RESUMO
Light sources are used in optofluidic devices for real-time system control and quantitative analysis of important process parameters. In this work, we present a random laser source using a hollow-core antiresonant reflecting optical waveguide (HC-ARROW) containing the gain media inside a reservoir to reduce dye bleaching, which is connected to microchannel waveguides to increase beam directionality. The device is pumped externally and emits a highly coherent and collimated laser beam.
RESUMO
A wavefront sensor for thermally induced lens and passive lens characterization based on low-coherence digital speckle interferometry was developed and studied. By illuminating the optical setup with two slightly detuned red diode lasers, whole-field contour interference fringes were generated according to the resulting synthetic wavelength. For fringe pattern visualization the optical setup used the light transmitted through a ground glass plate as object beam. The performance of the sensor was investigated and its versatility was demonstrated by measuring the thermal lens induced in an Er-doped glass sample pumped by a 1.76-W diode laser emitting at 976 nm and by evaluating the wavefront distortion introduced by an ophthalmic progressive lens.
RESUMO
Measurements of the bifocal, thermally induced lenses of a cw Nd:YAG laser were obtained. We observed four different focal lengths that are polarization and direction dependent. The focal lengths were used to design stable resonators with large fundamental mode filling in the laser gain medium. The beam is totally polarized in the desired direction even without an intracavity Brewster window. We developed a general approach for the optimization of single-lamp, cw-pumped Nd:YAG lasers. Up to 22 W of cw output power in the vertically polarized TEM(00) mode and 15 W in the horizontal polarization are obtained for moderate lamp currents. Also, we demonstrate mode locking with 56-ps pulse duration at 33 A of lamp current and up to 13 W of average output power.
RESUMO
Passive stable mode locking of a pulsed Nd:YAG laser was achieved with a long-decay-time saturable absorber in a coupled-cavity longitudinal scheme. In this configuration the saturable absorber (LiF:F(2) ) also behaves as an active medium in intracavity pumping and is the load for the Nd laser. This arrangement provides proper lasing conditions for the F(2) color centers so that the cavity photon lifetime of the color centers is much shorter than the cavity round-trip time of the Nd laser. In this way the Nd pulses are simultaneously Q switched and mode locked. The pulses show a stable temporal profile, with an envelope of 160 ns and a train of mode-locked pulses of less than 200-ps duration.
