Abstract: Described are methods of determining imbalance in an IQ modulator. Example methods include applying a set of at least three test signals to the I channel and Q channel to generate an output, then receiving output from a frequency measuring device coupled to the IQ modulator. Some of the set of test signals may be substantially different than other test signals in the set. After the frequency specific output is received, the method measures one or more values and derives the imbalance in the IQ modulator from the measured values. Embodiments also include adjusting parameters of the test signals until a minimum distance is measured. A device is also described, which includes a test signal generator, an output analyzer, and a minimizer structured to cause the test signal generator to generate a set of test signals that cause a distance measured in the output to be a minimum distance.

Abstract: Described are methods of determining imbalance in an IQ modulator. Example methods include applying a set of at least three test signals to the I channel and Q channel to generate an output, then receiving output from a frequency measuring device coupled to the IQ modulator. Some of the set of test signals may be substantially different than other test signals in the set. After the frequency specific output is received, the method measures one or more values and derives the imbalance in the IQ modulator from the measured values. Embodiments also include adjusting parameters of the test signals until a minimum distance is measured. A device is also described, which includes a test signal generator, an output analyzer, and a minimizer structured to cause the test signal generator to generate a set of test signals that cause a distance measured in the output to be a minimum distance.

Abstract: A high dynamic range receiver includes a detector that produces a current at a pair of terminals. A first gain element, implemented as a current-to-voltage converter for example, is coupled to the first terminal, receiving the current and generating a first output signal corresponding to the current. A second gain element, implemented as a current-to-voltage converter for example, is coupled to the second terminal, receiving the current and generating a second output signal corresponding to the received current. A switch selectively couples the first output signal or the second output signal to a port based on a comparison of at least one of the first output signal and the second output signal to a threshold.

Abstract: A high dynamic range receiver includes a detector that produces a current at a pair of terminals. A first gain element, implemented as a current-to-voltage converter for example, is coupled to the first terminal, receiving the current and generating a first output signal corresponding to the current. A second gain element, implemented as a current-to-voltage converter for example, is coupled to the second terminal, receiving the current and generating a second output signal corresponding to the received current. A switch selectively couples the first output signal or the second output signal to a port based on a comparison of at least one of the first output signal and the second output signal to a threshold.

Abstract: Measurement and correction of encoder errors in a servo loop. By driving the servo system on a predetermined trajectory such that encoder errors occur at frequencies outside the servo loop response, these errors are sampled. Sampled encoder error data is filtered to produce correction data, which may be applied inside or outside the servo loop.

Abstract: A zero calibration system and method for an optical receiver include an illuminated photodetector, switchably coupled to an amplifier. The photodetector is de-coupled from the amplifier while illumination of the photodetector is maintained and an error signal is measured at the output of the amplifier The photodetector is then coupled to the amplifier and subsequent signals measured at the output of the amplifier are corrected according to the measured error signal, based on a comparison of the relative values of a feedback resistor, coupled between the output and an input of the amplifier, and an equivalent resistance of the photodetector. When the ratio of the feedback resistor to the equivalent resistance does not exceed a predetermined threshold, the subsequently measured signals at the output of the amplifier are corrected by offsetting the subsequently measured signals by the measured error signal.

Abstract: A zero calibration system and method for an optical receiver include an illuminated photodetector, switchably coupled to an amplifier. The photodetector is de-coupled from the amplifier while illumination of the photodetector is maintained and an error signal is measured at the output of the amplifier The photodetector is then coupled to the amplifier and subsequent signals measured at the output of the amplifier are corrected according to the measured error signal, based on a comparison of the relative values of a feedback resistor, coupled between the output and an input of the amplifier, and an equivalent resistance of the photodetector. When the ratio of the feedback resistor to the equivalent resistance does not exceed a predetermined threshold, the subsequently measured signals at the output of the amplifier are corrected by offsetting the subsequently measured signals by the measured error signal.

Abstract: Improved calibration of optical wavelength measuring instruments. In a first embodiment, improved calibration is achieved in an optical wavelength measuring instrument by performing calibration measurements at a plurality of known wavelengths and using an average calibration constant derived from the plurality of measurements. In a second embodiment, improved calibration is achieved by performing calibration measurements at a plurality of known wavelengths and calculating a linear or higher order calibration model, or a periodic model. These approaches may be extended by segmenting the wavelength range and using different calculated calibration values, or different calibration models, for each segment.