Abstract: The present invention relates an optical waveform measuring apparatus designed to eliminate the polarization dependency of an intensity correlation signal without a polarization diversity arrangement. The apparatus comprises a sampling light outputting unit for outputting a sampling light pulse to sample light under measurement, a sampling result outputting unit for developing a nonlinear optical effect stemming from the light under measurement and the sampling light pulse from the sampling light outputting unit to output light corresponding to a result of the sampling of the light under measurement, and a polarization state control unit for, before the start of the measurement of the light under measurement, carrying out control on the basis of a power level of the light from the sampling result outputting unit so that a polarization state of the light under measurement, which is to be inputted to the sampling light output unit, is placed into a predetermined state.

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.

Abstract: A clock extracting apparatus of the present invention arranges bit intervals of a signal light train incident on a signal light processing section at periodically uneven, makes bit intervals between a predetermined signal light and signal lights adjacent to the predetermined signal light to be longer than a switching time of an electro-optical gate, selectively demultiplexes the predetermined signal light using the electro-optical gate, and extracts a dock synchronized with the signal light train from the demultiplexed signal light. Thus, it becomes possible to easily extract a clock synchronized with an ultra-high speed signal light train.

Abstract: The method according to the present invention includes the steps of splitting an optical signal into first and second optical signals, increasing the pulse widths of the first optical signal to obtain waveform shaped light, generating clock pulses according to the second optical signal, and inputting the waveform shaped light and the clock pulses into an optical AND circuit 10 to obtain a converted optical signal. According to the present invention, it is possible to suppress amplitude noise or the like generated in the optical AND circuit due to the jitter or temporal instability of the optical signal and the clock pulses.

Abstract: An optical phase modulator made of lithium niobate or the like phase-modulates the output light of a single-wavelength laser light source 20 that emits CW light, and the phase-modulated light is inputted to a dispersion medium 22. The positive chirp and negative chirp of light to which frequency chirp is applied by phase modulation draw near in the dispersion medium and an optical pulse is generated.

Abstract: An apparatus and method generating an optical pulse of picosecond class (having a high duty ratio), which accurately and stably operates at an arbitrary repetition frequency, has a high OSNR, and is not restricted by an RF modulation frequency, are provided. New modulation spectrum components are generated by performing phase modulation for light output from a single wavelength laser light source with an optical phase modulator. The phases of the modulation spectrum components are aligned by a phase adjuster, so that a pulse wave in a time domain is generated.

Abstract: A pulse sequence is configured by making a pulse waveform output from a pulse light source into a super Gaussian pulse of the third order or higher, and input to a spectrum expanding device. The spectrum expanding device broadens the spectrum of the pulse sequence with a nonlinear medium. A modulator array extracts longitudinal mode components from the expanded spectrum, and modulates the extracted longitudinal mode components with modulation data. Lastly, the modulated longitudinal mode components are coupled and transmitted to a transmission line.

Abstract: A method of providing a multi-wavelength light source includes the steps of modulating an optical pulse source so as to output optical pulses with a designated repetition frequency, time-division multiplexing the optical pulses output by the optical pulse source so as to output optical pulses with a repetition frequency which is an integral multiple of the designated repetition frequency, and demultiplexing wavelengths of the optical pulses with the repetition frequency which is the integral multiple of the designated repetition frequency so as to output the wavelengths as the multi-wavelength light source.

Abstract: A nonlinear optical loop mirror having a first optical coupler including first and second optical paths directionally coupled together, a loop optical path formed of a nonlinear optical medium for connecting the first and second optical paths, and a second optical coupler including a third optical path directionally coupled to the loop optical path. An optical signal whose waveform is to be measured is supplied into the nonlinear optical loop mirror from the first optical path. An optical trigger having a predetermined pulse width is supplied into the nonlinear optical loop mirror from the third optical path. Information on the waveform of the optical signal is obtained according to light output from the second optical path. The predetermined pulse width of the optical trigger is set according to the required measurement accuracy, so that the waveform of the optical signal can be faithfully observed with a high time resolution.

Abstract: In the method according to the present invention, an optical signal is input into a first optical gate to suppress a space-level noise of the optical signal. Subsequently, an optical signal output from the first optical gate is input into a second optical gate to suppress a mark-level noise of the optical signal output from the first optical gate. With this configuration, the waveform of the optical signal can be shaped without O/E conversion. For example, waveform shaping independent of the modulation rate and format of the optical signal can be performed.

Abstract: An object of the present invention is to provide a separating apparatus having a simple configuration, capable of time division separating time division multiplexed signal light directly and stably.

Abstract: The method according to the present invention includes the steps of splitting an optical signal into first and second optical signals, increasing the pulse widths of the first optical signal to obtain waveform shaped light, generating clock pulses according to the second optical signal, and inputting the waveform shaped light and the clock pulses into an optical AND circuit 10 to obtain a converted optical signal. According to the present invention, it is possible to suppress amplitude noise or the like generated in the optical AND circuit due to the jitter or temporal instability of the optical signal and the clock pulses.

Abstract: In the method according to the present invention, an optical signal is input into a first optical gate to suppress a space-level noise of the optical signal. Subsequently, an optical signal output from the first optical gate is input into a second optical gate to suppress a mark-level noise of the optical signal output from the first optical gate. With this configuration, the waveform of the optical signal can be shaped without O/E conversion. For example, waveform shaping independent of the modulation rate and format of the optical signal can be performed.

Abstract: According to the present invention, a nonlinear optical loop mirror is provided, which includes a first optical coupler including first and second optical paths directionally coupled to each other, a loop optical path formed of a nonlinear optical medium for connecting the first and second optical paths, and a second optical coupler including a third optical path directionally coupled to the loop optical path. An optical signal whose waveform is to be measured is supplied into the nonlinear optical loop mirror from the first optical path. An optical trigger having a predetermined pulse width is supplied into the nonlinear optical loop mirror from the third optical path. Information on the waveform of the optical signal is obtained according to light output from the second optical path. The predetermined pulse width is set according to a required measurement accuracy.

Abstract: SC light is generated from the input signal 2, of an OTDM signal light 1 with wavelength &lgr;s1 and an input signal 2 with wavelength &lgr;s2 using an optical fiber and the like, and the wavelength of the SC light is converted into wavelength &lgr;s1 using a BPF with center wavelength &lgr;s1 (a specific-timing optical pulse with wavelength &lgr;s1 is extracted from the SC light). After the addition timing of the wavelength-converted light is adjusted by a delayer (&tgr;) both this wavelength-converted light and signal light 1 are inputted to an optical add circuit and are added.

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.