Abstract: A WDM optical signal is transmitted through a tunable optical filter and is polarization-nulled to find optical signal to noise ratio of individual WDM channels. The polarization nulling can be performed using a heuristic multipoint extrema search method, such as Nelder-Mead method. A plurality of checkpoints can be included in the search to verify the progress and to improve the overall robustness of a real-time polarization nulling.

Abstract: For an apparatus which communicates data of a number of virtual lanes over a number of physical lanes, where the number of virtual lanes is different than the number of physical lanes and where a mapping between the virtual lanes and the physical lanes is not fixed, a method is provided for ascertaining the mapping between the virtual lanes and the physical lanes. The method includes: applying an impairment to a communication capability of one of the physical lanes so as to increase bit errors for data communicated via said one physical lane; determining a test bit error rate for each of the plurality of virtual lanes while the impairment is applied to the communication capability of the one physical lane; and ascertaining from the test bit error rates which of the virtual lanes is/are mapped to the one physical lane whose communication capability was impaired.

Abstract: A controller for reducing a transient variation of gain of an optical amplifier is disclosed. The controller includes a control circuit adapted to generate an electrical signal mimicking optical gain transient variation upon an abrupt change in input loading conditions. The electrical signal is applied to a variable optical attenuator disposed downstream of the active optical fiber of the optical amplifier. The control circuit can be realized in a variety of ways, but preferably it includes a logarithmic amplifier and a high-pass filter sequentially connected. The logarithmic amplifier is connected to an input tap/photodetector, and the high-pass filter is connected to the variable optical attenuator.

Abstract: For an apparatus which communicates data of a number of virtual lanes over a number of physical lanes, where the number of virtual lanes is different than the number of physical lanes and where a mapping between the virtual lanes and the physical lanes is not fixed, a method is provided for ascertaining the mapping between the virtual lanes and the physical lanes. The method includes: applying an impairment to a communication capability of one of the physical lanes so as to increase bit errors for data communicated via said one physical lane; determining a test bit error rate for each of the plurality of virtual lanes while the impairment is applied to the communication capability of the one physical lane; and ascertaining from the test bit error rates which of the virtual lanes is/are mapped to the one physical lane whose communication capability was impaired.

Abstract: The invention relates to angle-limiting optical reflectors and optical dispersive devices such as optical spectrum analyzers using the same. The reflector has two reflective surfaces arranged in a two-dimensional corner reflector configuration for reflecting incident light back with a shift, and includes two prisms having a gap therebetween that is tilted to reflect unwanted light and transmit wanted light. A two-pass optical spectrum analyzer utilizes the reflector to block unwanted multi-pass modes that may otherwise exist and degrade the wavelength selectivity of the device.