Abstract: A mask for Poisson spot suppression includes a plurality of petals equally spaced in a circular pattern, the petals comprising a gray scale lithography substrate, the substrate having an opaque center portion and a gradient of increasing transparency extending toward a perimeter of the circular pattern, the gradient effected by a gray scale lithography process.

Abstract: Aspects of the present disclosure involve a system and method for suppressing a Poisson spot. A Poisson spot is a bright spot in the geometrical shadow of circular/spherical shapes. A broad class of telescopes that involve simultaneous transmit and receive require suppression of the reflected light from the secondary mirror on the detector. In one embodiment, coronagraphy petal-shaped masks are fabricated using photolithography and wire-EDM for the suppression of the Poisson spot. The petal-shaped masks can be designed and fabricated to operate at varying Fresnel numbers and petal tip radius-of-curvature (ROC).

Abstract: Disclosed herein is a system for an apodization mask composed of multi-walled carbon nanotubes (MWCNTs) for absorbing unwanted stray light. An apodization mask is a precise pattern or shape that is mathematically derived using light scattering measurement techniques to achieve optimal light absorption. Also disclosed herein is an apparatus for a duplex telescope with stray light suppressing capabilities comprising: a primary mirror for transmitting and receiving light; a secondary mirror for defocusing transmitted light onto the primary mirror and for focusing received light; a photodetector which receives light; a laser transmitter which transmits light; and an apodization mask for absorbing stray transmitted light.

Abstract: An optical device including dynamic channel equalization is provided. In an exemplary multiplexer or line amplifier configuration the device includes a plurality of separate optical paths, each of which receiving a separate group of optical signals. Each group of optical signals is provided to an associated variable optical attenuator. Separate inputs of an optical combiner are each coupled to an output of an associated one of the variable optical attenuators. The optical combiner has an output providing the separate groups of optical signals in an aggregated form on an aggregate optical signal path. An optical performance monitor is coupled to the aggregate optical signal path, and is configured to detect an optical signal to noise ratio of each of the separate groups. The monitor supplied a feedback signal to corresponding ones of the variable optical attenuators for adjusting a respective attenuation associated with each of the attenuators in dependence of the detected optical signal to noise ratios.

Abstract: An optical device including dynamic channel equalization is provided. In an exemplary multiplexer or line amplifier configuration the device includes a plurality of separate optical paths, each of which receiving a separate group of optical signals. Each group of optical signals is provided to an associated variable optical attenuator. Separate inputs of an optical combiner are each coupled to an output of an associated one of the variable optical attenuators. The optical combiner has an output providing the separate groups of optical signals in an aggregated form on an aggregate optical signal path. An optical performance monitor is coupled to the aggregate optical signal path, and is configured to detect an optical signal to noise ratio of each of the separate groups. The monitor supplied a feedback signal to corresponding ones of the variable optical attenuators for adjusting a respective attenuation associated with each of the attenuators in dependence of the detected optical signal to noise ratios.

Abstract: An optical device including dynamic channel equalization is provided. In an exemplary multiplexer or line amplifier configuration the device includes a plurality of separate optical paths, each of which receiving a separate group of optical signals. Each group of optical signals is provided to an associated variable optical attenuator. Separate inputs of an optical combiner are each coupled to an output of an associated one of the variable optical attenuators. The optical combiner has an output providing the separate groups of optical signals in an aggregated form on an aggregate optical signal path. An optical performance monitor is coupled to the aggregate optical signal path, and is configured to detect an optical signal power of each of the separate groups. The monitor supplies a feedback signal to corresponding ones of the variable optical attenuators for adjusting a respective attenuation associated with each of the attenuators in dependence of the detected optical signal powers.

Abstract: An apparatus and method are provided for monitoring the Q-factor of a plurality of main signals that are simultaneously transmitted across a fiber optic line using wave division multiplexing. In particular, the includes an optical tap, a tunable optical bandpass filter, and a Q-detection circuit. The optical tap operates to tap the fiber optic line to provide a plurality of tapped signals corresponding to the plurality of main signals. The tunable optical bandpass filter acts to select one of the plurality of tapped signals, by only passing a selected signal in a chosen channel frequency band. The Q-detection circuit then determines the Q-factor of the selected signal. This operation can be performed sequentially for each of the plurality of tapped signals to provide a measure of the Q-factor for each of the plurality of main signals. This operation can also be continually repeated to provide a constant measurement of the Q-factor of each of the plurality of main signals.

Abstract: A testing circuit is provided for determining the Q-factor of an optical communication system. In the testing circuit, a variable attenuator attenuates a received optical signal in response to an attenuator control signal. A first optical-to-electrical converter converts a first portion of the attenuated optical signal into an electrical data signal. A second optical-to-electrical converter converts a second portion of the attenuated optical signal into a first power indication signal. A decision circuit detects high and low data bits in the electrical data signal based on a plurality of threshold voltage signals, and provides decision signals indicative of the results of these determinations. An error monitoring circuit receives the decision signals, determines the bit error rate of the incoming optical signal for the plurality of threshold voltages, and provides bit error rate signals.