Abstract: One embodiment of the invention uses an MSM photodetector for light that is transmitted over a free space medium. The MSM photodetector with its low capacitance enables high speed data transmission and large alignment tolerances.

Abstract: The present invention describes methods and apparatus for reliably assuring that correct mirror currents are selected during a channel switch to achieve the desired wavelength channel, based on feedback from either internal or external means combined with a mode map obtained at a time zero calibration.

Abstract: One embodiment of the invention uses an MSM photodetector that is coupled to a relatively large core optical waveguide, e.g. an HCS fiber or a plastic optical fiber (POF). The MSM photodetector with its low capacitance enables high speed data transmission using large core optical waveguides.

Abstract: A vertical resonator laser diode and a method for fabricating it are described. Electrical connecting contacts can be disposed on a common main surface of the laser diode, for example its light exit side. For this purpose, in the course of the fabrication method, a contact-making zone is produced by indiffusion of impurity atoms, by which zone that side of the pn junction which is remote from the main surface can be electrically conductively connected to the main surface and be provided with a corresponding connecting contact.

Abstract: A photonic device designed with an intermittent absorption profile along a waveguide. The absorption profile is divided into low-absorption and high-absorption segments that are distributed axially in order to decrease the maximum local temperature in the device. The distribution of low-absorption segments can be controlled through techniques such as proton implantation or selective-area quantum well intermixing. The lengths of low-absorption and high-absorption segments can be adjusted to optimize heat dissipation along the device length.

Abstract: A compensating electrical signal is applied to one or more sections of a laser to over-compensate for chirp from an external modulator employed for intensity modulation. The chirp of the laser is adjustable by design or electrical control.

Abstract: A method and an apparatus for shaping semiconductor surfaces, in which a semiconductor wafer with a surface to be shaped is clamped in-between two plates. In which case at least one plate has a negative form with respect to the desired form to be formed in a semiconductor surface and the semiconductor surface is pressed by the plates at an elevated temperature. The method can be used particularly advantageously for fabricating concave microlens structures in semiconductor surfaces.

Abstract: A tunable modulator includes an epitaxial structure formed on a substrate. The epitaxial structure includes a waveguide for light guiding, generally in form of a ridge, a trench for thermal insulation and an integrated heating element which, when a current is passed therethrough, heats the modulator and in turn changes the effective bandgap. This alters the wavelength that is best modulated resulting in a tunable modulator in accordance with the present invention. Literature [1] Beck Mason, Greg A. Fish, Steven P. DenBaars, Larry A. Coldren, “Widely Tunable Sampled Grating DBR Laser with Integrated Electroabsorption Modulator,” IEEE Photonics Technology Letters, vol. 11, no. 6 pp. Jun. 4-6, 1999 FIG. 4. [2] Lucent/Agere Application Note TN00008 on electro-absorption modulators (EML), May 2000.

Abstract: A multiple phase wavelength locker employs an etalon with multiple steps, the steps providing optical cavities having different optical lengths for use with multiple photodetectors, such that a resonance position of each etalon step is offset by a fraction of a resonance period. The stepped etalon can be employed to track the exact wavelength of a laser in a wavelength division multiplexing (WDM) system.

Abstract: The present invention describes methods and apparatus for reliably assuring that correct mirror currents are selected during a channel switch to achieve the desired wavelength channel, based on feedback from either internal or external means combined with a mode map obtained at a time zero calibration.

Abstract: A vertical-resonator-laser-diode and a method of manufacturing the same are disclosed. An active layer sequence for the production of laser-radiation is assembled between a first Bragg-reflector-layer-sequence and a second Bragg-reflector-layer-sequence. Each Bragg-reflector-layer-sequence has a plurality of mirror-pairs; the two Bragg-reflector-layer-sequences form a laser-resonator. The two Bragg-reflector-layer-sequences and the active layer-sequence are assembled between a first and a second electrical contact-layer. At least one of the two Bragg-reflector-layer-sequences is semitransparent for the laser-radiation. At least one light-absorbing layer is assembled with a given light-absorption either between the semitransparent Bragg-reflector-layer-sequence and the first electrical contact-layer, or on the light-outlet-side of the first electrical contact-layer.

Abstract: A vertical resonator structure with active layer and Bragg reflectors formed in a mesa and provided with an upper contact and a substrate contact. A bond pad for connection to a housing and the upper contact are parts of the same metallization layer that are directly adjacent to one another. For bundling current in the active layer, an aperture can be formed between oxidized regions of an AlGaAs layer. The oxidized regions have at least the dimensions of the bond pad which are for example, 90 &mgr;m and at least approximately 50 &mgr;m.

Abstract: A vertical resonator laser diode and a method for fabricating it are described. Electrical connecting contacts can be disposed on a common main surface of the laser diode, for example its light exit side. For this purpose, in the course of the fabrication method, a contact-making zone is produced by indiffusion of impurity atoms, by which zone that side of the pn junction which is remote from the main surface can be electrically conductively connected to the main surface and be provided with a corresponding connecting contact.

Abstract: A tunable modulator includes an epitaxial structure formed on a substrate. The epitaxial structure includes a waveguide for light guiding, generally in form of a ridge, a trench for thermal insulation and an integrated heating element which, when a current is passed therethrough, heats the modulator and in turn changes the effective bandgap. This alters the wavelength that is best modulated resulting in a tunable modulator in accordance with the present invention.

Abstract: A transmission device contains a plurality of laser transmitters that can be driven individually with a driving current and output optical signals and whose operating point is set via a respective bias current. Each bias current has an individual correction current impressed on it. The correction currents are dimensioned such that, for the same bias current, the laser transmitters have an identical or essentially more uniform average optical output power at the desired operating point.

Abstract: A vertical-resonator-laser-diode and a method of manufacturing the same are disclosed. An active layer sequence for the production of laser-radiation is assembled between a first Bragg-reflector-layer-sequence and a second Bragg-reflector-layer-sequence. Each Bragg-reflector-layer-sequence has a plurality of mirror-pairs; the two Bragg-reflector-layer-sequences form a laser-resonator. The two Bragg-reflector-layer-sequences and the active layer-sequence are assembled between a first and a second electrical contact-layer. At least one of the two Bragg-reflector-layer-sequences is semitransparent for the laser-radiation. At least one light-absorbing layer is assembled with a given light-absorption either between the semitransparent Bragg-reflector-layer-sequence and the first electrical contact-layer, or on the light-outlet-side of the first electrical contact-layer.

Abstract: A method and an apparatus for shaping semiconductor surfaces, in which a semiconductor wafer with a surface to be shaped is clamped in-between two plates. In which case at least one plate has a negative form with respect to the desired form to be formed in a semiconductor surface and the semiconductor surface is pressed by the plates at an elevated temperature. The method can be used particularly advantageously for fabricating concave microlens structures in semiconductor surfaces.

Abstract: A vertical resonator laser diode includes an active layer sequence for generating laser radiation, which is disposed between a first Bragg reflector layer sequence and a second Bragg reflector layer sequence, each having a plurality of mirror pairs. The two Bragg reflector layer sequences form a laser resonator. The two Bragg reflector layer sequences and the active layer sequence are disposed between a first electrical contact layer and a second electrical contact layer. One of the two Bragg reflector layer sequences is partially transmissive to the laser radiation generated in the active layer sequence. A light exit opening or aperture opening in the first electrical contact layer is substantially smaller than a pumped active region of the active layer sequence. A current aperture stop is provided in at least one mirror pair of one of the two Bragg reflector layer sequences. Therefore, substantially only the fundamental mode of the laser diode is emitted during operation.

Abstract: A vertical resonator structure with active layer and Bragg reflectors formed in a mesa and provided with an upper contact and a substrate contact. A bond pad for connection to a housing and the upper contact are parts of the same metallization layer that are directly adjacent to one another. For bundling current in the active layer, an aperture can be formed between oxidized regions of an AlGaAs layer. The oxidized regions have at least the dimensions of the bond pad which are for example, 90 &mgr;m and at least approximately 50 &mgr;m.

Abstract: A vertical resonator laser diode has an active layer sequence for generating a laser radiation, an electrical contact layer, and a current aperture formed of a plurality of aperture layers with current passage openings of different sizes. The sizes of the current passage openings of the aperture layers increase in a direction away from the active layer sequence toward the electrical contact layer. A method for producing a vertical resonator laser diode is also provided.