cw mode-locked 1047-nm pump, we recently demonstrated a low-threshold singly resonant oscillator tunable over the range 1.67-2.8 /spl mu/m. In this contribution we report a major extension of this tuning range, demonstrating singly resonant operation in the range 1.3-5.3 /spl mu/m, while still retaining low threshold and high efficiency. Additionally we have observed oscillations with idler wavelengths out to 6.3 /spl mu/m. This now offers a widely tunable source covering wavelengths well into the mid-IR. This is made possible by the use of PPLN, which allows operation at longer wavelengths than bulk lithium niobate. In addition, the high round trip gain in pulsed pumping of PPLN-based OPOs allows generation of coherent, tunable radiation even in spectral regions where the crystal is highly absorbing. Thus, pumping with a mode-locked 1047-nm Nd:YLF laser, we were able to generate 10 mW of idler average power at 5.3 /spl mu/m for 800 mW of incident pump power, with an oscillation threshold of under 300 mW. We also present results of the coupled-wave analysis of parametric oscillation in the presence of idler absorption.