Predictable tuning behavior and stable laser operation are both crucial for laser spectroscopy measurements. We report a sampled grating quantum cascade laser (QCL) with high spectral tuning stability over the entire tuning range. We have determined the minimum loss margin required to suppress undesired lasing modes in order to ensure predictable tuning behavior. We have quantified power fluctu...

Long-period gratings were fabricated in standard telecommunication fiber (Corning SMF-28) by use of what is believed to be record short-wavelength light from a 157-nm F(2) laser. Strong loss peaks were formed without the need for enhancement techniques such as hydrogen loading. The magnitude of the attenuation peak was sensitive to the single-pulse laser fluence, decreasing with increasing puls...

The spatial stability of microscopic target droplets used for laser-plasma soft x-ray generation in vacuum is investigated. A long-term drift in drop position is characterized with an ultrafast laser-diode imaging system. The drift is experimentally and theoretically shown to be due to a temperature-induced increase in target-liquid viscosity as a result of evaporation. Finally, the drift is co...

A control algorithm is presented that addresses the stability issues inherent to the operation of monolithic mode-locked laser diodes. It enables a continuous pulse duration tuning without any onset of Q-switching instabilities. A demonstration of the algorithm performance is presented for two radically different laser diode geometries and continuous pulse duration tuning between 0.5 ps to 2.2 ...

The frequency stability of a 1560-nm diode laser, whose second harmonic was locked to (87)Rb sub-Doppler lines, was characterized by measuring the beat frequency relative to a 780-nm reference laser that was locked to sub-Doppler lines of another rubidium cell. The square root of the Allan variance reached a minimum value of 7.5 x 10(-12) in 1 s, which corresponded to frequency variations of 1....

Based on our earlier theoretical work on tracking periodic patterns into spatiotemporal chaotic regimes in spatially extended systems, we present in this article a case study of a high-aspectratio three-level laser. Following a detailed investigation into travelling wave solutions of the laser system and their stability conditions, we discuss ways of stabilising these solutions by local feedbac...

Diode laser absorption measurements obtained with two-tone frequency-modulation spectroscopy (TTFMS) are combined with tomography to produce spatially resolved quantitative images of fluid flows. The high sensitivity, good accuracy, and high stability of TTFMS absorption measurements permit optical-absorption tomography to be performed with low noise on extremely weakly absorbing objects. The m...

A stretched-pulse fiber laser with a nonlinear optical loop mirror (NOLM) that produces 100-fs pulses with 1-nJ energy is demonstrated. These results constitute a 30-fold increase in pulse energy over previously reported femtosecond fiber lasers with a NOLM. Compared with previous stretched-pulse lasers, this laser offers a cleaner spectrum and improved stability, with comparable pulse duration...

Accurate and traceable length metrology is employed by laser frequency stabilization. This paper describes a laser frequency stabilization technique as a secondary standard with a fractional frequency stability of 5.2x10(-10) with 2 mW of power, suitable for practical applications. The feedback stabilization is driven by an intrinsic mixed mode signal, caused by nonlinear optical phenomena with...

A system of two mutually delay-coupled semiconductor lasers with a small delay of 170 ps in the coupling is studied. Apart from a possible difference in their optical frequencies, we consider two identical lasers. We show the existence and stability of compound laser modes. They are the basic solutions of the system describing a frequency locked state of the coupled laser system. A characterist...