Abstract: An optical transmitter may obtain suitable optical output waveform within a wide temperature range from a semiconductor laser diode with an APC free system. The optical transmitter may be composed of a semiconductor laser diode, a driver circuit operatively connected to the semiconductor laser diode for supplying a bias current and a pulse current corresponding to the level of an input signal to the semiconductor laser diode, a bias current controller operatively connected to the driver circuit for controlling the level of the bias current, a pulse current controller operatively connected to the driver circuit for controlling the level of the pulse current, and a duty variable circuit operatively connected to the driver circuit for setting the duty of the input signal to make the duty of an optical output from the semiconductor laser diode more than 100% at an initial adjustment.

Abstract: The submarine optical cable has a basic structure which does not prevent rising up. Therefore, the cable is provided with at least one additional element which has a specific weight that is selected to be greater than 2.1 g/cm.sup.3 and prevents the rising up of the cable.

Abstract: A laser wavelength control system (20) stabilizes laser output wavelength. The control system includes a reflector/filter device (40) upon which laser radiation is incident for yielding both a filtered-transmitted signal (FS) and a reflected signal (RS). A controller (45) uses both the filtered-transmitted signal (FS) and the reflected signal (RS) to generate a control signal (CS). The control signal is utilized by a temperature converter (100) to adjust laser output wavelength of the laser (22). In one embodiment, the reflector/filter device is an optical fiber grating. The wavelength control system facilitates construction of a modular optical multichannel transmission system (200).

Abstract: There is a phenomenon that, when an epitaxial growth is performed on an uneven surface, such as a periodical surface or grating surface, having surfaces with different surface indices, p- and n-type layer portions can be simultaneously formed depending on growth surface orientations if an impurity such as Si or group IV elements is used. In a gain-coupling distributed feedback laser of the present invention, that phenomenon is utilized, and a current restraint layer, which includes alternately-arranged p- and n-type layer portions, is formed in the vicinity of an active layer. Thus, current is unevenly injected into the active layer, and a periodical gain structure can be established. As a result, a distributed feedback structure is achieved, which performs a gain-coupling operation.

Abstract: The generation of ultrashort pulses with adjustable repetition rates from passively modelocked fiber lasers is demonstrated. By inserting semiconductor saturable absorbers with life-times of the order of 10 nsec into fiber lasers with cavity round-trip times of the order of 100 nsec, passive harmonic modelocking is obtained, leading to the stable generation of pulses at integer multiples of the fundamental cavity frequency. For polarization states that allow for optical limiting of the lasers, pulses are obtained in a frequency range between 20 and 500 MHz., where different repetition rates can be simply selected by changing the pump power level to the cavity. The pulse jitter within one cavity round-trip time is measured to be between 300 psec and 50 psec, where side bands in the frequency domain may be suppressed by up to 70 dB.

Abstract: A wavelength-conversion solid-state laser capable of generating a ultraviolet laser beam with high efficiency. The wavelength-conversion solid-state laser is made up of a phonon-based solid-state laser crystal, a semiconductor laser which emanates pump light to pump the phonon-based solid-state laser crystal, a laser resonator, a wavelength selection element which selects an oscillation wavelength, and a nonlinear optical crystal which generates a sum frequency of a solid-state laser beam, whose wavelength is selected by the wavelength-selection element, and the pump light. The phonon-based solid-state laser crystal is pumped with pump light emitted from the semiconductor laser, as a result of which a solid-state laser beam is emitted. A sum frequency of the solid-state laser beam and the pump beam is produced by enabling them to pass through the nonlinear optical crystal.

Abstract: A light pulse generator is disclosed comprising an optical main-loop, a pumped-light source, a delay optical fiber, and an optical switch controller. The optical main-loop circulates a light and includes a light mixer, a light isolator, an erbium-doped optical fiber, an optical switch, a light divider, and an optical fiber coupler. The pumped-light source generates a pumped-light and introduces the pumped-light into the optical main-loop through the light mixer. The terminals of the delay optical fiber are connected to the optical fiber coupler so as to form an optical sub-loop for spreading a pulse width of a light pulse circulating in the optical main-loop. The optical switch controller switches the optical switch to an ON-state. As a result, a positive feedback amplification is carried out in the optical main-loop and an output light pulse having a sufficiently long pulse width and sufficiently high power is picked up from the optical loop through the light divider.

Abstract: A switch for selectively coupling light from an input optical fiber to a selected one of a plurality of output optical fibers. The switch includes a first carriage having one end of the input optical fiber attached thereto and a second carriage having the output optical fibers attached thereto such that one end of each of the output optical fiber lies between first and second distances with respect to the end of the input optical fiber when the output optical fiber is aligned with the input optical fiber. A lens that is fixed with respect to the end of the input optical fiber images light leaving the input optical fiber onto a plane lying between the first and second distances from the end of the input optical fiber. In one embodiment of the present invention, an encoder is integrated into the first and second carriages. The encoder includes an encoding input optical fiber having one end attached to the first carriage, the encoding input optical fiber being a single mode optical fiber.

Abstract: An external optical system is simplified in construction so that a laser oscillation apparatus is low-priced and compact as a whole. On the side of one end portion (10A) of a return-type resonator (10), a laser beam is reflected by a polarizing mirror (147) to be incident upon a polarizing mirror (146) which is situated diagonally below the mirror (147), and is also reflected by a polarizing mirror (142) to be incident upon a polarizing mirror (141) which is situated diagonally above the mirror (142). Thus, at the one end portion (10A), the polarizing mirror (141) and the like are arranged so that optical axes cross each other. Since the emitted laser beam forms a linear polarized beam inclined at an angle of 45.degree. to a horizontal plane, as indicated by arrow (100), the laser beam can be subjected to circular polarization by using only one 1/4-wavelength mirror. Thus, the construction of the external optical system can be simplified.

Abstract: A wavelength-conversion laser capable of maintaining a single longitudinal mode even when the temperature of a resonator changes. The wavelength-conversion laser is made up of a solid-state laser crystal doped with Neodymium which is pumped by light, a nonlinear optical crystal disposed in a resonator for converting the wavelength of a solid-state laser bee emanated from the solid-state laser crystal, and an etalon disposed in the resonator for realizing a single longitudinal mode. The nonlinear optical crystal is a crystal, which effects type-I phase-matching, such as MgO:LiNbO.sub.3 crystal. Moreover, the nonlinear optical crystal possesses periodic domain reversals.

Abstract: A getter for immobilizing water and organic molecules which may be present as impurities in an enclosure for a high power laser. The getter is formulated from selected zeolite compositions having a pore or channel size suitable for immobilizing water and a size range of organic molecules up to about 40 microns. A binder is used to provide a getter having sufficient strength to allow use of the getter in a laser enclosure in a telecommunications application. The binder also provides a substantially dust free getter body to maintain the cleanliness of the interior of the laser enclosure. Getters which immobilize only organics or only water are contemplated.

Abstract: The present invention provides a laser diode-pumped solid-state laser resonator which can be scaled and pumped longitudinally including in a folded or zig-zag resonator cavity. The resonator employs opposed laser rod crystals paired with pump light diodes in a configuration which ensures good spatial overlap and can permit the simultaneous generation of one or more laser wavelengths. The resonator also has at one end thereof a total reflector, eg. a laser rod crystal or a mirror and at the other end thereof, a partial reflector i.e. a mirror, to resonate and amplify the laser beam in the system and outcouple a portion thereof as desired.

Abstract: The cooling of the outer surface of the rod or other solid active element of a solid state laser is improved by causing coolant to travel in a plurality of, preferably streamline, helical flows extending around this surface in contact with it. The respective longitudinal components of a pair of the helical flows preferably extend in opposite directions along the surface to improve the uniformity of cooling.

Abstract: A semiconductor laser apparatus comprises a semiconductor laser, a photodetector, first and second variable gain units, a controllable amplifying unit, a driving unit, and a compensation unit. A control signal is supplied to one of input terminals of each of the first and second variable gain units and an output signal of the photodetector is negative-fed back to the other of the input terminals of each of the first and second variable gain units. A varied gain of an error between the control signal and the output signal is output independently of each of the first and second variable gain units. The controllable amplifying unit amplifies the error signal from the first variable gain unit with desired frequency characteristics. The driving unit includes a plurality of driving elements connected in parallel and supplies a driving current to the semiconductor laser in accordance with a drive control signal from the controllable amplifying unit.

Abstract: An end connector for fiber optic transport cables. A cable clamp received within a passageway of a housing which receives the cable is provided to hold the cable in a secured position so as to resist rotational and longitudinal forces applied to the cable. Support coupling units are provided both internal and external the equipment which the cable is to be connected to. The coupling units allow the end connector to be coupled to and decoupled from the equipment without unnecessary rotation of the end connector and cable and without having to remove the cable from the end connector. Grounding components are provided for grounding conductive members associated with the cable so as to prevent damage due to voltage surges and to prevent RF signal leakage.

Abstract: A fiber laser 26 including a rare-earth doped fiber laser cavity 32 delimited by a pair of reflective elements 28,30, such as Bragg gratings, is tuned by compressing the cavity 32 and the gratings 28,30. Because an optical fiber is a much stronger under compression than in tension, the laser 26 is tunable over a much broader range than conventional tension/stretching techniques.

Abstract: Variable waveform output in surgical laser is achieved by controlling power into a solid-state laser cavity. A control circuit is used to coordinate pulse energy, pulse frequency, and pulsewidth into a solid-state laser cavity to achieve a user desired waveform output. An Insulated Gate Bipolar Transistor (IGBT) or similar solid-state transistor switching device under the direction of a control circuit is used to switch energy into the solid-state laser cavity thereby modulating the pulse frequency and pulsewidth. The pulse energy is varied by varying the charge across the capacitor bank which sends energy through the IGBT to the solid-state laser cavity. By having the ability to vary the laser's output pulse frequency, pulsewidth, and pulse energy, multiple tissue effects can be achieved using one solid-state laser cavity.

Abstract: The present invention is directed to providing an environmentally stable, ultra-short pulse source. Exemplary embodiments relate to passively modelocked ultra-short fiber lasers which are insensitive to temperature variations and which possess only negligible sensitivity to pressure variations. Further, exemplary embodiments can be implemented in a cost-effective manner which render them commercially practical in unlimited applications. Arbitrary fiber lengths (e.g., on the order of 1 millimeter to 1 kilometer, or greater) can be used to provide an ultra-short pulse with a cost-effective architecture which is commercially practical.

Abstract: Wing pumping a Tm.sup.3+ doped, end pumped solid state laser generates 2 .mu.m laser radiation at high average powers with high efficiency. Using laser diode arrays to end-pump the laser rod or slab in the wing of the Tm.sup.3+ absorption band near 785 nm results in 2-for-1 quantum efficiency in Tm.sup.3+ because high Tm.sup.3+ concentrations can be used. Wing pumping allows the thermal power generated in the rod or slab to be distributed over a large enough volume to make thermal management practical in the laser gain medium even at high average power operation. The approach is applicable to CW, Q-switched, and rep-pulsed free-laser operation.

Abstract: A rod lens or a cylindrical lens is disposed in front of a semiconductor laser to increase a divergence angle of a laser beam emitted from the semiconductor laser so as to form a substantially circular far field pattern. In another constitution, there is disposed in front of a semiconductor laser a composite lens having two cylindrical surfaces whose cylindrical axes are perpendicular to each other. The cylindrical surface on the side of the semiconductor laser is a convex surface and the other cylindrical surface is a convex or concave surface. In still another constitution, two semiconductor lasers emitting the same optical signal are arranged adjacent each other so that respective light emitting portions of two pn junction planes are located in the same plane and perpendicular to each other, and that laser beams form orthogonal spots at a single predetermined position.