Abstract: An optical signal power monitor and regulator comprises: a lasing semiconductor optical amplifier for receiving the optical signal and whose laser output is used to monitor a power level of the optical signal; a monitor circuit which receives the laser output and outputs a monitoring signal; a tunable element for receiving a version of the optical signal and whose level of amplification is adjustable and for outputting an amplified optical signal; and a regulator circuit for receiving the monitoring signal and adjusting the amplification of the tunable optical amplifier depending upon the monitoring signal. The tunable element may comprise a tunable gain-clamped semiconductor optical amplifier. Such an embodiment is capable of automatically regulating the tunable element such that a power level of the amplified optical signal is kept stable.

Abstract: A multi-stage lasing semiconductor optical amplifier (SOA) device amplifies an optical signal. The multi-stage SOA includes at least two SOA stages coupled in series. Each SOA stage includes a semiconductor gain medium and a laser cavity including the semiconductor gain medium. The medium is pumped above a lasing threshold for the laser cavity, which clamps the gain of the medium. An optical signal propagating through the medium is amplified by the gain-clamped medium. The SOA stages are characterized by a design parameter which varies from stage to stage. In a preferred embodiment, the design parameter includes a noise figure and a saturable power, with both parameters increasing as the optical signal propagates from stage to stage. As a result, the multi-stage SOA can achieve better noise performance and higher power outputs compared to comparable SOAs of constant noise figure and saturable power.

Abstract: A broadband semiconductor optical amplifier (SOA) device includes at least two gain-clamped SOAs having different spectral responses. The gain-clamped SOAs are coupled so that the broadband SOA device has a spectral response which is not attainable by any one of the gain-clamped SOAs. The gain-clamped SOAs may be coupled in different ways. For example, they may be coupled in parallel, in series, or in another different and/or more complex ways. In one implementation, the gain-clamped SOAs are vertically lasing semiconductor optical amplifiers.

Abstract: An optical amplifier module that is insensitive to polarization comprises a first fiber, a second fiber, a semiconductor optical amplifier (SOA), and a polarization dependent loss (PDL) unit. The first fiber provides for optical input to the SOA. The SOA amplifies the optical signal received and outputs the amplified signal. The output of the SOA is optically coupled to the PDL unit. The PDL unit provides polarization dependent loss and the loss is preferably selected to match the polarization dependent gain of the SOA such that when two are coupled there is no overall polarization dependence. The output of the PDL is optically coupled to the fiber for transmission output.

Abstract: A multi-stage lasing semiconductor optical amplifier (SOA) device amplifies an optical signal. The multi-stage SOA includes at least two SOA stages coupled in series. Each SOA stage includes a semiconductor gain medium and a laser cavity including the semiconductor gain medium. The medium is pumped above a lasing threshold for the laser cavity, which clamps the gain of the medium. An optical signal propagating through the medium is amplified by the gain-clamped medium. The SOA stages are characterized by a design parameter which varies from stage to stage. In a preferred embodiment, the design parameter includes a noise figure and a saturable power, with both parameters increasing as the optical signal propagates from stage to stage. As a result, the multi-stage SOA can achieve better noise performance and higher power outputs compared to comparable SOAs of constant noise figure and saturable power.

Abstract: A tunable-gain lasing semiconductor optical amplifier comprises a vertical-lasing semiconductor optical amplifier that includes a tunable region which allows the gain of the vertical-lasing semiconductor optical amplifier to be tuned. The tunable region comprises a region whose loss and/or phase may be tuned by adjusting a physical characteristic of the region. For example, the region may comprise a liquid crystal layer whose transmissivity may be adjusted by applying different voltages across the layer to adjust the reflectivity of a cavity mirror, or a cavity mirror whose reflectivity may be adjusted by ion implantation. In an alternative embodiment of this invention, the tunable-gain lasing semiconductor optical amplifier comprises a tunable loss element in series after the gain-clamped semiconductor optical amplifier.

Abstract: An optical amplifier module that is insensitive to polarization comprises a first fiber, a second fiber, a semiconductor optical amplifier (SOA), and a polarization dependent loss (PDL) unit. The first fiber provides for optical input to the SOA. The SOA amplifies the optical signal received and outputs the amplified signal. The output of the SOA is optically coupled to the PDL unit. The PDL unit provides polarization dependent loss and the loss is preferably selected to match the polarization dependent gain of the SOA such that when two are coupled there is no overall polarization dependence. The output of the PDL is optically coupled to the fiber for transmission output.

Abstract: An optical signal power monitor and regulator comprises: a lasing semiconductor optical amplifier for receiving the optical signal and whose laser output is used to monitor a power level of the optical signal; a monitor circuit which receives the laser output and outputs a monitoring signal; a tunable element for receiving a version of the optical signal and whose level of amplification is adjustable and for outputting an amplified optical signal; and a regulator circuit for receiving the monitoring signal and adjusting the amplification of the tunable optical amplifier depending upon the monitoring signal. The tunable element may comprise a tunable gain-clamped semiconductor optical amplifier. Such an embodiment is capable of automatically regulating the tunable element such that a power level of the amplified optical signal is kept stable.

Abstract: A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide.

Abstract: An optical amplifier module that is insensitive to polarization comprises a first fiber, a second fiber, a semiconductor optical amplifier (SOA), and a polarization dependent loss (PDL) unit. The first fiber provides for optical input to the SOA. The SOA amplifies the optical signal received and outputs the amplified signal. The output of the SOA is optically coupled to the unit. The PDL unit provides polarization dependent loss and the loss is preferably selected to match the polarization dependent gain of the SOA such that when two are coupled there is no overall polarization dependence. The output of the PDL is optically coupled to the fiber for transmission output.

Abstract: Fabricating mirrored vertical surfaces on semiconductor layered material grown by molecular beam epitaxy (MBE). Low energy chemically assisted ion beam etching (CAIBE) is employed to prepare mirrored vertical surfaces on MBE-grown III-V materials under unusually low concentrations of oxygen in evacuated etching atmospheres of chlorine and xenon ion beams. UV-stabilized smooth-surfaced photoresist materials contribute to highly vertical, high quality mirrored surfaces during the etching.

Abstract: A low-noise optical amplifier solves crosstalk problems in optical amplifiers by using an optical cavity oriented off-axis (e.g. perpendicular) to the direction of a signal amplified by the gain medium of the optical amplifier. Several devices are used to suppress parasitic lasing of these types of structures. The parasitic lasing causes the gain of these structures to be practically unusable. The lasing cavity is operated above threshold and the gain of the laser is clamped to overcome the losses of the cavity. Any increase in pumping causes the lasing power to increase. The clamping action of the gain greatly reduces crosstalk due to gain saturation for the amplified signal beam. It also reduces other nonlinearities associated with the gain medium such as four-wave mixing induced crosstalk. This clamping action can occur for a bandwidth defined by the speed of the laser cavity. The lasing field also reduces the response time of the gain medium.