Kabushiki Kaisha Toshiba

Sadao Tanikoshi

Mitsuru Sugawara

Hiroyuki Ibe

Taro Shibagaki

Kazuhiko Ide

Takashi Yano

Yoshio Inagaki

Tomoaki Sugiyama

Masayuki Takami

Katsumi Kusama

Kyosuke Dobashi

Nobutaka Shinohara

Takehiko Atsumi

Masato Yoshida

Mototaka Kitajima

Tattee Khayim

Hiroyuki Agatsuma

Mitsuru Otani

Ko Koga

Takashi Cho

An optical modulating device including a driving circuit generating a driving voltage corresponding to an input signal, an oscillator generating a signal having a low frequency signal lower than that of the input signal, an MZ modulator receiving a DC bias voltage superposed with the low frequency signal and the driving voltage, to generate a modulated optical signal according to the input signal, a photoelectric converting unit for converting the modulated optical signal into an electric signal, a low frequency signal detecting circuit which extracts the low frequency signal component contained in the electric signal, multiplies the low frequency signal component by the low frequency signal outputted by the low frequency oscillator, and then extracts a DC component from a multiplied output signal, and a control circuit for extracting a maximized DC component from the low frequency signal detecting circuit by controlling the DC bias voltage.

Optical modulating device, optical transmitting apparatus using the same, method of controlling optical modulating device, and control program recording medium

Optical signals inputted to input ports are split in half by 1&#xd7;2 optical splitters respectively and the resulting signals are inputted to the input terminals of an optical matrix switch. The optical matrix switch switches between the routes of the individual optical signals and outputs the signal at any of the output ports. This enables the optical signal from the same input port to be outputted at two different output ports, which makes it possible to effect 'bridge' at the time of protection switching.

Optical switching apparatus and optical transmission apparatus

A serial transmission path switching system includes a matrix switch section for switching N&#xd7;M lines at a fixed rate. An optical receiving section is connected to receive an optical signal from an optical transmission path, photoelectrically convert it, and supply it to the matrix switch section. An optical transmitting section is connected to convert an output from the matrix switch section into an optical signal and send it to an optical transmission path. An input buffer is connected to the terminal of the optical transmission path connected to the optical receiving section to equalize the input signal from an input-side communication device, convert the signal into an optical signal, and send it to the optical transmission path. An output buffer is connected to the terminal of the optical transmission path connected to the optical transmitting section to convert an optical signal from the optical transmitting section into an electrical signal, equalize it, and output it to an output-side communication device.

Serial transmission path switching system

A module for optical communications includes a light receiving element which converts the light signal to an electric signal and an insulating substrate including first and second surfaces opposite to each other. An output section is provided on the first surface and extracts the electric signal as reverse and non-reverse signals. First and second connection terminals are connected to the output section and output the reverse and non-reverse signals. First and second wiring patterns are provided on the first surface. The first and second wiring patterns are electrically connected to one of the first and second wiring patterns and the other one thereof. The first and second wiring patterns have first and second ends, respectively. The first and second ends are provided in order in a direction intersecting with a line connecting the first and second connection terminals.

Module for optical communications for converting light and differential signals

The present invention provides a shield structure for shielding a microwave circuit device, which can establish a reliable electric contact between the ground wiring patterns of a circuit substrate, and can completely prevent external noise from entering into the circuit, with the use of a light and compact shield case. A circuit substrate has microwave components mounted thereon, ground patterns formed on peripheral portions of the upper surface of the substrate, and a ground pattern formed in the lower surface of the substrate along the entire periphery thereof. A shield case main body receiving the circuit substrate comprises a case main body, a top plate, and a bottom plate. The thickness of the case main body increases from a predetermined position such that it contacts the ground patterns. The bottom plate is coupled integral with the case main body with the circuit substrate interposed therebetween, in a state where the circuit substrate is received in the body. The shield case bottom plate has a surface, which is opposed to the lower surface of the circuit substrate and has a continuous groove formed therein along the periphery thereof. A shield line, which consists of an elastic conductor with a diameter greater than the depth of the groove, fills the continuous groove. The top plate is coupled integral with the upper surface of the shield case main body.

Shield structure for use in microwave circuit device

An apparatus and method for controlling gain automatically uses a light receiving element, a gain amplifier, a difference amplifier, a controller and a variable level circuit. The light receiving element generates electrical signals corresponding to received optical signals. The gain amplifier amplifies the electrial signals and the difference amplifier generates signals corresponding to the difference between defined level of amplified signal and predetermined level. In response to output signals from the difference amplifier, the controller generates signals for controlling gain of the gain amplifier and multiplication factor of the receiving element. The level circuit supplies signals to the receiving element in response to output signals from the controller.

Automatic gain multiplication factor control apparatus and method

N framing units block N-channel input digital signals, respectively, to provide blocked signals. The framing units respond to a common block synchronization signal from a multiplexing unit to provide the blocked signals in a time relation suitable for multiplexing. The multiplexing unit multiplexes the blocked signals from the framing units to provide a multiplexed signal (higher-order group signal).

Digital multiplexer

This invention provides a zero signal state detecting circuit for detecting zero signal state of the signal in an optical receiver or optical repeater. The zero signal state detecting circuit in accordance with the present invention comprises a level shifting circuit, a smoothing circuit, a first comparator, a peak detecting circuit and a second comparator. The output signal from the timing circuit to produce two output signals is shifted by the level shifting circuit. One of the two outputs of the level shifting circuit is smoothed by the smoothing circuit. The output of the smoothing circuit and the other one of the outputs of the level shifting circuit are compared by the first comparator and the output is detected by the peak detecting circuit. The output of the peak detecting circuit is compared by the second comparator against a reference voltage, and the zero signal state of the optical receiving signal is detected.

Growing community of inventors

Hachioji, Japan

Sadao Tanikoshi