Abstract: The invention is a semiconductor optical device and method of fabrication where the device includes an active region with an active layer having a first index of refraction, and a blocking region having a second, lower index of refraction. A semiconductor layer having an index of refraction higher than the blocking region formed over both the active and blocking regions so that the layer is in closer proximity to the active layer in areas not covered by the blocking region so as to decrease the difference between the effective index of refraction in the active region and the effective refractive index of the blocking region. Such devices are particularly useful for pumping optical amplifiers since greater power can be achieved while maintaining single mode emission.

Abstract: The invention is a semiconductor optical device and method of fabrication where the device includes an active region with an active layer having a first index of refraction, and a blocking region having a second, lower index of refraction. A semiconductor layer having an index of refraction higher than the blocking region is formed over both the active and blocking regions so that the semiconductor layer is in closer proximity to the active layer in areas not covered by the blocking region so as to decrease the difference between the effective index of refraction in the active region and the effective refractive index of the blocking region. Such devices are particularly useful for pumping optical amplifiers since greater power can be achieved while maintaining single mode emission.

Abstract: The present invention is directed to a large area single-mode (LASM) laser system that provides a laser having a wider gain region and thus a higher power output without introducing the second transverse mode into the optical signal. The laser system of the present invention also reduces the laser junction temperature, thereby improving the reliability of the laser and of laser systems constructed therefrom. The present invention also provides a stabilized spectrum in an optical signal by providing a means for feeding back from an external fiber grating to the laser only a single mode and a selective spectrum of an optical signal generated by the laser.

Abstract: The invention is an optical apparatus and method of fabrication wherein an optical device such as a semiconductor laser includes a grating and a waveguide optically coupled to the grating. At least a portion of the waveguide coupled to the grating has a width which varies along the length of the waveguide in such a manner as to broaden the spectral line width of light output from the device. The width can be varied according to linear, sinusoidal or saw-tooth functions. A broadened line width permits pumping of a Raman amplifier at a high power without inducing any significant Brillouin Scattering.

Abstract: A semiconductor laser having a single transverse mode operation. Optical power higher than that generated by conventional pump lasers is achieved by widening the gain medium without inducing the second transverse mode. This is accomplished by providing a small refractive index difference between active and blocking regions of the laser. The refractive index difference between the laser active region material and the laser blocking region material at the fundamental frequency is less than about 0.029.

Abstract: A semiconductor laser having a single transverse mode operation. Optical power higher than that generated by conventional pump lasers is achieved by widening the gain medium without inducing the second transverse mode. This is accomplished by providing a small refractive index difference between active and blocking regions of the laser. The refractive index difference between the laser active region material and the laser blocking region material at the fundamental frequency is less than about 0.029.

Abstract: A semiconductor laser having a single transverse mode operation. Optical power higher than that generated by conventional pump lasers is achieved by widening the gain medium without inducing the second transverse mode. This is accomplished by providing a small refractive index difference between active and blocking regions of the laser. The refractive index difference between the laser active region material and the laser blocking region material at the fundamental frequency is less than about 0.029.

Abstract: An optical laser module exhibits stabilized output power over a range of input bias current and temperatures by utilizing an external Bragg grating with an essentially flat response over the grating bandwidth. The flat response is provided by using a combination of separate external gratings, the gratings exhibit different center wavelengths, with a center wavelength separation of 0.5 nm considered to be optimal.

Abstract: A lens system defined along an X-Y-Z coordinate system transforms an elliptical optical beam defined as exhibiting a first, fast axis component and a second, slow axis component, into an essentially circular optical beam. A first and a second lens intercepts the elliptical beam and a cruciform cylindrical lens is disposed to intercept the output from the second lens. The cruciform cylindrical lens has a fast lens and a slow lens, the fast lens having a first, front cylindrical surface oriented along the X axis of the coordinate system for magnifying the first, fast axis component, the slow lens having a second, rear cylindrical surface oriented along the Y-axis of the coordinate system for magnifying the second, slow axis component, wherein the magnifications are determined to provide an essentially circular output beam, the cruciform cylindrical lens disposed such that the optical beam exiting the second lens impinges the first, front cylindrical surface.

Abstract: A fiber filter for use in an optical amplifier communication system is in the form of an optical fiber connected between a laser pump module and an amplifier. In one preferred embodiment, the optical fiber is configured to have a predetermined loop diameter to attenuate light in the signal band of the amplifier. The cutoff wavelength, the diameter of the loop, and the number of loops may also be selected to attenuate the signal light sufficiently in the signal band of the amplifier.

Abstract: An apparatus is disclosed for aligning optical beams from a source to a destination. The apparatus comprises a first pair of cylindrical lenses comprised of a first cylindrical lens and a second cylindrical lens. The first and second cylindrical lenses are adapted to slide up and down or back and forth along first and second line segments. The first and second line segments can be parallel to each other. A second pair of cylindrical lenses is disclosed comprised of a third cylindrical lens and a fourth cylindrical lens. The third and fourth cylindrical lens are adapted to slide up and down or back and forth along a third and fourth line segments. The first, second, third, and fourth line segments can be parallel to each other. The first, second, third, and fourth cylindrical lenses can adapted to slide between an optical source and an optical destination. The first and second cylindrical lenses, and the third and fourth lenses respectively can be closely adjacent one another.

Abstract: An apparatus which routes light generated by a light source to a remote destination. The apparatus includes a cylindrical optical element defining a longitudinal axis. The element has an end face which is oblique relative to the longitudinal axis. The end face routes light by refraction or reflection. A support having a support surface is provided for positioning the optical element between the source and the destination so that the longitudinal axis of the element is substantially parallel to the support surface. The support substantially prevents rotational movement of the optical element about an axis extending normal to the support surface while allowing rotational movement of the optical element about its longitudinal axis so that the direction of the light routed by the end face can be selectively and continuously changed as a function of the rotation of the optical element.

Abstract: A lens system for use with elliptical optical sources includes a spherical fiber lens disposed beyond a conventional confocal lens arrangement. The spherical fiber lens is disposed in the optical path at the point where the slow axis (X ray) crosses the fast axis (Y ray); the rays will be "circular" and will thereafter propagate as a circular wavefront. The coupling efficiency of such a system is thus improved from approximately 40% to over 80%. The radius of the spherical endface of the fiber lens may be adjusted to improve the coupling efficiency. The spherical fiber lens is easily formed by fusing a section of "coreless" silica fiber onto the endface of a conventional single mode fiber. The end of the silica fiber is thereafter prepared (by heating, etching, polishing, or laser machining, for example) to provide a spherical endface with the desired radius.

Abstract: A laser module uses series connected thermoelectric coolers to maintain lasers at the proper operating temperature. A variable resistance associated with the thermoelectric cooler is adjusted to maintain the current through the cooler at the proper value.

Abstract: A two dimensional semiconductor laser array comprises a heat conducting base plate. A plurality of laser bars, having laser diodes stacked adjacent each other, are disposed in between a plurality of heat spreader plates and over the heat conducting base plate. Two spaced apart sidewalls are disposed on the heat conducting base plate, such that the heat spreader plate is thermally connected to said two sidewalls. The laser bars and the heat spreader plates are stacked upon each other, such that each heat spreader plate is disposed in between two of the laser bars.

Abstract: A lenslet module configured to receive light from a two dimensional laser array having laser sources disposed in a plurality of rows and columns, comprises a transparent substrate that has a light-receiving surface and a light-emitting surface. A plurality of light-receiving lenslets are disposed on the light-receiving surface of the substrate, such that each lenslet corresponds to a laser source in the laser array. An emitting lens is disposed on the light-emitting side of the substrate, in order to focus light collected by the receiving lenslets at a given focal length located at a distance away from the emitting lens. The light receiving lenses and the light-emitting lens are preferably configured as plano-convex lenses.

Abstract: An optical subassembly comprises a two-dimensional semiconductor laser array having a plurality of laser diodes arranged in rows and columns. The laser diodes are configured to provide laser lights at a first and a second direction. A first lenslet module is disposed adjacent the semiconductor laser array, such that light emitted from the laser array in the first direction is collected by the lenslet module. The lenslet module is further configured to focus the collected light at a given first focal point that may be disposed on a receiving end of a fiber optic. A second lenslet module is disposed adjacent the semiconductor laser array, such that light emitted from the laser array in the second direction is collected by the second lenslet module. The second lenslet module is further configured to focus said collected light at a given second focal point disposed at the receiving end of a photodetector.

Abstract: A method of reducing undulation in the L vs. I curve of a laser which uses a fiber grating is presented. The spectral width of the fiber grating is made larger than the Fabry-Perot spacing of the laser cavity. As a result, as the laser shifts between harmonics due to laser functioning (e.g., laser drive current, laser aging, temperature change, or mechanical stress), the fiber grating is able to respond linearly because of a large spectral width.

Abstract: Semiconductor lasers are susceptible to harmful high currents or high voltage electrical transients. Semiconductor pump lasers are especially vulnerable to electrical transients under normal operation because of the large continuous wave current needed to drive the semiconductor pump laser to achieve a high optical power. A protection circuit for 980 nm pump lasers using a non-linear voltage-dependent resistance means which limits drive current based on a drive voltage powering a laser diode is demonstrated to be effective in guarding the laser against harmful electrical transients.