Abstract: In an optical switch with a mirror, the inclination angle of which varies depending on an application voltage, a low-frequency signal is superimposed on the application voltage, and a low-frequency component is detected in output light reflected on the mirror. Then, an application voltage is increased/decreased based on the detected low-frequency component.

Abstract: An optical repeater which includes a wavelength converter and a bit rate converter. The wavelength converter converts a wavelength of an optical signal from a first optical network to a wavelength of a second optical network. The bit rate converter converts a bit rate of the optical signal from the first optical network to a bit rate of the second optical network. The optical repeater transmits the optical signal from the first optical network to the second optical network at the converted bit rate and wavelength.

Abstract: Disclosed herein is an optical switch including a plurality of switch cells arranged in the form of an n×n matrix (n is an integer), each switch cell having first and second input ends and first and second output ends, and 2(n−1) reflection cells. The plural switch cells are selectively driven so that one of the first and second input ends of the switch cells in the first column is optically connected to one of the first and second output ends of the switch cells in the n-th column. (n−1) ones of the 2(n−1) reflection cells are arranged so as to optically connect the first output end of the switch cell in the first row, the i-th column (i is an integer satisfying 1≦i≦(n−1)) to the first input end of the switch cell in the first row, the (i+1)-th column.

Abstract: An optical cross-connect apparatus that realizes high throughput in optical cross-connection by performing large-scale switching. An input optical signal processing section converts wavelengths contained in each input WDM signal into wavelengths the number of which is equal to the number of WDM signals, compresses the pulse widths of the WDM signals by dividing the pulse widths by the number of the wavelengths contained in each input WDM signal, and performs a phase shift so that the phases of a plurality of compressed signal will not be the same. A wavelength switching section includes passive optical devices and distributes the optical signals processed by the input optical signal processing section according to wavelengths. An output optical signal processing section converts wavelengths contained in the optical signals distributed by the wavelength switching section into wavelengths recognized from the phases of the optical signals, expands the pulse widths of the optical signals, and outputs WDM signals.

Abstract: An optical cross-connect apparatus that realizes highly efficient optical cross-connection by performing large-scale switching.

Abstract: Disclosed herein is an optical switch including a plurality of switch cells arranged in the form of an n×n matrix (n is an integer), each switch cell having first and second input ends and first and second output ends, and 2(n−1) reflection cells. The plural switch cells are selectively driven so that one of the first and second input ends of the switch cells in the first column is optically connected to one of the first and second output ends of the switch cells in the n-th column. (n−1) ones of the 2(n−1) reflection cells are arranged so as to optically connect the first output end of the switch cell in the first row, the i-th column (i is an integer satisfying 1≦i≦(n−1)) to the first input end of the switch cell in the first row, the (i+1)-th column.

Abstract: Disclosed herein is an optical switch including a plurality of switch cells arranged in the form of an n×n matrix (n is an integer), each switch cell having first and second input ends and first and second output ends, and 2(n−1) reflection cells. The plural switch cells are selectively driven so that one of the first and second input ends of the switch cells in the first column is optically connected to one of the first and second output ends of the switch cells in the n-th column. (n−1) ones of the 2(n−1) reflection cells are arranged so as to optically connect the first output end of the switch cell in the first row, the i-th column (i is an integer satisfying 1≦i≦(n−1)) to the first input end of the switch cell in the first row, the (i+1)-th column.

Abstract: Disclosed herein is a method including the steps of wavelength division multiplexing a plurality of optical signals having different wavelengths to obtain resultant WDM signal light; transmitting the WDM signal light by an optical fiber transmission line; supplying reference light having a predetermined wavelength to the optical fiber transmission line; generating four-wave mixing in the optical fiber transmission line by the interaction of the WDM signal light and the reference light; detecting the power of light generated as the result of the four-wave mixing; and controlling the power of the WDM signal light to be supplied to the optical fiber transmission line according to the power detected. According to this method, the effect of four-wave mixing can be suppressed.

Abstract: In an optical switch with a mirror, the inclination angle of which varies depending on an application voltage, a low-frequency signal is superimposed on the application voltage, and a low-frequency component is detected in output light reflected on the mirror. Then, an application voltage is increased/decreased based on the detected low-frequency component.

Abstract: An optical switch having a plurality of switch cells. The optical switch has n inputs (n is a natural number) and m outputs (m is a natural number). The optical switch has a unit size defined as the distance between any two adjacent ones of the switch cells. The optical switch comprises a substrate having a switch size of K×L (K is an integer satisfying n≦K, and L is an integer satisfying m≦L), first and second mirrors parallel to each other and perpendicular to a principal surface of the substrate, and an optical unit providing a plurality of input optical paths for the n inputs and a plurality of output optical paths for the m outputs. The plurality of input optical paths are inclined relative to the first and second mirrors, and the plurality of output optical paths are inclined relative to the first and second mirrors. Each switch cell comprises a switch mirror provided movably relative to the substrate. With this configuration, the path dependence of loss is substantially eliminated.

Abstract: Disclosed herein is a method for wavelength conversion. In this method, an optical signal received is separated into a first polarization component having a first polarization plane and a second polarization component having a second polarization plane perpendicular to the first polarization plane. The first polarization component is supplied to a first optical waveguide structure over which a first surface acoustic wave propagates, in a direction identical with the propagation direction of the first surface acoustic wave. The second polarization component is supplied to a second optical waveguide structure over which a second surface acoustic wave propagates, in a direction opposite to the propagation direction of the second surface acoustic wave. First converted light output from the first optical waveguide structure and second converted light output from the second optical waveguide structure are combined together.

Abstract: The present invention relates to an optical device capable of operating at high speeds. This optical device includes an optical fiber, an optical semiconductor element, a base member, a signal terminal, and a pair of ground pins. The optical fiber is optically connected to the optical semiconductor element. The base member is formed of a conductor and has a first surface and a second surface. The optical semiconductor element is mounted on the first surface. The first surface and the second surface are substantially parallel to each other, for example. The signal terminal is electrically connected to the optical semiconductor element. The signal terminal is inserted through a hole extending from the first surface to the second surface of the base member and fixed in the hole filled with a glass paste so that a predetermined characteristic impedance is obtained between the signal terminal and the base member.

Abstract: Waveform degradation due to chromatic dispersion of an optical fiber is detected and compensated for. A waveform detector detects a change in waveform, based on the ratio between the powers of a plurality of frequency components or on peak or duty detection, and the frequency bandwidth of an equalizing amplifier or the chromatic dispersion of an optical fiber is controlled based on the result of the detection.

Abstract: A filter circuit and a filter integrated circuit capable of being used in a high frequency band includes a first resistor R.sub.1 connected between an input signal source and an emitter of a common-base transistor TR.sub.1, a first capacitor C.sub.1 connected between said input signal source and a reference voltage point, a second capacitor C.sub.2 connected between said input signal source and a collector of the common-base transistor TR.sub.1, and a second resistor R.sub.2 connected between the collector of the common-base transistor and the reference voltage point. Thus, a low-pass filter which operates in a high frequency band and suppresses the influence of characteristic parameters over the filter characteristic can be constructed.

Abstract: In optically coupling an optical fiber (8) inserted and fixed in a ferrule (10) to an optical device (12) provided in a housing (4), each part is mutually fixed by using a main ring (16) and a reinforcement ring (18), and a fixing point between the reinforcement ring (18) and the main ring (16) is positioned outside of a fixing point between the ferrule (10) and the main ring (16). With this constitution, the mechanical strength of an optical module can be improved, and the size of the optical module can be reduced.

Abstract: Systems for adjusting and evaluating the positional relationship between a light-receiving element and an optical fiber optically coupled thereto. The light-receiving element comprising a lens and a light-receiving portion with an electrode surface is a back incidence type having the lens located on the side opposite to the electrode surface of the light-receiving portion. The adjusting system scans the optical fiber with respect to the light-receiving element in order to obtain the intensity distribution of reflected feedback light from the electrode surface in the fiber scanning direction. The system then finds a region where the measured intensity increases in the intensity distribution and obtains the positional relationship between optical fiber and light-receiving element based on that region. The relationship thus obtained provides the basis for allowing the system to displace at least one of the optical fiber and light-receiving element so as to attain a necessary positional relationship therebetween.

Abstract: A filter circuit and a filter integrated circuit capable of being used in a high frequency band comprises a first resistor R.sub.1 connected between an input signal source and an emitter of a common-base transistor TR.sub.1, a first capacitor C.sub.1 connected between said input signal source and a reference voltage point, a second capacitor C.sub.2 connected between said input signal source and a collector of the common-base transistor TR.sub.1, and a second resistor R.sub.2 connected between the collector of the common-base transistor and the reference voltage point. Thus, a low-pass filter which operates in a high frequency band and suppresses the influence of characteristic parameters over the filter characteristic can be constructed.