Abstract: A frequency-converted laser may be made with a non-linear material having a surface coated with an anti-reflection coating by measuring an absorbance of the anti-refection coating, and using the non-linear crystal for frequency conversion in the laser if the absorbance measured is less than a rejection threshold of about 100 parts-per-million or less.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: Methods and apparatus for controlling a passively Q-switched laser (PQSL) that use a Q-switched laser as a voltage controlled oscillator (VCO) in a phase-locked loop control circuit are disclosed. The PQSL may be optically coupled to a detector. The detector may be coupled to a an input of a phase lock loop controller. A reference oscillator may be coupled to a reference input of the phase lock loop controller. An output of the phase lock loop controller may be coupled to an integrator. The integrator may be coupled to a means for controlling an amount of power provided to the PQSL.

Abstract: Methods and apparatus for aligning a lens with respect to an axis of beam propagation are disclosed. A position of the lens is adjusted with respect to the axis along one or more directions that lie substantially parallel to a surface of a bulkhead connector. The surface of the bulkhead connector is substantially not parallel to the axis of beam propagation. A position of the lens is adjusted along a direction substantially parallel to the axis of beam propagation. After adjustment, the position of the lens is fixed with respect to the surface. An example of a lens aligning apparatus includes a lens mount configured to receive the lens, a bulkhead connector having a surface, wherein the axis of beam propagation intersects a plane of the surface, means for fixing a position of the lens mount with respect to the surface; and means for fixing a position of the lens with respect to the lens mount.

Abstract: A laser apparatus is disclosed. The apparatus includes a Neodymium-doped lasing material having first and second surfaces and a passive Q-switch optically coupled to the second surface. The first-surface is substantially transparent to a pump radiation and substantially reflective to laser radiation generated by an interaction between the pump radiation and the Neodymium-doped lasing material. The laser radiation is characterized by a vacuum wavelength corresponding to an atomic transition from the 4F3/2 level to the 4I9/2 level of Neodymium in the lasing material. The second surface transmits at least a portion of the laser radiation. The lasing material and Q-switch are configured to produce pulses of the laser radiation characterized by a pulse length of greater than zero and less than about 1.5 nanoseconds and a pulse repetition rate greater than about 100 kHz. A PQSL laser, an apparatus for generating blue light and a display system based on the laser apparatus are also disclosed.

Abstract: The use of <100>-oriented crystals as gain media in lasers and optical amplifiers is disclosed. In a laser, a substantially <100>-oriented crystal, such as <100> YAG can be disposed within an optical cavity as a gain medium. The crystal is orientated such that a <100> plane is substantially perpendicular to a direction of beam propagation within the crystal. A pump source provides pumping energy to a pumped region of the crystal. The use of a substantially <100>-oriented crystal can reduce depolarization loss and thermal lens effects if an absorbed power of the pumping energy is less than or equal to about 1000 watts of pumping radiation and/or a cross-sectional overlap between a beam of radiation propagating through the crystal and the pumped region is greater than about 20% of a cross-sectional area of the pumped region.

Abstract: A heterodyne modulated optical signal that includes two or more beat notes is produced. A portion of the heterodyne modulated optical signal is coupled to a device under test (DUT). This portion includes modulation at least at two of the beat note frequencies. The output of the DUT includes signals corresponding to two of the beat notes. These signals are mixed to produce a mixed output signal having the same frequency as an additional beat note but a phase that depends on the phase response of the DUT at one or more of the two beat note frequencies. The phase of the mixed output signal is measured with respect to a reference signal having the same frequency and a known phase with respect to the additional beat note. The resulting phase measurement represents the dispersion of the DUT with respect to modulation frequency.

Abstract: A Saturable Reflector apparatus comprises a substrate having a first and second surfaces, and a reflector having a saturable absorber layer, attached to the first surface. At least one of the first and second surfaces has been modified to enhance an etalon effect of the substrate due to interference of light reflecting from the first and second surfaces. Either or both of the surfaces may be modified, for example, by polishing or coating. The apparatus may also include means for adjusting an optical thickness of the substrate to tune the etalon effect. Such means may comprise a temperature control element, such as a heater, coupled to a temperature controller. The inventive apparatus may be incorporated into a mode-locked laser. The etalon tuning optimizes a relation between temporal and frequency domains of radiation incident on the saturable reflector.

Abstract: Co-doping the gain medium of a diode-pumped infrared laser to make the laser resistant to long-term degradation from high-intensity internal infrared radiation is disclosed. Co-doping the gain medium with ions such as Cr3+ and Ce3+ that make the gain medium resistant to external ionizing radiation solves problems of long-term degradation of the gain medium.

Abstract: Methods and apparatus for calibrating a frequency difference between two or more lasers over an extended frequency range as well as optical signal generators that employ such an apparatus or method are disclosed. The lasers are tuned in coordination with respect to one or more readily characterized narrow frequency ranges to characterize one or more tuning parameters of each of the lasers over the extended frequency range. The apparatus may include first and second tuning controllers respectively coupled to the first and second lasers, an optical coupler optically coupled to the first laser and the second laser, a frequency detector coupled to the optical coupler and a controller coupled to the frequency detector and the temperature controllers. The controller may include a processor and a memory containing processor executable instructions for calibrating the two lasers in accordance with the method described above.

Abstract: A method for tuning nonlinear optical frequency converters including devices such as optical parametric amplifiers and optical parametric oscillators through degeneracy. The nonlinear conversion process is driven by a pump beam at an original pump wavelength and the tuning is accomplished by setting a passband around a first wavelength generated by the optical frequency converter and thereby generating a passband image around a second wavelength. Once the passband and passband image are within a critical range the original pump wavelength is adjusted to an adjusted pump wavelength and tuning continues by moving the passband which the adjusted pump wavelength is either held constant or further adjusted. In particular, the passband can now be moved through the resonant wavelength which corresponds to a point of degeneracy at the original pump wavelength.

Abstract: A light source is disclosed having a pulsed laser, a fiber amplifier optically coupled to the pulsed laser, and a nonlinear frequency converting element optically coupled to the fiber amplifier. The pulsed laser, e.g., a passively Q-switched laser, is configured to generate light pulses characterized by a pulse length of less than about 1.7 nsec and sufficiently large that a frequency bandwidth of the pulses after they emerge from the fiber amplifier is less than an acceptance bandwidth of the nonlinear frequency converting element. The laser is pulsed at a pulse repetition rate sufficiently large that the fiber amplifier does not spontaneously emit radiation between pulses. In such a source, the fiber amplifier is substantially free of stimulated Brillouin scattering and self-phase modulation may be held to a level that does not reduce conversion of infrared radiation to visible radiation. Such a light source can be combined with an image generator and a scanner in an image projection system.

Abstract: Methods and apparatus for aligning a lens with respect to an axis of beam propagation are disclosed. A position of the lens is adjusted with respect to the axis along one or more directions that lie substantially parallel to a surface of a bulkhead connector. The surface of the bulkhead connector is substantially not parallel to the axis of beam propagation. A position of the lens is adjusted along a direction substantially parallel to the axis of beam propagation. After adjustment, the position of the lens is fixed with respect to the surface. An example of a lens aligning apparatus includes a lens mount configured to receive the lens, a bulkhead connector having a surface, wherein the axis of beam propagation intersects a plane of the surface, means for fixing a position of the lens mount with respect to the surface; and means for fixing a position of the lens with respect to the lens mount.

Abstract: A heterodyne modulated optical signal that includes two or more beat notes is produced. A portion of the heterodyne modulated optical signal is coupled to a device under test (DUT). This portion includes modulation at least at two of the beat note frequencies. The output of the DUT includes signals corresponding to two of the beat notes. These signals are mixed to produce a mixed output signal having the same frequency as an additional beat note but a phase that depends on the phase response of the DUT at one or more of the two beat note frequencies. The phase of the mixed output signal is measured with respect to a reference signal having the same frequency and a known phase with respect to the additional beat note. The resulting phase measurement represents the dispersion of the DUT with respect to modulation frequency.

Abstract: An optical fourth-harmonic generation system includes a resonant cavity configured to support electromagnetic radiation of a fundamental frequency and a fourth-harmonic generator disposed within the resonant cavity produces electromagnetic radiation of a fourth-harmonic frequency by an interaction with radiation of the fundamental frequency. The fundamental radiation is characterized by a p polarization that is complementary to an s polarization that characterizes the fourth-harmonic radiation. The fourth-harmonic generator has an output facet oriented substantially at a Brewster's angle with respect to the fundamental radiation to separate the fundamental radiation from the fourth-harmonic radiation as they emerge from the output facet.

Abstract: Methods and apparatus for controlling a passively Q-switched laser (PQSL) that use a Q-switched laser as a voltage controlled oscillator (VCO) in a phase-locked loop control circuit are disclosed. The PQSL may be optically coupled to a detector. The detector may be coupled to a an input of a phase lock loop controller. A reference oscillator may be coupled to a reference input of the phase lock loop controller. An output of the phase lock loop controller may be coupled to an integrator. The integrator may be coupled to a means for controlling an amount of power provided to the PQSL.

Abstract: A pump resonant optical parametric oscillator (PROPO) is optimized for noise suppression of pump radiation of wavelength &lgr;p. The PROPO generally comprises a parametric amplifier disposed within a resonant cavity having input and output couplers. The parametric amplifier has a gain G that increases with increasing power at a pump wavelength &lgr;p. The cavity resonates at both pump wavelength &lgr;p and signal wavelength &lgr;s. The parametric amplifier transfers noise on the pump radiation to the signal radiation. Input coupler transmission TIC, output coupler pump transmission TP, signal transmission TS, and gain G are chosen such that a resonated pump power at &lgr;p is nearly clamped at a threshold level. By setting these parameters such that the PROPO has a threshold slightly lower than the available power at a wavelength of the optical pump, noise on the pump radiation may be reduced by greater than about a factor of 10.

Abstract: A precision positioning mount for UV-cured adhesives that provides adhesive junctions between modular assembly mounts and structural elements. Contact edges are placed on a first fixating area of an adhesive junction. The contact edges are pronounced edges of faces that slide along a second fixating area during the adjustment process. Thus, the assembly modules and structural elements are precisely referenced before, during and after their positioning and orientating. First and second fixating areas form a cavity that provides a volume for the adhesive. The mounts and structural elements are preferably made of sapphire for increased thermal conductivity. The elements of the assembly mounts are modular and interchangeable and provide various positioning modes.

Abstract: Pulse recovery times are reduced in a pulsed intracavity frequency-converted laser by operating the laser in a continuous-wave (c.w.) mode before operation in a Q-switched mode. C.w. light locally optically heats the frequency-conversion optics of the laser to facilitate phase-matching at the beginning of Q-switched operation. C.w. operation also reduces the amplitude of the first pulse of the subsequent firing sequence by expending population inversion accumulating in the gain medium. Operation in c.w. mode is initiated by ramping up the net optical gain in the laser cavity when the time elapsed since the latest emitted pulse exceeds 110% of the interpulse spacing prior to the latest pulse. Initiation of c.w. operation does not require external signals other than optionally a pulse trigger sequence from the user. Cavity optical losses may be increased immediately prior to the first pulse, for accumulating population inversion and increasing the first pulse to a desired level.

Abstract: A system and method for reducing pulse-to-pulse energy and peak power variation in various types of pulsed lasers, and in Q-switched lasers in particular. The system of invention has a laser cavity with a lasing medium pumped by a pumping device for delivering to the medium a pumping energy E.sub.pump. The system further includes a detection device and circuitry for determining the pulse magnitudes M.sub.i of laser pulses i, such as peak pulse amplitudes A.sub.i, pulse energies E.sub.i, pulse widths W.sub.i or other pulse metrics. According to the method of invention, a feedback mechanism which is in communication with the pumping device ensures pulse-to-pulse stability by increasing the pumping energy E.sub.pump when pulse magnitude M.sub.i of laser pulse i exceeds a mean pulse magnitude [M] and decreasing the pumping energy E.sub.pump when M.sub.i is less than [M]. Alternatively, the feedback mechanism is in communication with the switching device which controls that variable loss factor of the Q-switch.