Abstract: The present invention demodulates a FM, WM or AM optical input beam, amplifies the signal impressed on the beam, and then modulates without intervening electronics the signal amplitude of an output beam. The apparatus can be made from any semiconductor laser, including edge-emitting lasers and VCSELs. Light transmitted through the waveguide (the “control beam”) interacts with the carrier population of the laser, reducing the available gain and thereby the output intensity. The present invention has three key advantages: (i) a FM control beam produces an amplitude-modulated output beam from the main-laser, (ii) the amplitude of the AM beam depends directly on the differential gain ∂G/∂&ohgr;, and (iii) the apparatus and method provides gain for all LOGiC devices. The present invention works with available and future semiconductor lasers, including those emitting in the blue as well as those operating at 670, 850, 980, 1300, and 1500 nm.

Abstract: The Vertical-cavity-surface-emitting Lasers with Optical Gain Control (V-LOGIC) form a family of integrated optical smart pixels for interconnect and signal processing applications. V-LOGIC devices consist of Vertical Cavity Surface Emitting Lasers (VCSELs) and In-Plane Lasers. (IPL) with cross-coupled cavities. The devices can operate in a digital, an analog or a hybrid mode. The IPLs either fully quench or modulate the VCSEL depending on whether the device is used in the digital or analog mode. In the Hybrid mode, one IPL serves as an enable input while another one modulates the VCSEL. The V-LOGIC devices can operate significantly faster than modulated lasers since, for the quenching phenomena, (1) the VCSEL carrier population is essentially constant and (2) the quenching is all-optical and does not require intermediate drive electronics. The family of devices solve the leading outstanding problems in optical switching and interconnect technologies.

Abstract: A thermal lens spectrometer utilizes a continuously tunable optical parametric oscillator (OPO) to provide practical, easy-to-build, reliable spectrometer for measuring a wide variety of sample materials over a wide spectral range. A flow cell is placed in the path of the output beam from a tunable optical parametric oscillator, and material to be analyzed is placed in the cell. A laser probe beam is also directed into the cell coaxially with the OPO output beam. The OPO output beam acts as a pump, and the output probe beam from the cell is directed to an intensity sensor. The OPO is tuned over a selected frequency range, under computer control, for example, to produce an output probe beam having an intensity representing the spectral response of the material to be analyzed.

Abstract: A broadly tunable femtosecond optical parametric generator includes a cavity having a pumping section in which is located a nonlinear crystal selected from the group CTA and RTA, cut for noncritical phasematching. The plane of the optical x axis and or the optical y axis of the crystal is aligned with the axis of the pumping section. A Ti:S laser pumping beam is directed into the pumping section either collinearly or noncollinearly with the pumping section axis and impinges on the crystal to produce signal and idler beams. The laser is tunable to produce OPO output beams between about 1 and 4 .mu.m.

Abstract: A method and apparatus for protecting polished surfaces of optical crystals includes placing a thin film of index-matching liquid between the polished surface and an optical flat, and hermetically sealing the liquid in place.

Abstract: A Ti:sapphire-pumped intracavity-doubled optical parametric oscillator generates up to 240 mW of sub100 femtosecond pulses tunable in the visible. The OPO consists of a 1.5 mm thick KTP crystal configured in a linear or a ring cavity which is synchronously pumped by a self-mode-locked Ti:sapphire laser. Intracavity doubling of the OPO is accomplished by inserting a .beta.-barium borate crystal into an additional focus in the OPO cavity. Continuous tuning of the second harmonic signal from 580 to 657 nm is obtained, with a potential tuning range being approximately 500 to 800 nm.

Abstract: A self-mode-locked ring cavity laser incorporating a laser crystal such as Ti:Sapphire includes an external cavity for producing self-starting of mode-locked operation. The external cavity receives a portion of one of the continuous wave beams from the ring cavity modulates it, and retroreflects it back to the ring cavity to initiate mode-locked unidirectional operation. The unidirectional mode-locked operation is in a direction which decouples the external cavity.

Abstract: A broadly tunable femtosecond optical parametric oscillator (OPO) based on KTiOPO.sub.4 is externally pumped by a self-mode-locked Ti:sapphire laser. The laser is capable of continuous tuning from 1.2 micrometers to 1.37 micrometers in the signal branch and 1.8 to 2.15 micrometers in the idler branch, when using one set of OPO optics. Other optics expand the tuning range of the OPO from 1.0 micrometers to 2.75 micrometers, for example, by using three sets of mirrors and two different crystals. Without prisms in the OPO cavity, 215 mW of chirped pulses is generated in the signal branch, while 235 mW is generated in the idler branch. The total conversion efficiency, as measured by pump depletion, is 50%. With prisms in the cavity, nearly transform-limited pulses of 135 femtoseconds are generated, which can be shortened to 75 fs by increasing the output coupling.

Abstract: A continuous wave tunable femtosecond optical parametric oscillator includes an oscillator cavity including a pumping cavity. A nonlinear KTiOAsO.sub.4 crystal (KTA) is located in the pumping cavity and is pumped by a Ti:sapphire laser to produce output pulses having widths as short as 85 femtoseconds at wavelengths in the range 1.0 .mu.m to 5.0 .mu.m.

Abstract: A Ti:sapphire-pumped intracavity-doubled optical parametric oscillator generates up to 240 mW of sub100 femtosecond pulses tunable in the visible. The OPO consists of a 1.5 mm thick KTP crystal configured in a ring cavity which is synchronously pumped by a self-mode-locked Ti:sapphire laser. Intracavity doubling of the OPO is accomplished by inserting a .beta.-barium borate crystal into an additional focus in the OPO cavity. Continuous tuning of the second harmonic signal from 580 to 657 nm is obtained, with a potential tuning range being approximately 500 to 800 nm.

Abstract: Polarization self-modulation of a laser produces high-frequency optical modulation without the use of high-speed electronics. This is accomplished by inserting into a laser cavity a polarization converter, which rotates the polarization of the laser light periodically as the light passes through the converter as it circulates in the cavity. The frequency of the modulation is determined by the cavity length. In one configuration, a quarter-wave retardation plate is used as the intracavity polarization converter in a Fabry-Perot laser. In a second embodiment, the converter is an electro-optic crystal which acts as an electronically-controllable half-wave retardation plate.

Abstract: The operation of a .beta.-BaB.sub.2 O.sub.4 optical parametric oscillator is disclosed. The oscillator is tunable in the visible and near infrared. For example, a .beta.-BaB.sub.2 O.sub.4 crystal 10.5.times.10.5 nm.sup.2 .times.11.5 mm, cut at .theta.=30.degree. was pumped at 354.7 mm, and was tunable through 0.45-1.68 .mu.m, with a total energy conversion efficiency of 9.4%.

Abstract: A laser pulse generator utilizes intracavity doubling in an ultrathin beta barium metaborate crystal to produce femtosecond pulses in the ultrashort ultraviolet wavelength range. The generator includes a colliding-pulse passively mode-locked ring dye laser which propagates a pulsed beam of primary laser light in a cavity. The primary light beam has a repetition rate of 10.sup.8 Hz and a pulse width in the femtosecond range. The crystal is located in the cavity so that the primary beam strikes one crystal surface at Brewsters angle and propagates through the crystal at its phase-matching angle. The primary beam and its second harmonic are emitted from the opposite surface, the harmonic wave having the same repetition rate and substantially the same width as the primary beam, but one-half its wavelength.

Abstract: An optical parametric oscillator capable of operating in the 0.300 to 0.400 micrometer wavelength range is disclosed. The oscillator includes a cavity defined at its ends by a pair of cavity resonator mirrors. A nonlinear optical crystal is positioned on the optical axis of the cavity intermediate the mirrors and is rotatable about a crystalline axis to tune the oscillator. A pair of pump steering mirrors are mounted in the cavity, one mirror between each resonator mirror and the corresponding end of the crystal. A source of pumping energy supplies energetic light to the cavity, the pumping beam being directed into the cavity and onto a first steering mirror, thence through the crystal and to the second steering mirror which then directs the pumping beam out of the cavity. The pumping beam may be at a wavelength of 266 nm, for example, to produce an output wave from the oscillator within the range of interest.

Abstract: A tunable, singley-resonant optical parametric oscillator provides femtosecond light pulses in the infrared wavelength band. The oscillator includes an internally mounted thin crystal of KTiOPO.sub.4 which is synchronously pumped by femtosecond pulses from a colliding-pulse passively mode-locked dye laser. Rotation of the crystal varies the wavelength of the oscillator. Prisms within the oscillator cavity control group velocity dispersion to limit pulse width, and the oscillator as stabilized by a feedback network which varies the length of the cavity in response to spectral changes.

Abstract: A new optical parametric oscillator which employs a urea crystal is disclosed. The organic crystal makes the oscillator broadly tunable, so that the entire spectral range from the ultraviolet to the near infrared is accessible.The urea optical parametric oscillator is angle tunable, and has a high efficiency.

Abstract: This invention relates to growing single crystals of urea having increased dimensions on the 110-110 faces by physically restricting growth of the 111 faces of a seed crystal while precipitating urea from a saturated alcoholic solution containing ammonium bromide. In addition, this invention relates to a seed crystal holder adapted to modify crystal habit during crystal growth.

Abstract: An amplitude modulator for a tunable ring cavity dye laser is disclosed. The modulator is operated in time synchronization with the laser pump and is located assymetrically within the ring to attenuate dye laser pulses in one direction while passing pulses in the opposite direction, thereby producing a mode locked unidirectional travelling wave. The use of a low dispersion electro-optical modulator in a dye laser yields subpicosecond optical pulses with wide tunability.

Abstract: A method and apparatus is described which allows a cw dye laser to be tuned over hundreds of angstroms on a nanosecond time scale in spite of the relatively long cavity decay and build up time. A tuning element is positioned at the mid-point between the reflective mirrors that define the length of the cavity.

Abstract: A method of making optical gratings by the use of a Scanning Electron Microscope wherein (1) a substrate having a thin film of electron resist thereon is exposed in adjacent areas by an electron dosage and the amount of such dosage and the depth of the thin film are selected such that energy deposition in regions between adjacent exposed areas in said electron resist is below the threshold sensitivity of said resist for development, (2) the development time of the resist is made an inverse function of the electron dosage, and/or (3) the period of the grating is controlled by use of a standard scanning format.