Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: A light frequency locker (10) able to accept a light beam (14) generated by a controllable light source (12) into a light diverter (16) and impart to it a transverse displacement characteristic which can be detected in a light detection unit (20) connected to a processor (22). The processor (22) then controls the light source (12). Optionally, a light diverger (18) may be provided to enhance angular resolution. The light diverter (16) and the light diverger (18) may either transmit or reflect the light. The light diverter (16) may particularly include a diffraction grating (116, 156), Fabry-Perot interferometer (216), multiple slit plate (316), or an acousto-optical unit (416).

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: A molecular fluorine (F2) laser is provided wherein the gas mixture comprises molecular fluorine for generating a spectral emission including two or three closely spaced lines around 157 nm. An etalon provides line selection such that the output beam only includes one of these lines. The etalon may also serve to outcouple the beam and/or narrow the selected line. Alternatively, a prism provides the line selection and the etalon narrows the selected line. The etalon may be a resonator reflector which also selects a line, while another element outcouples the beam. The etalon plates comprise a material that is substantially transparent at 157 nm, such as CaF2, MgF2, LiF2, BaF2, LiF, SrF2, quartz and fluorine doped quartz. The etalon plates are separated by spacers comprising a material having a low thermal expansion constant, such as invar, zerodur®, ultra low expansion glass, and quartz.

Abstract: An excimer or molecular fluorine laser includes a gain medium surrounded by a resonator and including a line-narrowing module preferably including a prism beam expander and one or more etalons and/or a grating or grism within the resonator. The material of transmissive portions of the line-narrowing module including the prisms and the plates of the etalons comprises a material having an absorption coefficient of less than 5×1031 3/cm at 248 nm incident radiation, less than 10×10−3/cm at 193 nm incident radiation, and less than 0.1/cm at 157 nm. Preferably the material also has a thermal conductivity greater than 2.0 W/m° C.

Abstract: An excimer or molecular fluorine laser includes a discharge chamber filled with a gas mixture, multiple electrodes within the discharge chamber connected to a power supply circuit for energizing the gas mixture, and a resonator including the discharge chamber and a pair of resonator reflectors for generating an output laser beam. One of the resonator reflectors is an output coupling interferometer including a pair of opposing reflecting surfaces tuned to produce a reflectivity maximum at a selected wavelength for narrowing a linewidth of the output laser beam. One of the pair of opposing reflecting surfaces is configured such that the opposing reflecting surfaces of the interferometer have a varying optical distance therebetween over an incident beam cross-section which serves to suppress outer portions of the reflectivity maximum to reduce spectral purity.

Abstract: A device for generating blue or green laser light by the use of a device comprising an infrared high power semiconductor laser or an infrared high power semiconductor laser bar or array, a diffractive optical device, and an optical device utilizing a non-linear crystal to generate the blue or green laser light. In one embodiment, the diffractive optical device comprises a volume holographic transmission grating and the optical device comprises a ring resonator. In another embodiment, the diffractive optical device comprises a reflective diffraction grating feedback mechanism and the optical device comprises a ring resonator. In another embodiment, the optical device comprises a parabolic or non-planar feedback mechanism and a ring resonator. In another embodiment, the diffractive optical feedback device, which can be in the form of digital/binary optics, is attached to the semiconductor laser source.

Abstract: An apparatus and method are provided for bandwidth narrowing of an excimer laser to &Dgr;&lgr;≈6 pm or less with high spectral purity and minimized output power loss. Output stability with respect to pulse energy, beam pointing, beam size and beam output location is also provided. The excimer laser includes an active laser medium for generating a spectral beam at an original wavelength, means for selecting and narrowing the broadband output spectrum of the excimer laser, a resonator having at least one highly reflecting surface, and an output coupler. Means for adapting a divergence of the resonating band within the resonator is further included in the apparatus of the invention. The divergence adapting causes the spectral purity to improve by between 20% and 50% and the output power to reduce by less than 10%. A method according to the invention includes selecting and aligning the divergence adapting means.

Abstract: A device for and a method of pulsing and amplifying a singlemode laser light for use in a pulse oscillation laser is disclosed. The device comprises a singlemode laser for generating the laser light of the singlemode, an optical resonator into which the outputted laser light is introduced from the singlemode laser, and a controller for controlling the length of resonator by changing the length of the optical resonator based on a control waveform signal, which is an asymmetrical triangular repeated waveform signal. The laser pulse light of the singlemode to which optical strength is amplified from the optical resonator, is outputted by changing the length of resonator.

Abstract: A molecular fluorine (F2) laser is provided wherein the gas mixture includes molecular fluorine for generating an emission spectrum including two or three closely spaced lines around 157 nm. An optical method and means are provided for selecting an emission line from among the plurality of closely spaced emission lines of the molecular fluorine laser gas volume and broadening the spectrum of said selected emission line. This approach of broadening the spectrum reduces the coherence length of the output beam. As a result, speckle may be reduced or avoided in microlithography applications.

Abstract: A narrow band molecular fluorine laser system includes an oscillator and an amplifier, wherein the oscillator produces a 157 nm beam having a linewidth less than 1 pm and the amplifier increases the power of the beam above a predetermined amount, such as more than one or several Watts. The oscillator includes a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas, electrodes within the discharge chamber connected to a discharge circuit for energizing the molecular fluorine, and a resonator including the discharge chamber for generating a laser beam having a wavelength around 157 nm. Line-narrowing optics are included intra- and/or extra-resonator for reducing the linewidth of the laser beam to less than 1 pm. The amplifier may be the same or a different discharge chamber, and optical and/or electronic delays may be used for timing pulses from the oscillator to reach the amplifier at a maximum in the discharge current of the amplifier.

Abstract: Key technologies have been developed in realizing single longitudinal mode CW operation with a regular standing-wave cavity for intracavity frequency doubling and intracavity frequency conversions, so as to produce all solid-state, true cw devices with operation over wide spectral ranges including green, blue and UV. In one method, a beam expander (23 or 41) is applied to render a large mode waist and an improved beam divergence so as to greatly reduce the insertion losses for intracavity optical elements (17, 18 or 44). In another method, when spatial hole burning effect is minimized by using a pump head (12) with a thin gain zone (2), then a low resolving-power spectral filter with low loss can be utilized. In addition, several novel optical multipass constructions, typically by use of total-internal-reflection, have also been devised for pumping laser chips, laser rods, laser slabs, and for the use of multipass optical amplifier and pumping fiber lasers.

Abstract: A technique for increasing the lifetime of optical components that are used in a laser for laser shock peening. The technique employs a properly sized iris or a gradient reflector within a laser oscillator to produce a single-transverse-mode laser beam. This technique eliminates hot spots that significantly reduce the lifetime of optical components. Utilization of the present invention can increase the lifetime of components by a factor of ten of their conventional lifetime.

Abstract: A wavelength selective laser system and associated method are provided that produce laser beams having wavelengths that are only slightly different, but that permit a composite return signal to be selectively processed in accordance with the wavelengths of the signals that comprise the composite return signal. The wavelength selective laser system includes first and second lasers for producing respective laser beams. Each of the first and second lasers define a nominal gain spectrum. However, the wavelength selective laser system also includes a magnetic field generator disposed about the second laser for altering the gain spectrum of the second laser such that the wavelengths of the laser beams produced by the first and second lasers differ by at least one part per million. As such, the first laser will emit signals having a first wavelength and the second laser will emit signals having a second wavelength.

Abstract: A waveguide (10) is provided having a two-dimensional optical wavelength Bragg grating (20) embedded within a semiconductor laser medium (16). More particularly, the waveguide (10) includes an active region (16) sandwiched between n-doped and p-doped cladding layers (14, 22). The two-dimensional Bragg grating (20) is formed in the active region (16). Upper and lower electrodes (24, 26) are defined on opposite sides of the cladding layers (14, 22) to complete the waveguide structure (10). The two-dimensional grating (20) provides simultaneous frequency selective feedback for mode control in both the longitudinal and lateral directions.

Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: A top surface emitting vertical cavity laser with enhanced power handling capacity. The laser provides a patterned top electrode for uniformly injecting applied current to the active area. The diameter of the electrode relative to the vertical distance between it and the active layer is reduced by patterning. The result is an improved laser with significant power output.

Abstract: A semiconductor tunable laser system includes a tunable Fabry-Perot cavity and a cavity length modulator, which controls an optical length of the cavity at least over a distance corresponding to the spacings between the longitudinal modes of the laser cavity. Thus, the tunable Fabry-Perot cavity allows the laser cavity to have gain at the desired wavelength of operation while the cavity length modulator tunes the cavity length such that a longitudinal cavity mode exists at the desired wavelength of operation. Also, in one embodiment, a wavelength locker system is further provides that has a differential wavelength filter, e.g., stepped etalon, and a multi-element detector, e.g., a quad-detector. The controller then modulators the Fabry-Perot cavity to control the wavelength in response to the signal received from the multi-element detector.

Abstract: An oscillator for isolating a transverse electromagnetic (TEM) zero—zero mode pulsed laser beam includes a laser pumping diode that is mounted on a base to induce a multi-mode laser beam from a lasing medium. As initially induced, the multi-mode laser beam is directed along a path and is characterized by a beating signal which has a frequency that is based on amplitude variations of laser pulses in the multi-mode laser beam. Electronics detect this beating signal and generates a responsive error signal. With closed loop control, the error signal is used to advance a straightedge toward the path of the multi-mode laser beam to remove transverse modes from the multi-mode laser beam with the straightedge. This advancement continues until the error signal is a null and the zero—zero mode pulsed laser beam is thereby isolated.

Abstract: In a second harmonic, single-mode laser having a resonator including a Cr-doped fluoride laser crystal, first and second wavelength-selecting elements and a nonlinear optical crystal between a pair of laser mirrors, a wavelength-selecting width of the first wavelength-selecting element is {fraction (1/30)} or less of that of the second wavelength-selecting element, the first wavelength-selecting element is provided with a reflection coating having a reflectivity of 10-30% to the oscillated laser beam, such that the wavelength selection width of the first wavelength-selecting element is 0.02-0.03 nm, a wavelength interval in the oscillation wavelength range of the first wavelength-selecting element is 0.8-1.3 nm, and a wavelength selection width of the second wavelength-selecting element is 1.0-1.6 nm.

Abstract: A semiconductor laser light source tunable in wavelength comprising: a semiconductor laser which has one facet having an antireflection coating; a tunable bandpass filter for transmitting a light having a specific wavelength from wavelength components of output light out of the one facet having the antireflection coating of the semiconductor laser; and a fiber grating member for receiving the transmitted light from the tunable band pass filter and for reflecting a light of the specific wavelength. Preferably, as the fiber grating member, a compound fiber bragg grating which comprises a plurality of fiber gratings connected in series, each of which receives transmitted light from the tunable band pass filter and reflects only an individual wavelength different from one another, is used.

Abstract: A laser generating apparatus has a plurality of laser resonators and control loops for generating frequency locking signals independently for the respective laser resonators. A control signal generation circuit is provided so as to be common to the control loops. Control signals generated by the control signal generation circuit by frequency division are supplied to the respective control loops, whereby the phases of the laser resonators are locked to each other.

Abstract: An apparatus and method are provided for bandwidth narrowing of an excimer laser to &Dgr;&lgr;≈6 pm or less with high spectral purity and minimized output power loss. Output stability with respect to pulse energy, beam pointing, beam size and beam output location is also provided. The excimer laser includes an active laser medium for generating a spectral beam at an original wavelength, means for selecting and narrowing the broadband output spectrum of the excimer laser, a resonator having at least one highly reflecting surface, and an output coupler. Means for adapting a divergence of the resonating band within the resonator is further included in the apparatus of the invention. The divergence adapting causes the spectral purity to improve by between 20% and 50% and the output power to reduce by less than 10%. A method according to the invention includes selecting and aligning the divergence adapting means.

Abstract: The present invention provides a continuously-tunable external cavity laser (ECL) with a compact form factor and precise tuning. A novel interference filter which may be used to tune the ECL provides an absence of mode-hopping and reduced feedback from both spurious interference and reflections in the external cavity. A novel tuning mechanism is disclosed which provides for mechanical FM tuning of a wide range ECL tuning elements such as: an interference filter, a diffraction element, and a retroreflector. A novel feedback circuit is disclosed which provides closed loop feedback for selecting output wavelength in a laser.

Abstract: A single longitudinal mode narrow linewidth and low threshold all fiber laser arrangement is disclosed, constructed from a ring cavity, a gain portion in the ring cavity, an input-output coupling interposed within the cavity and pumping means connected to the ring cavity and to the grating such that, upon actuation of the pumping means, the arrangement acts as a laser.

Abstract: A self-seeding laser comprises a slave oscillator cavity coupled to a Littman cavity that operates in a single longitudinal mode. The slave oscillator cavity comprises the following elements positioned in sequential order to provide a first beam path: an end mirror, a gain medium, a grating having a groove spacing, and an output mirror. The first beam path has an angle of incidence upon the grating, and light traveling along the first beam path is zeroth-order diffracted by the grating. A tuning mirror faces the grating, for reflecting light diffracted away from the first beam path by the grating. The tuning mirror establishes the Littman cavity. The gain medium is pumped by a pulsed pump beam. The pump beam activates a pump region within the gain medium, the pump region having a radius.

Abstract: A self-mixing sensor usable for remotely measuring speed, vibrations, range, and length is provided in a manner making the device practical for economic implementation while retaining accuracy. In one embodiment, the device is configured to avoid mode hopping, such as by providing for relatively high loss for all modes other than the desired mode. Preferably this is accomplished by utilizing laser types that have a high degree of side mode supression, such as DFB lasers or through active or passive control of the amount of light permitted to reenter the laser.

Abstract: A laser system includes a gain medium for providing and amplifying a laser beam within an optical resonator. According to the invention, the laser system actively provides a plurality of different optical modes for stabilizing the laser beam, preferably by forcing the laser beam to jump between different optical modes more frequent than environmental disturbances occur. Providing the plurality of different optical modes can be achieved e.g. by varying the phase of the laser beam and/or by varying the optical length of the optical resonator. The laser system can be employed in a gas monitoring system, e.g. for monitoring a respiration and/or anaesthetic gas, for providing a Raman spectrum of the gas to be monitored.

Abstract: A thermally stable etalon Fabry-Perot etalon and method for making such etalons is disclosed. Particularly, a re-entrant etalon having an etalon gap which may be several times thicker than the etalon riser is presented. The riser and a spacer have differing dimensions and are constructed of materials having different coefficients of thermal expansion such that as the spacer expands increasing the etalon gap the riser expands a corresponding amount to keep the etalon gap in a thermally stable equilibrium. It is required that the etalon gap be formed to a very high degree of precision. In a preferred method of fabrication etalon plates and risers are provided. The etalon plates and risers are manufactured to ordinary precision optical standards. The riser and etalon plate are kept in a spaced apart relationship by spacers. To increase etalon gap precision, the spacer thicknesses are adjusted to high degrees of precision using special coatings.

Abstract: Abstract of the Disclosure A solid-state laser apparatus has a solid-state laser medium inside a resonator. A pump light source such as a semiconductor laser apparatus generates pump light, and an optical system focuses the pump light on the solid-stated laser medium such that its distribution is not only inside but also at least in part outside the resonator mode in the solid-state laser medium, say, over more than 50% of the total length of the solid-state laser medium.

Abstract: Fiber Bragg grating coupled light sources can achieve tunable single-frequency (single axial and lateral spatial mode) operation by correcting for a quadratic phase variation in the lateral dimension using an aperture stop. The output of a quasi-monochromatic light source such as a Fabry Perot laser diode is astigmatic. As a consequence of the astigmatism, coupling geometries that accommodate the transverse numerical aperture of the laser are defocused in the lateral dimension, even for apsherical optics. The mismatch produces the quadratic phase variation in the feedback along the lateral axis at the facet of the laser that excites lateral modes of higher order than the TM00. Because the instability entails excitation of higher order lateral submodes, single frequency operation also is accomplished by using fiber Bragg gratings whose bandwidth is narrower than the submode spacing. This technique is particularly pertinent to the use of lensed fiber gratings in lieu of discrete coupling optics.

Abstract: A Fabry-Perot etalon filter for use as a telescope filter and method for making such etalons is disclosed. Particularly, an air-gap etalon having a first etalon plate and a second etalon plate being separated by a plurality of spacers. Said separation defining a gap. Said spacers being cut from a small area of a spacer substrate which has been formed to a high degree of uniformity. As a result, the spacers have a high degree of uniform flatness, parallelism, and thickness. By optically contacting the spacers to the etalon plates, the precision of the spacers is transferred to the etalon gap. For etalons where an obstructed central aperture is not critical, a centrally mounted spacer may be used to increase etalon gap uniformity across the entire surface of the etalon plates. Also, where a clear central aperture is needed, large peripherally mounted spacers may be used to establish high gap uniformity across the etalon. A method of constructing etalons is disclosed.

Abstract: A line narrowed ultraviolet laser having a line narrowing system which includes a grating and an all reflective beam expander. In a preferred embodiment, the beam expander consists of a relatively small circular cylindrical mirror and relatively larger elliptical cylindrical mirror and the grating is an eschelle grating mounted in a Littrow configuration.

Abstract: A compound planar waveguide comprising multiple confinement structures that provides independent containment of pump and laser radiation. The waveguide may be formed of multiple layers of laser-active and laser-inactive materials to provide step changes in refractive index. The planar waveguide may include a central laserable core layer substantially sandwiched by at least two non-laserable cladding layers to provide an interface between the inner surfaces of the cladding layers and the gain medium core to define a first waveguide by virtue of an index of refraction discontinuity for containing developed laser radiation, and wherein the outer surfaces of the cladding layers define a second waveguide by virtue of an index of refraction discontinuity for containing pump radiation within the waveguide. The second waveguide may be also defined by an interface formed between the cladding layers and additional non-laserable external layers which sandwich the cladding layers.

Abstract: A molecular fluorine (F.sub.2) laser is provided wherein the gas mixture comprises molecular fluorine for generating a spectral emission including two or three closely spaced lines around 157 nm. An etalon provides line selection such that the output beam only includes one of these lines. The etalon may also serve to outcouple the beam and/or narrow the selected line. Alternatively, a prism provides the line selection and the etalon narrows the selected line. The etalon may be a resonator reflector which also selects a line, while another element outcouples the beam. The etalon plates, preferably uncoated, comprise a material that is transparent at 157 nm, such as CaF.sub.2, MgF.sub.2, LiF.sub.2, BaF.sub.2, SrF.sub.2, quartz and fluorine doped quartz. The etalon plates are separated by spacers comprising a material having a low thermal expansion constant, such as invar, zerodur.RTM., ultra low expansion glass, and quartz. A gas such as helium or a solid such as CaF.sub.

Abstract: A relatively high average power optical laser utilizes a diode pumped multi-mode dual-clad fiber amplifier configured for double pass amplification to provide a relatively higher average power than single mode fiber amplifiers. In order to compensate for mode scrambling and depolarization from the multi-mode fiber amplifier, the output beam from the multi-mode fiber amplifier is applied to a vector phase conjugator after a single pass through the amplifier and reflected back into the amplifier. The vector phase conjugator conjugates the electric field amplitude, phase and polarization and reflects a conjugate wave back into the multi-mode fiber amplifier in a reverse direction. The propagation of the conjugate wave through the amplifier unscrambles mode mixing and restores the beam back to its original polarization state. A Faraday rotator and polarization beam splitter are used to outcouple an output beam after the second pass through the multi-mode fiber amplifier.

Abstract: A durable etalon based laser output coupler. The output coupler is especially useful for ultraviolet lasers such as an ArF excimer laser or an F.sub.2 laser. The principal elements of the etalon based output coupler are two prisms aligned so that a first surface of one of the two prisms is parallel to a first surface of the other prism. The first of the two prisms have a second surface forming an angle with a beam from a laser cavity equal to or approximately equal to Brewster's angle. The second of the two prisms has a second surface forming an angle with the coupler exit beam equal to or approximately equal to Brewster's angle. Preferably, the prisms are comprised of CaF.sub.2 and surrounded by nitrogen at about one atmosphere. Assuming the laser beam is at a wavelength of 193 nm (for ArF excimer laser), Brewster's angle is about 57 degrees and each of the first and second surfaces define an apex angle of about 34 degrees.

Abstract: This invention discloses an optical resonator (24) including at least one spiral optical element (44) operative to change the angular phase distribution of modes in the optical resonator (24), thereby to generally eliminate undesirable modes.

Abstract: An external cavity, single mode laser has a semiconductor gain medium, such as a diode laser, and a monolithic prism assembly positioned in an external resonant cavity having a length of 10 mm or less. The monolithic prism assembly includes a transparent substrate carrying a thin film Fabry-Perot interference filter on a face which is tilted to the path of travel of the laser light in the external cavity. Translation of the monolithic prism assembly including transversely to the optical axis provides continuous mode-hop-free tuning of the laser output wavelength. The Such optical devices can be economically mass produced in advantageously small size, having reproducible spectral performance properties held within tight tolerances. Significantly advantageous applications include dense wavelength division multiplexing systems requiring tightly spaced wavelength subranges for each of multiple channels. High wavelength stability against temperature and humidity changes, etc., can be achieved.

Abstract: The present invention provides an external cavity laser that has wide-range continuous tuning and is compatible with a compact, robust, inexpensive form factor. In an embodiment of the invention a tunable external cavity laser is disclosed. The laser includes a laser amplifier, a retroreflector, a first and second reflector and a translator. The retroreflector is located in a path of the beam provided by the laser amplifier. The first and second reflectors are positioned opposite one another and in the path of the beam between the laser amplifier and the retroreflector. The translator translates at least one of said first reflector and said second reflector to vary the separation between the reflectors along the path of the beam, thereby tuning the laser amplifier. In another embodiment of the invention a method for adjusting wavelength in an optical device is disclosed.

Abstract: A broadband wavelength-selectable laser includes a gain medium, an optical transmission filter, and an optical fiber with a reflective filter such as a series of fiber Bragg gratings (FBGs). The gain medium is preferably a semiconductor laser diode that generates broadband optical energy. The gain medium is optically connected to the optical transmission filter, such as a bandpass filter, a notch filter, or a periodic filter, which converts the broadband optical energy into filtered optical energy having wavelength bands of high transmissivity and wavelength bands of low transmissivity. The optical transmission filter is optically connected to the series of FBGs that reflects different wavelength bands of optical energy. Either the optical transmission filter or the FBGs are tunable over a wavelength range that includes the desired laser wavelengths.

Abstract: An optical light source signal generator comprising an optical amplification medium for generating amplified spontaneous emission (ASE), having forward and backward light propagating ports for outputting output and backward optical light respectively, a reflector for reflecting the backward propagating optical light back toward the backward light propagating port, and an optical light spectrum reshaper interposed between the reflector and the backward light propagating port for transmitting the reflected light to the backward light propagating port with a wavelength dependence having a reduced amplitude in a band coinciding with an undesired high gain band of the optical amplification medium.

Abstract: A hybrid tunable Bragg laser including a double heterostructure gain section, a Bragg reflector section optically coupled to said gain section, and an optical extension constructed to yield a plurality of longitudinal modes. Preferably, the optical section has a predetermined length and effective reflectivity adapted to yield the plurality of longitudinal modes.

Abstract: Stable operation of an ultra-compact modelocked fiber laser generating short optical pulses generally without use of any non-fiber, intra-cavity polarization-manipulating elements is obtained by employing a saturable absorber coupled to one end of a highly-birefringent fiber serving as the laser cavity. Once the laser is modelocked in one of the polarization axes of the highly-birefringent fiber, the degeneracy of the polarization axis is eliminated and cw oscillation along the other polarization axis is also prevented. Without a polarization-dependent loss in the cavity, the modelocked polarization axis is indeterminate, i.e., modelocking can occur on either of the polarization axes. However, the introduction of only a small polarization dependent loss is sufficient to ensure the reliable start-up of modelocking on only the low-loss axis.

Abstract: A nonlinear dielectric material is incorporated within a photonic crystal as a means of changing the refractive index of a defect. In this way, the resonant frequency can be easily adjusted, after fabrication, by external mechanisms (either optical or electronic). The ability to tune the frequency of a resonant mode is useful for constructing photonic integrated devices, thus the invention enables the use of a photonic-crystal microcavity for such purposes. In one embodiment there is provided a photonic crystal having a periodic dielectric structure, and a defect positioned within the structure to define a microcavity. The defect includes a nonlinear material and being adapted to have an induced variation in index of refraction so as to tune the resonant mode of the microcavity.

Abstract: A laser-diode-pumped solid state laser in which a solid state laser crystal is pumped by a light beam produced by a laser diode and which is not lower than 10 W in the internal power of the resonator includes a temperature control circuit which keeps the inside temperature of a resonator at a predetermined temperature and, a wavelength selector which is disposed in the resonator and selects one of a plurality of oscillation modes in the resonator, thereby making the laser oscillate in a single mode. The wavelength selector has characteristics such that the increase in temperature of the wavelength selector due to absorption of a laser beam is smaller than a value such that when the temperature of the wavelength selector changes by the value or more, the oscillation mode selected by the wavelength selector changes.

Abstract: A polarization control element for controlling the direction of polarization and the longitudinal mode of a laser is formed by cutting a birefringent crystal so that its light incident face and light emanating face are at an angle to the optical axis of the crystal and adjusting the thickness and the reflectivities of the faces of the crystal so that the crystal can function as a Fabry-Perot etalon. The thickness of the birefringent crystal is set so that the wavelengths selected by the birefringent crystal for two laser oscillation modes whose directions of polarization are normal to each other differ from each other.

Abstract: A line narrowed laser having a grating based line narrowing module, etalon-based line narrowing output coupler and a technique for tuning the laser. The etalon based output coupler is adjusted to preferentially reflect light at or near the spectral maximum produced by the grating. Substantial improvement in line narrowing results from the amplification in the laser resonance chamber of light at or near the grating spectral maximum which is preferentially reflected by the etalon based output coupler. Several preferred methods are disclosed for tuning the etalon based output coupler to match the wavelength selected by the grating based line narrowing module.

Abstract: A high powered solid-state laser apparatus that is small in size and low in cost. The solid-state laser apparatus includes a semiconductor laser, a laser crystal, an etalon element, a non-linear wavelength converting element, and an output mirror, which are used to reduce the number of the fundamental wave length mode pieces, thereby raising an efficiency of the Q-switch. Thus, an output power of the laser is increased.