Abstract: A test and measurement system is disclosed. The system includes a data store with a data description of a received in-phase (I) quadrature (Q) symbol. The received IQ symbol is received from a transmitter associated with impairments, and the received IQ symbol is modified from a corresponding ideal IQ symbol by the impairments. A computer processor is coupled to the data store and generates an Error-Vector Magnitude (EVM) function that describes a difference between the received IQ symbol and the ideal IQ symbol in terms of a plurality of impairment parameters indicating the impairments. The processor then determines values for the impairment parameters that quantify the impairments. The values are determined by selection of values for the impairment parameters that minimize the EVM function.

Abstract: A test and measurement system is disclosed. The system includes a data store with a data description of a received in-phase (I) quadrature (Q) symbol. The received IQ symbol is received from a transmitter associated with impairments, and the received IQ symbol is modified from a corresponding ideal IQ symbol by the impairments. A computer processor is coupled to the data store and generates an Error-Vector Magnitude (EVM) function that describes a difference between the received IQ symbol and the ideal IQ symbol in terms of a plurality of impairment parameters indicating the impairments. The processor then determines values for the impairment parameters that quantify the impairments. The values are determined by selection of values for the impairment parameters that minimize the EVM function.

Abstract: Embodiments of the invention include methods and devices for determining a phase angle offset between a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source and an optical phase adjustor, which may be embodied by a loop stretcher structured to controllably stretch a length of fiber optic cable, driven by a phase adjust driver. In other embodiments the phase angle offset information is conveyed to an oscilloscope for internal compensation.

Abstract: Embodiments of the invention include a phase adjustor for adjusting a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source for a lightwave component analyzer and an optical phase adjustor. The lightwave component analyzer drives a first test input to the DUT. An output of the DUT drives an output of the optical phase adjustor adapted to couple to an oscillator input to the DUT. A monitor selector is also included that accepts at least two outputs of the DUT and is structured to transmit a selected output of the DUT to the phase adjust driver. The phase adjust driver is structured to drive the optical phase adjustor with a control signal based on the output of the DUT that is selected by the monitor selector.

Abstract: Embodiments of the invention include a phase adjustor for adjusting a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source for a lightwave component analyzer and an optical phase adjustor, which may be embodied by a loop stretcher structured to controllably stretch a length of fiber optic cable, driven by a phase adjust driver. The lightwave component analyzer drives a first test input to the DUT. An output of the DUT drives an output of the optical phase adjustor adapted to couple to an oscillator input to the DUT. A monitor selector is also included that accepts at least two outputs of the DUT and is structured to transmit a selected output of the DUT to the phase adjust driver. The phase adjust driver is structured to drive the optical phase adjustor with a control signal based on the output of the DUT that is selected by the monitor selector.

Abstract: Embodiments of the invention include methods and devices for determining a phase angle offset between a phase angle of a local oscillator relative to a phase angle of a signal input of a Device Under Test (DUT). Some embodiments include a laser source and an optical phase adjustor, which may be embodied by a loop stretcher structured to controllably stretch a length of fiber optic cable, driven by a phase adjust driver. In other embodiments the phase angle offset information is conveyed to an oscilloscope for internal compensation.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: A crystal exhibiting a variable index of refraction in response to a voltage applied across it is driven from a lower voltage signal generator through a passive resonant circuit. The resonant frequency of the circuit is tunable by hand in order to maximize the voltage applied to the crystal from a low voltage signal generator. The impedance of the circuit is also hand adjustable in order to match that of the signal generator. The crystal and driving circuit are packaged together in a single enclosure having optically transparent windows allowing a laser beam to pass through the crystal and be modulated by it according to the frequency of the signal generator.