Abstract: An optical modulator achieving high extinction ratio and an optical modulator system. By a control system performing an adjustment method comprising predetermined steps by applying a bias voltage daringly to a modulation electrode for switching the USB signal and LSB signal of an established optical SSB modulator or optical FSK modulator, a means for adjusting bias voltage applied to each bias electrode preferably automatically is provided and a bias point where the extinction ratio of an optical modulator is maximized can be obtained.

Abstract: It is an object of the present invention to provide an optical frequency comb generator to generate an optical frequency comb with flat spectral properties using a single modulator. The optical frequency comb generator comprises: a drive signal system (11) and a bias signal system (14) for driving a first drive signal (9), a second drive signals (10), and bias signals (12,13) in accordance with the following Formula (I): ?A±??=?/2??(I) (where ?A and ?? are defined, respectively, as ?A=(A1?A2)/2 and ??=(?1??2)/2, A1 and A2 indicate, respectively, optical phase shift amplitudes guided by the first drive signal and the second drive signal when input into the electrodes, and ?1 and ?2 indicate, respectively, the phases of the bias signals applied to the first waveguide and the second waveguide).

Abstract: It is an object of the present invention to provide a method and a device for automatically calibrating a light intensity measurement device. The device (1) includes an optical switch (3) for switching a route of output from an optical intensity modulator (2), an optical attenuator (5) arranged on a first waveguide (4), a second waveguide (6), a light intensity measurement device (7), a control device (8) for receiving light intensity information measured by the light intensity measurement device (7) and controlling the signal to be applied to the optical intensity modulator (2), and a signal source (9) for receiving a control signal of the control device (8) and adjusting the signal to be applied to the optical intensity modulator (2).

Abstract: The present invention is to provide an optical modulating system for generating a signal of a frequency (f0+2fm) and a signal of a frequency (f0?2fm) and suppressing a signal of a frequency (f0) by a DSB-SC modulator. A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f0) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f0) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

Abstract: A quadrature amplitude modulation (QAM) signal generator, which can obtain optical signals such as QAM signals without handling multilevel electrical signals, can be produced by using a plurality of parallel Mach-Zehnder modulators (MZMs), such as quadruplex parallel MZMs (QPMZM). The quadrature amplitude modulation (QAM) signal generator includes a first waveguide, a first quadrature phase-shift-keying (QPSK) signal generator provided on the first waveguide, a second waveguide connected with the first waveguide at a wave-combining point, and a second quadrature phase-shift-keying (QPSK) signal generator provided on the second waveguide.

Abstract: It is an object of the present invention to provide an optical switch system using optical interference. An optical switch system (1) comprises an input part (2) of an optical signal, a branching part (3) of the signal, a main Mach-Zehnder waveguide (MZC) (7), a first intensity modulator (9) provided on a first arm (4) for controlling an amplitude of an optical signal propagating through the first arm (4), a second intensity modulator (10) provided on a second arm (5) for controlling an amplitude of an optical signal propagating through the second arm (5), and a combining part (6) of the signals outputted from the first arm and the second arm, wherein one or both of the branching part (3) and the combining part (6) are X-branched.

Abstract: It is an object of the present invention to provide a DSB-SC system capable of suppressing a third order component. The DSB-SC modulation having high extinction ratio can be realized by adjusting the first order component, which is generated by applying a modulation signal (3fm), and the third order component, which is generated by applying a basic signal (fm), to have reversed phase and the same intensity level, and then by applying the first order component to the third order component, these two components cancel each other.

Abstract: It is an object of the present invention to provide an apparatus that can obtain a multiplied harmonic signal fast and with ease, and the method using the apparatus. The object is attained by the method for obtaining a multiple harmonic signal comprises, suppressing a different parity optical signal having parity different from fundamental optical signals; suppressing residual optical signals using an optical filter after suppressing the different parity optical signal; and obtaining the frequency difference component using the fundamental optical signals, and the device realizing the method.

Abstract: In order to provide a reciprocating optical modulation system capable of obtaining a broad bandwidth, a reciprocating optical modulation system (1) of the present invention is basically provided with an optical modulator (2) modulating an output light by controlling one of an intensity, a phase and a frequency of an input light; a first fiber grating (3) transmitting a light of a predetermined frequency domain among lights inputted to and outputted from the optical modulator while reflecting lights of other frequencies; a second fiber grating (4) transmitting a light of a predetermined frequency domain among lights inputted to and outputted from the optical modulator while reflecting lights of other frequencies; and a signal source (5) generating a modulating signal to be inputted to the optical modulator (2).

Abstract: There is provided an optical modulator capable of controlling the phase of a USB signal and the phase of an LSB signal of an optical FSK modulated signal. A modulation signal is applied to a main Mach-Zehnder electrode (or an electrode C) (11) of a main Mach-Zehnder waveguide (MZC) (8) to switch the USB signal and the LSB signal, and so FSK modulation can be made. In order to control the phase of the optical signal to be outputted from the main Mach-Zehnder waveguide (MZC) (8), bias voltage is applied to the main Mach-Zehnder electrode (11), and the phases of the USB signal and the LSB signal are controlled. By doing so, FSK modulation with adjusted phases can be performed.

Abstract: An optical frequency COM generator generating an optical frequency COM having flat spectrum characteristics using a single modulator. The optical frequency COM generator has a drive signal system (11) and a bias signal system (14) which drive a first drive signal (9), a second drive signal (10) and bias signals (12, 13) to satisfy the following expression (I). ?A+??=?/2 (I). (where, ?A and ?? are defined as ?A?(A1?A2)/2 and ???(?1??2)/2, respectively, A1 and A2 represent the amplitudes of the first and second drive signals when they are inputted to the electrodes of the first and second drive signals, respectively, and ?1 and ?2represent the phases of bias voltages applied to first and second waveguides, respectively.

Abstract: It is an object to provide an optical frequency control device or the like which can quickly carry out control over a wide frequency range. The object is achieved by an optical frequency control device or the like comprised of an optical SSB modulator (2), a bias voltage source (3) for applying a bias voltage to the optical SSB modulator (2), and a modulating signal source (4) for applying a modulating signal to the optical SSB modulator (2), wherein the modulating signal source (4) is provided with an arbitrary waveform generator (5) for generating an electrical signal with an arbitrary waveform, and an electrical signal multiplier (6) for multiplying a frequency of the electrical signal generated by the arbitrary waveform generator (5).

Abstract: It is an object of the present invention to provide a method and a device for automatically calibrating a light intensity measurement device. The device (1) includes an optical switch (3) for switching a route of output from an optical intensity modulator (2), an optical attenuator (5) arranged on a first waveguide (4), a second waveguide (6), a light intensity measurement device (7), a control device (8) for receiving light intensity information measured by the light intensity measurement device (7) and controlling the signal to be applied to the optical intensity modulator (2), and a signal source (9) for receiving a control signal of the control device (8) and adjusting the signal to be applied to the optical intensity modulator (2).

Abstract: It is an object of the present invention to provide an optical modulator which is capable of adjusting optical intensity of optical signals which contains non-desired components so that the intensity of the components become at a similar level, whereby the optical modulator is capable of effectively suppressing the non-desired components when the optical signals are combined.

Abstract: It is an object of the present invention to provide a DSB-SC system capable of suppressing a third order component. The DSB-SC modulation having high extinction ratio can be realized by adjusting the first order component, which is generated by applying a modulation signal (3fm), and the third order component, which is generated by applying a basic signal (fm), to have reversed phase and the same intensity level, and then by applying the first order component to the third order component, these two components cancel each other.

Abstract: It is an object of the present invention to provide an optical modulation system capable of suppressing a carrier component (f0) and a high order component (such as a second order component (f0±2fm)). The optical modulation system includes Mach-Zehnder waveguide (8), a first intensity modulator (9) provided on a first arm (4), a second intensity modulator (10) provided on a second arm (5), a first main Mach-Zehnder electrode (MZCA electrode) (13a), and a second main Mach-Zehnder electrode (MZCB electrode) (13b). Non-desired components propagating the respective arms are made to have reverse phase before optical signals are combined, whereby the optical modulation system is capable of suppressing the non-desired components when the optical signals are combined.

Abstract: The present invention is to provide an optical modulating system for generating a signal of a frequency (f0+2fm) and a signal of a frequency (f0?2fm) and suppressing a signal of a frequency (f0) by a DSB-SC modulator. A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f0) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f0) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

Abstract: In order to provide a reciprocating optical modulation system capable of obtaining a broad bandwidth, a reciprocating optical modulation system (1) of the present invention is basically provided with an optical modulator (2) modulating an output light by controlling one of an intensity, a phase and a frequency of an input light; a first fiber grating (3) transmitting a light of a predetermined frequency domain among lights inputted to and outputted from the optical modulator while reflecting lights of other frequencies; a second fiber grating (4) transmitting a light of a predetermined frequency domain among lights inputted to and outputted from the optical modulator while reflecting lights of other frequencies; and a signal source (5) generating a modulating signal to be inputted to the optical modulator (2).

Abstract: An optical modulator achieving high extinction ratio and an optical modulator system. By a control system performing an adjustment method comprising predetermined steps by applying a bias voltage daringly to a modulation electrode for switching the USB signal and LSB signal of an established optical SSB modulator or optical FSK modulator, a means for adjusting bias voltage applied to each bias electrode preferably automatically is provided and a bias point where the extinction ratio of an optical modulator is maximized can be obtained.

Abstract: A photoelectric oscillator includes a laser beam projection unit; an optical modulator on an optical path extending from the projection unit, which optical modulator outputs a modulated signal or an optical signal containing a harmonic of the modulated signal and includes a modulation electrode whose resonant frequency band includes the frequency band of the modulation signal; a photoelectric converter for converting the output of the optical modulator to an electric signal; a feedback circuit for selecting from the radio-frequency electric signal obtained from the photoelectric converter an electric signal to be re-supplied to the optical modulator; and an output section for outputting an optical signal containing the modulation signal or a harmonic of the modulation signal or outputting the modulation signal or a harmonic of the modulation signal.