Abstract: A high power, diode pumped laser has a Nd:YVO4 gain media. Scaling to higher powers is achieved with the use of a low doped gain media, increasing the length of the gain media as well as increasing the pump volume. Passive cooling is extended to output powers of 10 W or greater .

Abstract: The present invention is a system and method for mode-locking a laser, comprising reversibly converting radiation in the laser at a fundamental frequency into radiation at a second harmonic frequency, discriminating the radiation at the fundamental frequency using a polarization of the radiation at the fundamental frequency, and reconverting the radiation at the second harmonic frequency into radiation at the fundamental frequency.

Abstract: A synchronously pumped optical parametric oscillator (OPO) using a temperature tuned 90 degree phase matched LBO crystal is disclosed which provides a broad selection of output wavelengths. In one embodiment a Ti:sapphire pump source having a cavity length matched to the OPO cavity length pumps a cavity with an LBO crystal located at the cavity waist of the cavity mode. Resources are included to, tune the OPO to a desired wavelength, repetitively scan through a series of desired wavelengths, and adjust the cavity length to obtain a synchronous pumping condition and diagnose a wavelength at which the OPO is operating. A frequency doubled beam in the LBO crystal is generated as a substantially collinear alignment beam.

Abstract: A laser system has a high reflector and an output coupler defining a laser cavity with an optical axis. Included is a pump source, a mode-locking apparatus and at least one fold mirror positioned in the laser cavity along the optical axis. A gain media is positioned adjacent to the fold mirror. The gain media has an overlap region where an intracavity beam entering the gain media substantially overlaps the intracavity beam exiting the gain media.

Abstract: A multi-axial mode frequency conversion system includes two resonators. At least two resonator mirrors define a first resonator cavity. A gain medium is positioned in the first resonator cavity. A pump source supplies energy to the gain medium. The first resonator cavity produces a first beam with a plurality of axial modes that are incident on a doubling crystal in the first resonator and produce a frequency doubled output beam. The first resonator cavity provides a sufficient number of axial modes to oscillate so that the doubled output beam has a noise of less than 3% RMS. At least two resonator mirrors define a second resonator cavity coupled to the output beam from the first resonator cavity. The second resonator is configured to provide resonant enhancement of at least a portion of the plurality of axial modes. A non-linear optical material is positioned in the second resonator and configured to produce a harmonic output beam.

Abstract: A synchronously pumped optical parametric oscillator (OPO) using a temperature-tuned 90.degree. phase matched LBO crystal is disclosed which provides a broad selection of output wavelengths. A Ti:Sapphire pump source having a cavity length matched to the OPO cavity length pumps a cavity with an LBO crystal located at the cavity waist of the cavity mode.

Abstract: A mode locked pulsed laser incorporates an intracavity element to compensate for the dispersion caused by other intracavity elements. This element reduces the tendency of the pulse to broaden in the cavity due to group velocity dispersion and results in very short pulses. In the laser of the present invention, mode locking is initiated by detecting the beat frequency between adjacent longitudinal modes using a high speed photodiode. This signal is amplified and then the frequency is divided by two. The signal is passed through an electronically adjustable phase shifter and then to a power amplifier. This signal is applied to the acousto-optic modelocker. If the cavity length drifts the beat frequency between the longitudinal modes changes. The rf signal applied to the modulator changes in exactly the right manner to track the drift in cavity length. Thus the modelocker is automatically synched to the round trip of the laser cavity.

Abstract: A mode locked pulsed laser incorporates an intracavity element to compensate for the dispersion caused by other intracavity elements. This element reduces the tendency of the pulse to broaden in the cavity due to group velocity dispersion and results in very short pulses. In the laser of the present invention, mode locking is initiated by detecting the beat frequency between adjacent longitudinal modes using a high speed photodiode. This signal is amplified and then the frequency is divided by two. The signal is passed through an electronically adjustable phase shifter and then to a power amplifier. This signal is applied to the acousto-optic modelocker. If the cavity length drifts the beat frequency between the longitudinal modes changes. The rf signal applied to the modulator changes in exactly the right manner to track the drift in cavity length. Thus the modelocker is automatically synched to the round trip of the laser cavity.

Abstract: An improved dye laser having a birefringent tuning filter comprised of one or more birefringent plates wherein each plate is oriented at Brewster's angle to the resonant light beam and is an integer multiple of the thickness of the thickness of the first plate characterized by the fact that the thickness of the first plate is chosen using a new tuning relationship so that a single order tuning curve covers a tuning range of interest. This single tuning curve is almost linear throughout the tuning range and has a tuning angle at the center of the range of approximately five degrees. Also, the tuning curve has a slope throughout the tuning range which provides sensitivity of selected wavelength to tuning angle which is neither too great nor too small. A further refinement in the structure is a non-birefringent polarizing plate at Brewster's angle which increases the losses imposed upon light passing therethrough which is polarized at other than Brewster's angle.

Abstract: A mode-locked fiber laser having a length greater than 10 meters is equipped with an intracavity shutter or "mode-locking" device. The intracavity shutter is a broad bandwidth modulator which allows fast shutter on and off speeds, allowing short on times as well as short on-off and off-on transition times. The fiber and the modulator may be integrated. The fiber is comprised of a material doped with an active species having a long lifetime upper state, wherein the upper state lifetime is longer than the round trip time of a pulse through the fiber. The laser may be configured as either a linear laser or a ring cavity laser. The present invention allows short pulse widths with high pulse energies.

Abstract: A solid state laser including a block of Nd:YVO.sub.2, Nd:YSAG, or Nd:YAB laser material having a cavity-defining mirror at one of its end surfaces is pumped by a laser diode pumping source having narrow bandwidth and is caused to lase in a single longitudinal mode by controlling the relationship between the pump power, the bandwidth of the lasing transition within the laser material, and the absorption depth of the pump radiation within the laser material.

Abstract: A KTP crystal in a nonlinear optical device is heated to and operated at a temperature of at least 50.degree. C. and less than 350.degree. C., and more preferably about 90.degree. C. to about 200.degree. C., and most preferably to about 100.degree. C. to about 125.degree. C., to reduce drift and damage. The KTP crystal is placed in an oven or other heating device, which may be regulated or unregulated. The KTP may be cut at the room temperature phase matching angle and angle tuned for operation at the higher temperature, or the KTP may be cut at the correct angle for phase matching at the operating temperature.

Abstract: An optical fiber for use in a pulse compressor which compresses a relatively long width optical pulse to a short width pulse, has a V number between 2 and 2.405 and a .DELTA. of less than 0.3%. In another aspect of the present invention the optimum length of an optical fiber which may be used to generate self phase modulation in a pulse compression apparatus is selected by successively cutting off fixed lengths of the fiber and measuring the optical energy of a pulse from which the Raman band has been separated. When the optical energy no longer increases, the fiber length has been optimized.

Abstract: Fluctuations in input intensity and pulsewidth affect the frequency doubled output pulse of a fiber grating optical pulse compressor in a compressed, continuous-wave, mode-locked Nd:YAG laser system. An optimized intensity servo system greatly reduces these fluctuations and results in as much as 50 dB noise reduction at low frequencies. Fluctuations in either input intensity or pulsewidth are corrected by changing the input intensity by means of the servo system.

Abstract: A miniaturized Q-switch is added to the resonant cavity of a compact laser diode pumped solid state laser to produce short high peak power pulses which are input into a single mode optical fiber to form a compact continuum generator. Q-switching the compact laser diode pumped solid state lasers takes advantage of the relatively high gain and short cavity length to provide a desirable combination of pulsewidth and pulse energy. Nd:YAG or Nd:YLF are useful solid state laser materials for Q-switching, or other longer lifetime rare earth ions such as erbium or holmium for greater energy storage. The Q-switch is formed of a material such as TeO.sub.2, SF.sub.10, or LiNbO.sub.3 with an acoustooptic figure of merit substantially greater tha fused silica. The high peak powers of the lasers are sufficient to exceed the threshold for Raman conversion in the fiber which produces a series of red shifted bands ending in a continuum by stimulated Raman scattering.

Abstract: A fiber laser for producing subpicosecond pulses is formed by placing a laser fiber in a resonant cavity, in either a linear or closed loop configuration. The laser fiber is formed of two different types of fibers joined in series, a gain fiber which contains the laser gain medium followed by a pulse shaping fiber which uses the phenomenon of solution pulse shaping to shorten the pulses. An initially formed pulse recirculates many times in the resonator; on each pass the pulse is both amplified and shortened until steady state is reached. The zero dispersion wavelength of the pulse shaping fiber is chosen to be slightly less than the laser wavelength. The fiber is pumped by a continuous source, particularly CW laser diodes. The initial pulse can be formed by a self starting technique produced by selecting the proper length of the laser fiber, or else a mode locker/acousto-optic shutter can be placed in the cavity.

Abstract: A fiber laser having a single mode fiber core of laser material is pumped by a high power coherent laser diode source by providing a multi-mode fiber around the single mode core to define a pump cavity which propagates pump radiation while allowing the pump radiation to couple to the single mode core. Laser diode arrays and extended emitter laser diodes can be used to pump a single mode fiber by inputting the pump radiation into the multi-mode fiber surrounding the single mode fiber core. The milti-mode fiber has a much greater diameter than the single mode core.

Abstract: A pulse compressor compresses a relatively long width optical pulse (of the kind which may be transform limited) to a short width pulse. The compressor includes a color generator which broadens the bandwidth of the long pulse to include any additional colors required for compression to the short pulse. The compressor also includes a grating which has a groove spacing and which is aligned with the output of the color generator at a grazing incidence angle effective for producing a compact grating structure, reduced ellipticity of the beam output from the compressor and high efficiency of light transmission through the device.

Abstract: A dispersion compensation delay line is added to a synchronously pumped fiber Raman ring oscillator to generate subpicosecond pulses. A pair of spaced gratings form the delay line. An interference filter is used as a bandwidth limiting tuning element to provide a good quality short pulse. An integrated design eliminates the discrete optical elements by using only an optical fiber and an optical fiber coupler.

Abstract: The output of a continuous wave modelocked Nd:YAG laser is first pulse compressed and then frequency doubled from infrared to green, to provide a new pumping source for a synchronously pumped dye laser. The disclosed apparatus and methods can achieve tunable subpicosecond pulses at relatively high average power, over 300 milliwatts. The 1064 nanometer output of the pulse compressor is frequency doubled to 532 nanometers so as to provide 3.5 picosecond pump pulses at 82 MHz and average power exceeding one watt. When this is used to pump a Rhodamine 6G dye laser, tunable pulses as short as 190 femtoseconds output can be obtained from the dye laser, with average power over 300 milliwatts. With the addition of a cavity dumper, tunable subpicosecond pulses of 80 kilowatt peak power have been generated.