Abstract:
An optical transmission device has a modulator, a first terminal groove, and relay groove. The modulator has a groove on a waveguide formed on a substrate. EO polymer is placed in the groove in the modulator. The modulator modulates light propagated through the waveguide by changing the phase of the light propagated through the waveguide through change of the refractive index of the EO polymer placed in the groove in the modulator by means of an electric signal. The first terminal groove is formed on the substrate and has a width larger than a width of the groove in the modulator. The relay groove is formed on the substrate and communicates with the groove in the modulator and the first terminal groove. Furthermore, the EO polymer is placed in the relay groove and the first terminal groove.
Abstract:
An optical module includes an optical device that outputs an optical signal corresponding to a control voltage, a voltage controller that applies the control voltage on which a dither signal is superimposed to the optical device, a monitor unit that monitors the optical signal output from the optical device, and outputs a monitor signal, a multiplier that multiplies the monitor signal by a reference signal corresponding to the dither signal, a filter unit that extracts a direct-current component included in a multiplication result, and a controller that causes the voltage controller to change the control voltage in accordance with the direct-current component. The controller changes the frequency of the dither signal or the reference signal such that the frequency of the reference signal is twice as large as that of the dither signal, when the direct-current component satisfies a predetermined condition.
Abstract:
An optical waveguide device includes a slot groove formed in a substrate; a pair of electrodes disposed in the slot groove; an electro-optic polymer material in the slot groove; and a step portion formed at an outer side of the slot groove, in a length direction of the slot groove.
Abstract:
An optical communication system includes an optical transmitter, and an optical receiver connected via a transmission line to the optical transmitter, in which system the optical transmitter transmits a continuous-wave light signal that enables beat detection when combined with a local oscillator signal in the optical receiver, and the optical receiver acquires a beat waveform through digital sampling by detecting the light signal using the local oscillator signal, performs frequency analysis on digitally sampled data having the beat waveform prior to demodulation, and controls the local oscillator frequency based upon the beat frequency.
Abstract:
An optical transmitter includes an optical modulator to modulate light output from a light source with a drive signal, a monitor to detect an average value and an alternating-current (AC) component of output light intensity of the optical modulator, and a controller to select one of a first bias control and a second bias control in accordance with an amplitude of the drive signal. The first bias control controls a bias voltage of the drive signal based on the average value, and the second bias control controls the bias voltage of the drive signal based on the AC component.
Abstract:
In an optical modulation device, a driver applies a drive signal based on a data signal to a modulation unit, the modulation unit modulates the light input from an LD by the drive signal, and a bias control unit calculates a bias voltage value so as to make the f0 element closer to “0,” according to a detection result in a synchronization detection unit, and supplies a bias voltage of the calculated voltage value to the modulation unit. The bias control unit stops ABC control when the data signal is in a state different from a predefined state during the ABC control, and, after the stop of the ABC control, restarts the ABC control using, as an initial value, a bias voltage value calculated before the stop of the ABC control.
Abstract:
An optical waveguide device includes a slot groove formed in a substrate; a pair of electrodes disposed in the slot groove; an electro-optic polymer material in the slot groove; and a step portion formed at an outer side of the slot groove, in a length direction of the slot groove.
Abstract:
An optical transmission device has a modulator, a first terminal groove, and relay groove. The modulator has a groove on a waveguide formed on a substrate. EO polymer is placed in the groove in the modulator. The modulator modulates light propagated through the waveguide by changing the phase of the light propagated through the waveguide through change of the refractive index of the EO polymer placed in the groove in the modulator by means of an electric signal. The first terminal groove is formed on the substrate and has a width larger than a width of the groove in the modulator. The relay groove is formed on the substrate and communicates with the groove in the modulator and the first terminal groove. Furthermore, the EO polymer is placed in the relay groove and the first terminal groove.
Abstract:
An optical module includes an optical device that outputs an optical signal corresponding to a control voltage, a voltage controller that applies the control voltage on which a dither signal is superimposed to the optical device, a monitor unit that monitors the optical signal output from the optical device, and outputs a monitor signal, a multiplier that multiplies the monitor signal by a reference signal corresponding to the dither signal, a filter unit that extracts a direct-current component included in a multiplication result, and a controller that causes the voltage controller to change the control voltage in accordance with the direct-current component. The controller changes the frequency of the dither signal or the reference signal such that the frequency of the reference signal is twice as large as that of the dither signal, when the direct-current component satisfies a predetermined condition.
Abstract:
An optical receiver receives coherent light. The optical receiver includes an amplitude adjuster, a signal processor, and a controller. The amplitude adjuster adjusts amplitude of an input signal to output an analog signal. The signal processor receives a digital signal generated from the analog signal output from the amplitude adjuster, extracts clock components from the digital signal, and after establishing synchronization between the clock components and data components, extracts the data components from the digital signal to process the data components. The controller sets amplitude of the analog signal to first amplitude before establishment of synchronization by the digital signal, and changes the set amplitude to second amplitude that is smaller than the first amplitude after the establishment of synchronization.