A transmitter optical subassembly may include an optical modulator for modulating output light from the light source. The optical modulator has a characteristic that a current depending on amount of optical absorption has a positive correlation with an applied voltage thereto. The transistor at the second terminal is connected in series to the optical modulator. A drive voltage applied to the optical modulator and the transistor is divided into a first voltage applied to the optical modulator and a second voltage applied to the transistor. A drive current flowing through the optical modulator and the transistor depends on the control signal input to the first terminal. The first voltage is based on the drive current and is subject to the characteristic of the optical modulator. The second voltage fluctuates in response to the first voltage.

To autonomously apply a bias voltage to an optical modulator according to phase angle information provided from outside in a pluggable optical module. A pluggable electric connector (11) can communicate a communication data signal and a control signal with an optical communication apparatus (92). An optical signal output unit (13) includes a Mach-Zehnder type optical modulator including a phase modulation area and outputs an optical modulation signal (LS) modulated according to the communication data signal. An optical power control unit (14) can control optical power of the optical modulation signal (LS). A pluggable optical receptor (15) can output the optical modulation signal (LS) to an optical fiber (91). A control unit (12) controls a modulation operation of the optical signal output unit (13) and the bias voltage applied to the phase modulation area.

The control unit (12) determines the bias voltage applied to the phase modulation area according to phase angle information of the control signal (CON1). The optical signal output unit (13) applies the bias voltage determined by the control unit (12) to the phase modulation area.

To autonomously apply a bias voltage to an optical modulator according to phase angle information provided from outside in a pluggable optical module. A pluggable electric connector (11) can communicate a communication data signal and a control signal with an optical communication apparatus (92). An optical signal output unit (13) includes a Mach-Zehnder type optical modulator including a phase modulation area and outputs an optical modulation signal (LS) modulated according to the communication data signal. An optical power control unit (14) can control optical power of the optical modulation signal (LS). A pluggable optical receptor (15) can output the optical modulation signal (LS) to an optical fiber (91). A control unit (12) controls a modulation operation of the optical signal output unit (13) and the bias voltage applied to the phase modulation area.

The control unit (12) determines the bias voltage applied to the phase modulation area according to phase angle information of the control signal (CON1). The optical signal output unit (13) applies the bias voltage determined by the control unit (12) to the phase modulation area.

Cost-effective high-data-rate optical data transceivers are presented, comprising an electronic analog transversal filter simultaneously providing one or more of bandwidth compensation and forward impairment compensations for the transmitted optical signal.

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.

Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component E.sub.I of an optical signal in response to a first driving voltage V.sub.I, and the second inner MZM generates a quadrature component E.sub.Q of said optical signal in response to a second driving voltage V.sub.Q. Further disclosed is a calculation unit 52 configured for receiving an in-phase component y.sub.I and a quadrature component y.sub.Q of a desired base-band signal, and for calculating pre-distorted first and second driving voltages V.sub.I, V.sub.Q. The calculation of the pre-distorted first and second driving voltages V.sub.I, V.sub.Q is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages V.sub.I, V.sub.Q each as a function of both of said in-phase and quadrature components y.sub.I, y.sub.Q of said base-band signal.

Disclosed herein is a dual parallel Mach-Zehnder-modulator (DPMZM) device comprising a DPMZM 10 having first and second inner MZMs arranged parallel to each other. The first inner MZM generates an in-phase component E.sub.I of an optical signal in response to a first driving voltage V.sub.I, and the second inner MZM generates a quadrature component E.sub.Q of said optical signal in response to a second driving voltage V.sub.Q. Further disclosed is a calculation unit 52 configured for receiving an in-phase component y.sub.I and a quadrature component y.sub.Q of a desired base-band signal, and for calculating pre-distorted first and second driving voltages V.sub.I, V.sub.Q. The calculation of the pre-distorted first and second driving voltages V.sub.I, V.sub.Q is based on a model of said DPMZM 10 accounting for I-Q cross-talk, and using an algorithm that determines said first and second driving voltages V.sub.I, V.sub.Q each as a function of both of said in-phase and quadrature components y.sub.I, y.sub.Q of said base-band signal.

To autonomously apply a bias voltage to an optical modulator according to phase angle information provided from outside in a pluggable optical module. A pluggable electric connector (11) can communicate a communication data signal and a control signal with an optical communication apparatus (92). An optical signal output unit (13) includes a Mach-Zehnder type optical modulator including a phase modulation area and outputs an optical modulation signal (LS) modulated according to the communication data signal. An optical power control unit (14) can control optical power of the optical modulation signal (LS). A pluggable optical receptor (15) can output the optical modulation signal (LS) to an optical fiber (91). A control unit (12) controls a modulation operation of the optical signal output unit (13) and the bias voltage applied to the phase modulation area. The control unit (12) determines the bias voltage applied to the phase modulation area according to phase angle information of the control signal (CON1). The optical signal output unit (13) applies the bias voltage determined by the control unit (12) to the phase modulation area.

To autonomously apply a bias voltage to an optical modulator according to phase angle information provided from outside in a pluggable optical module. A pluggable electric connector (11) can communicate a communication data signal and a control signal with an optical communication apparatus (92). An optical signal output unit (13) includes a Mach-Zehnder type optical modulator including a phase modulation area and outputs an optical modulation signal (LS) modulated according to the communication data signal. An optical power control unit (14) can control optical power of the optical modulation signal (LS). A pluggable optical receptor (15) can output the optical modulation signal (LS) to an optical fiber (91). A control unit (12) controls a modulation operation of the optical signal output unit (13) and the bias voltage applied to the phase modulation area. The control unit (12) determines the bias voltage applied to the phase modulation area according to phase angle information of the control signal (CON1). The optical signal output unit (13) applies the bias voltage determined by the control unit (12) to the phase modulation area.

A process of estimating a transfer function or an inverse transfer function of the optical transmitter from first data obtained by the optical receiver when a first known signal is transmitted from the transmitter to the receiver, and a temporary transfer function or a temporary inverse transfer function of the optical receiver, is performed for multiple frequency offsets between the optical transmitter and the optical receiver. At this time, the transfer function or the inverse transfer function of the optical transmitter is estimated by comparing the first data obtained by compensating at least one or none of a temporary transfer function of the optical receiver and transmission path characteristics detected in the receiver, with a first known signal before transmission to which what is not compensated for the first data between the temporary transfer function of the optical receiver and the transmission path characteristic is added.