A transmitter unit for emitting radiation into the surrounding area, including at least one semiconductor laser, which has at least one first emitter possessing a first section and a second section; and at least one control unit for controlling the semiconductor laser. The control unit is configured to apply a first supply variable to the first section of the at least one emitter, and to apply a second supply variable differing from the first supply variable, to the second section of the at least one emitter.

There is provided a Q-switched semiconductor light-emitting element, including a comb electrode that has at least two or more gain regions and two or more absorption regions, the regions including an active layer and being continuous on a semiconductor substrate, separation regions being provided between the gain regions and the absorption regions, the longest region of the gain regions being located on a rear end surface side; and an optical waveguide that staddles the gain regions, the absorption regions, and the separation regions.

A semiconductor laser drive circuit includes: an anode electrode divided into at least one gain region and at least one light absorption region; a cathode electrode shared between the gain region and the light absorption region; and a resistance connected to the anode electrode of the light absorption region.

A system for resonantly enhanced frequency conversion includes a nonlinear crystal for frequency converting a pump laser beam, and mirrors forming a ring resonator for the pump laser beam such that a closed propagation path of the pump laser beam, inside the ring resonator, passes through the nonlinear crystal. The mirrors include an adaptive mirror, a curved-mirror pair positioned in a first segment of the propagation path spanning between the adaptive mirror and the nonlinear crystal, and an input coupler for coupling the pump laser beam into the ring resonator. The curved-mirror pair forms an imaging system having conjugate planes at the adaptive mirror and the nonlinear crystal. The input coupler is positioned in a second segment of the propagation path that spans between the adaptive mirror and the nonlinear crystal and does not include deflection by the curved-mirror pair.

A passively Q-switched laser with intracavity pumping is described. The passively Q-switched laser has an optically pumped gain element and a saturable absorber element. The optically pumped gain element is situated in an extended cavity of a VECSEL (Vertical Extended Cavity Surface Emitting Laser) so that the gain element is pumped by a circulating pump beam of the VECSEL. The passively Q-switched laser may produce output pulses at an eye-safe wavelength using a low gain laser transition and may use a plurality of surface emitting gain regions to pump the passively Q-switched laser.

This invention discloses an improved laser induced breakdown spectroscopy (LIBS) apparatus and method for the detection of mineral and metal contamination in liquid samples. The mineral and metal contaminant is first collected by filtering the liquid sample with a membrane filter. The membrane filter with the mineral and metal contaminant is then measured by a LIBS apparatus. The LIBS apparatus is based on a high repetition rate pulsed laser. The laser produces a train of laser pulses at a high repetition rate in the kHz (or even higher) range. When the laser beam hits the surface of the membrane filter, it generates several thousands of micro-plasma emissions per second. Synchronized miniature CCD array optical spectrometer modules collect the LIBS signal from these micro-plasma emissions. By adjusting the integration time of the spectrometer to cover a plurality of periods of the laser pulse train, the spectrometer integrates the LIBS signal produced by this plurality of laser pulses. Hence the intensity of the obtained LIBS spectrum can be greatly improved to increase the signal-to-noise ratio (SNR) and lower the level of detection (LOD).

A monolithic QCL/APD IR Transceiver in which the QCL transmitter and APD receiver have the same N MQW stage composition and variation in thickness in the z direction for all positions in x and y directions. The heterostructure is configured via asymmetric stages, additional stages for the APD or by reversing the polarity of the p-n junction for the APD or a combination thereof such that the upper energy state in the QCL under forward bias is confined to the quantum well and in the APD under reverse bias is near the top of the quantum well in energy and localized in the quantum well to spatially overlap with the lower energy state to facilitate detection of echo photons. The QCL and APD may be positioned end-to-end, side-by-side or as a common region of the heterostructure.

A vertical external-cavity surface-emitting laser includes: a resonator comprising at least two mirrors; a semiconductor laser medium disposed in the resonator; and a Q switch provided in the resonator.

A device for generating a laser pulse. The device includes a laser diode that includes a first diode and a second diode, so that the laser diode includes a first anode, a second anode, and a cathode. The device further includes a first voltage potential that is electrically connected to the second anode, a second voltage potential that has a lower value than the first voltage potential, a first switch that is electrically connected to the first anode and to the second voltage potential, and a second switch that is electrically connected to the cathode and to the second voltage potential. A resistor is electrically connected to the first anode and to the second anode.

Systems and methods for imaging in the short wave infrared (SWIR), photodetectors with low dark current and associated circuits for reducing dark currents and methods for generating image information based on data of a photodetector array. A SWIR imaging system may include a pulsed illumination source operative to emit radiation pulses in the SWIR band towards a target resulting in reflected radiation from the target; (b) an imaging receiver including a plurality of Ge PDs operative to detect the reflected SWIR radiation and a controller, operative to control activation of the receiver for an integration time during which the accumulated dark current noise does not exceed the time independent readout noise.