Abstract: Laser diode circuitry that controls the laser diode temperature as a function of laser diode current. Changes in the spectral output of the laser diode directly caused by adjustments to the operating current of the laser diode are offset by corresponding changes in the diode temperature. Diode temperature regulation circuitry automatically changes the diode temperature by monitoring the diode operating current. Alternately, when the diode current is adjusted to intentionally shift the spectral output of the diode, for example to maintain a frequency match to an external cavity resonance, the temperature regulation circuitry automatically changes the diode temperature to induce an additional spectral shift in the same direction, thereby inducing a current adjustment in the opposite direction that prevents large excursions in the amplitude of the operating current of the diode.

Abstract: A method of making 1.times.2 or 2.times.2 overclad couplers, switches and the like such that the process is more reproducible and loss characteristics are improved. Such couplers are typically made by inserting the stripped portions of two active optical fibers into a tube, heating the tube midregion to collapse it onto the fibers and stretching the central portion of the collapsed midregion to achieve the desired coupling characteristics. The improvement involves the insertion of one or two spacer fibers into the tube bore along with the active fibers to take up empty space that had been present in tube bore and to prevent an active fiber from sagging and crossing over the other fiber when the tube is heated during the tube collapse step.

Abstract: A pair of elongated, parallel electrodes (91,92) are insulatively mounted within a tubular housing (111) filled with a laser gas mixture between an arrangement of reflective optical elements (120,150) sealingly mounted at each end of the housing. The electrodes form a rectangular gas discharge area (40) the minimum spacing (a) between which is the diameter of the fundamental free-space mode of the stable, laser resonator (17) formed in the gap when the electrodes are rf excited (13). A multi-pass optical configuration (30,50) uses the full width (b) of the active medium to produce a high power, compact laser (10,200). Deformable support rings (97) are compressed to push the electrodes apart against small cylindrical spacers (99) abutting the inner walls of the housing to maintain the electrodes' spatial relationship. The rf feeds (103) sealingly (112) connected to the electrodes through the housing without disturbing the uniform distribution of forces on the electrodes.

Abstract: A mirrorless, distributed-feedback (DFB), ultraviolet, tunable, narrow-liidth, solid state laser for remote sensing and medical applications is disclosed. Optical pumping in the DFB laser is accomplished using a frequency quadrupled, 10 Hz., Q-switched, Nd:YAG laser operating at 266 nm. The pump beam is diffracted off a grating (2400 grooves per mm.) into two parts. The two beams are subsequently recombined at the side face of the Ce:doped crystal (8 mm.times.8 mm.times.30 mm) at an angle of about 2.theta.(about 81 degrees). The resulting spatially periodic excitation within the Ce-doped gain medium due to the interferring pump beams determines the operating wavelength of the DFB laser.

Abstract: An apparatus and method is disclosed for treating vascular lesions. In the preferred embodiment, an intracavity, frequency doubled Nd:YAG laser is used to generate output pulses having a duration of 0.5 to 10.0 milliseconds. This laser output is used to irradiate the lesions. The laser energy is absorbed in the blood of the vein, causing it to coagulate and collapse. The long pulse duration helps to minimize bleeding while controlling thermal damage to surrounding tissue.

Abstract: A laser oscillator has a casing 10. A cooling medium is supplied from an inlet port 134 to a heat exchanger 8 via a pipe 35, and discharged form it via a pipe 37 and an outlet port 136. The ports 134 and 136 are symmetrically positioned relative to a center line of the casing when seen from upward. An inlet port 340 and an outlet port 342 have a similar positional relation ship thereto.

Abstract: An intracavity modulated pulsed laser and methods of using the same. In one preferred form, an intracavity modulated pulsed laser comprises an amplification medium, a pulsed pumping source, a beam modulator, and two mirrors, one totally reflective and one partially reflective for generating at least one laser output burst comprising a plurality of sub-pulses having variably controllable peak powers. In another preferred form, a non-linear crystal is utilized to double the frequency of each laser output burst. In still another preferred form, a fluorescence feedback control circuit is utilized to control the beam modulator.

Abstract: A laser oscillator has a casing 10. A cooling medium is supplied from an inlet port 134 to a heat exchanger 8 via a pipe 35, and discharged form it via a pipe 37 and an outlet port 136. The ports 134 and 136 are symmetrically positioned relative to a center line of the casing when seen from upward. An inlet port 340 and an outlet port 342 have a similar positional relation ship thereto.

Abstract: A laser oscillator system has prolonged service lives of optical components thereof by preventing dust and the like from being produced from heat exchanger, the heat exchanger being reduced in size, and further, generates a higher laser beam output. The laser oscillator system uses a plate type heat exchanger as a cooling unit. The plate type heat exchanger can be made free of dust and the like, during a process of manufacturing it. Hence, it is possible to prevent inclusion of dust and the like from the heat exchanger into a laser oscillator and, thereby, markedly prolong the service lives of optical component parts. Further, the plate type heat exchanger is reduced in size and weight, which makes it possible to simplify a laser gas-circulating system. Further, influence of presence thereof, such as vibrations transmitted therefrom and the like, adversely affecting an electric discharge tube and the like, is reduced.

Abstract: A Transverse Excitation (TE) laser that produces a uniform discharge by utilizing a layered resistive electrode assembly, which includes a layer of positive temperature coefficient material that works in combination with a layer of negative coefficient material. The layered resistive electrode assembly distributes the discharge current uniformly throughout the electrode assembly and the associated gas discharge, and compensates for temperature induced resistivity variations of the electrode assembly.

Abstract: A tunable laser produces laser emission at at least two wavelengths simuleously. The tunable laser includes at least two gain elements, where each gain element generates a different wavelength. Means for optically exciting each laser gain element is appropriately disposed for either end pumping or side pumping to produce a laser emission within a preselected range of wavelengths. A wavelength dispersing element such as a prism is disposed in the laser resonator cavity for dispersing the wavelengths operating simultaneously within the laser resonator cavity and to create separate regions for each laser gain element. Laser gain elements may be tunable laser gain elements or discrete emitting laser gain elements. Arbitrarily large wavelength separations between the wavelengths operating simultaneously may be achieved in this manner producing stable cw or pulsed output, Q-switched or line narrowed depending on the means disposed within the laser resonator cavity.

Abstract: The lasing output of a laser diode (1) is controlled by the current through the diode (1). The laser diode (1) is driven by a switched mode drive circuit in which a pulsed signal is applied to a smoothing circuit, typically including a capacitor C and an inductor L, arranged to provide a smoothed output voltage whose magnitude depends on the pulse width of the drive signal.

Abstract: The control circuit for supplying a driving current to a laser diode makes it possible to keep the laser driving current variable in a wide range.

Abstract: In order to improve a semiconductor laser system with a plurality of semiconductor laser units comprising a laser oscillator, laser radiation exiting from each of these units, a light-conducting fiber associated with each semiconductor laser unit, a coupling element for coupling the laser radiation exiting from the respective semiconductor laser unit into the respective light-conducting fiber, and a fiber bundle comprising the fibers as light conductor system, a total laser radiation formed by the sum of the coherent laser radiation generated by the respective semiconductor laser units exiting from one end of the fiber bundle, this total laser radiation illuminating a target surface on an object to be irradiated during laser activity of all the semiconductor laser units, such that complex irradiation tasks can be performed with this system in a simple and as effective a manner as possible it is suggested that a control be provided for controlling the power of each individual semiconductor laser unit in a defi

Abstract: A self-light-emitting indicating apparatus including an enclosure formed by combining a pair of opposing semi-tubular bodies, each having first and second support members positioned at both ends; first and second panels fixed on the first and second support members respectively, at least one of the first and second panels having a plurality of through-holes and/or having a sign indicating portion; a plurality of optical fibers contained in a container portion defined by the enclosure and the first and second panels, each having one end inserted and fixed in one of the plurality of through-holes provided in at least one of the first and second panels, and a light emitting diode contained in the container portion, arranged adjacent to the other end of the plurality of optical fibers which are bundled and cut, and having an optical leakage preventing means.

Abstract: A compound optical waveguide device which is of a reduced size has an optical waveguide chip, a photodiode, and a laser diode. The optical waveguide chip has a substrate of LiNbO.sub.3, a Y-shaped optical waveguide, a phase modulator, and a polarizer. The substrate has an end face inclined at 70.degree. with respect to the optical axis of the Y-shaped optical waveguide. A photodiode is fixedly mounted on the substrate. A portion of light propagated through the Y-shaped optical waveguide is reflected by the inclined end face to enter the photodiode. Light emitted from the laser diode enters the Y-shaped optical waveguide through the inclined end face.

Abstract: The present invention relates to a high capacity, high signal-to-noise ratio sensor incorporating an array of Bragg grating transducers photoinscribed on a dielectric guide and a feedback loop incorporating a wavelength selective element which is time modulated making it possible to obtain a laser sensor selectively switched by each Bragg grating.Application to monitoring strains or temperatures in a structure.

Abstract: A method of frequency stabilizing a semiconductor laser. The method includes the steps of detecting a heterodyne beat note by optically mixing a leakage field of an optical resonator and a frequency modulated output of the semiconductor laser and detecting a phase of the heterodyne beat note by mixing the heterodyne beat note in quadrature with a radio frequency reference signal. The method further includes the steps of filtering the detected phase of the heterodyne beat note, scaling the filtered detected phase of the heterodyne beat note, and modulating the semiconductor laser with the scaled detected phase of the heterodyne beat note and the radio frequency modulation reference signal.

Abstract: An optical waveguide for fiber-optic amplifiers is disclosed where the Progression of the fluorescence band of optical waveguides that are doped with erbium and aluminum can be additionally flattened if the core contains fluorine, e.g., in the form of ErF.sub.3 and AIF.sub.3, as an additional doping agent.

Abstract: A discharge excitation type pulse laser apparatus includes main discharge electrodes and and an auxiliary discharge electrode. In order to make a voltage pulse applied to the auxiliary discharge electrode rise up steeply without incurring any appreciable time lag, a reactor connected in series to a first charging capacitor is constituted by a first saturable reactor 19 with a second saturable reactor being additionally inserted in series to a second charging capacitor. After stray inductance and resistance components of a switch become minimum, inductance of the saturable reactor is first decreased, which is then followed by decreasing of inductance of the first saturable reactor. Degree of steepness of the voltage rise-up for corona and main discharges can set at high values, respectively, whereby preionization is accelerated to allow the main discharge to occur uniformly. The energy injected into the main discharge is increased. Laser output power and oscillation efficiency are enhanced.