Abstract: An optical communication module includes: a circuit board on which a load including an optical device and a switch circuit provided between a power supply and the load are implemented; a case configured to accommodate the circuit board; and a winding configured to be electrically connected to the switch circuit and the load. The case has a protrusion. The protrusion penetrates the winding. The winding, the case and the protrusion configures an inductor.

Abstract: An electromagnetic wave suppression material is fixed to a case of a communication module. The electromagnetic wave suppression material suppresses radiation of electromagnetic waves by coming into contact with a cage that is a module insertion portion of a chassis when the communication module is inserted into the cage. A piezoelectric element is provided on the case, and located between the case and the electromagnetic wave suppression material. When the communication module is inserted into the cage, the controller applies a voltage to the piezoelectric element to stretch it by the applied voltage, thereby increasing contact pressure between the cage and the electromagnetic wave suppression material.

Abstract: An optical transmission device for controlling an optical signal output includes a return light detection section for detecting return light of the optical signal transmitted via the optical transmission line; a superimposed light transmission section for generating superimposed light having a superimposed basic low-frequency wave and transmitting the light when return light is detected by the return light detection section; a return light identification section for identifying the return light detected by the return light detection section as Fresnel light caused by a disconnection of the optical connector or Stokes light caused by stimulated Brillouin scattering based on an analysis result of the return superimposed light with respect to the superimposed light transmitted by the superimposed light transmission section.

Abstract: An electromagnetic wave suppression material is fixed to a case of a communication module. The electromagnetic wave suppression material suppresses radiation of electromagnetic waves by coming into contact with a cage that is a module insertion portion of a chassis when the communication module is inserted into the cage. A piezoelectric element is provided on the case, and located between the case and the electromagnetic wave suppression material. When the communication module is inserted into the cage, the controller applies a voltage to the piezoelectric element to stretch it by the applied voltage, thereby increasing contact pressure between the cage and the electromagnetic wave suppression material.

Abstract: After implementing a scrambler upon an electric signal of digital signals to be transmitted to a user terminal, this electric signal is converted into a digital optical signal, and an analog optical signal and this digital optical signal are multiplexed by wavelength division multiplexing, thereby reducing influence of cross-talk interference that is exerted on the analog optical signal by the digital optical signal.

Abstract: After implementing a scrambler upon an electric signal of digital signals to be transmitted to a user terminal, this electric signal is converted into a digital optical signal, and an analog optical signal and this digital optical signal are multiplexed by wavelength division multiplexing, thereby reducing influence of cross-talk interference that is exerted on the analog optical signal by the digital optical signal.

Abstract: An optical receiver comprising: a photoelectric converting unit converting an input optical signal into an converted electrical signal; a splitting unit splitting the converted electrical signal into a plurality of split electrical signals; an amplifier amplifying one of the plurality of the split electrical signals with a first input time constant and thereby outputting an output signal; a detection circuit detecting an interruption of the input optical signal with a second input time constant on the basis of one of the plurality of the split electrical signals other than the one of the plurality of the split electrical signals input to the amplifier and thereby outputting a detection signal; and a delay circuit configured to delay the detection signal; wherein, the second input time constant of the detection circuit is smaller than the first input time constant of the amplifier.

Abstract: In an optical module in which a transmitter and a receiver that respectively outputs and receives optical signals are stored in a casing, the transmitter and the receiver are connected to a common power line and to a common ground line, and a ferrite bead is arranged on the ground line in the receiver. The ferrite bead absorbs a high-frequency current component out of components in an electric signal passing through the ground line on which the ferrite bead is arranged. An inductance component that evolves on a ground line and a power line of a light receiving element and oscillation of a series resonance circuit that is formed of a capacitance component of the light receiving element are suppressed to reduce crosstalk.

Abstract: An optical device includes optical parts including a laser diode element accommodated in a housing. A bimorph-type piezoelectric element is arranged in a vicinity of the laser diode element and has a free end contacting one of the laser diode element, a support member supporting the laser diode element, and the housing. A control circuit controls an operation of the bimorph-type piezoelectric element.

Abstract: An optical transmission device for controlling an optical signal output includes a return light detection section for detecting return light of the optical signal transmitted via the optical transmission line; a superimposed light transmission section for generating superimposed light having a superimposed basic low-frequency wave and transmitting the light when return light is detected by the return light detection section; a return light identification section for identifying the return light detected by the return light detection section as Fresnel light caused by a disconnection of the optical connector or Stokes light caused by stimulated Brillouin scattering based on an analysis result of the return superimposed light with respect to the superimposed light transmitted by the superimposed light transmission section.

Abstract: An optical receiver comprising: a photoelectric converting unit converting an input optical signal into an converted electrical signal; a splitting unit splitting the converted electrical signal into a plurality of split electrical signals; an amplifier amplifying one of the plurality of the split electrical signals with a first input time constant and thereby outputting an output signal; a detection circuit detecting an interruption of the input optical signal with a second input time constant on the basis of one of the plurality of the split electrical signals other than the one of the plurality of the split electrical signals input to the amplifier and thereby outputting a detection signal; and a delay circuit configured to delay the detection signal; wherein, the second input time constant of the detection circuit is smaller than the first input time constant of the amplifier.

Abstract: An optical signal receiving apparatus, able to detect a bit rate of a received signal by a low cost and able to change to a suitable reception band width corresponding to the received bit rate, provided with a bit rate detection circuit detecting a bit rate from a consumed current flowing through a CMOS inverter (CMOS-INV) connected to an output of a PIN photodiode converting an input optical signal to an electrical signal and a control circuit controlling a reverse bias voltage applied to a variable capacity diode provided at any location in the PIN photodiode or reception apparatus.

Abstract: A line trouble detecting circuit comprises a peak detecting circuit, a first comparison circuit, a bottom detecting circuit, a bottom detecting circuit, a second comparison circuit, and a signal keeping circuit. The peak detecting circuit detects a peak voltage of amplitude of the one of the differential signal. The first comparison circuit compares an output of the peak detector and a first reference voltage. The bottom detecting circuit detects bottom voltage of the amplitude of the one of the differential signal. The second comparison circuit compares an output of the bottom detecting circuit and a second reference voltage. The signal keeping circuit keeps a signal from the first comparison circuit or the second comparison circuit.

Abstract: In an optical module in which a transmitter and a receiver that respectively outputs and receives optical signals are stored in a casing, the transmitter and the receiver are connected to a common power line and to a common ground line, and a ferrite bead is arranged on the ground line in the receiver. The ferrite bead absorbs a high-frequency current component out of components in an electric signal passing through the ground line on which the ferrite bead is arranged. An inductance component that evolves on a ground line and a power line of a light receiving element and oscillation of a series resonance circuit that is formed of a capacitance component of the light receiving element are suppressed to reduce crosstalk.

Abstract: The present invention is an optical apparatus which enables highly accurate detection of the LD ambient temperature by means of a simple constitution. The apparatus of the present invention therefore comprises a laser diode for emitting output light; a photodiode disposed in proximity to the laser diode; a forward bias supplier for supplying forward bias voltage to the photodiode when the laser diode is not emitting the output signal light; and an ambient temperature detection unit for detecting ambient temperature of the laser diode based on a terminal voltage of the photodiode to which the forward bias voltage is supplied by the forward bias supplier.

Abstract: After implementing a scrambler upon an electric signal of digital signals to be transmitted to a user terminal, this electric signal is converted into a digital optical signal, and an analog optical signal and this digital optical signal are multiplexed by wavelength division multiplexing, thereby reducing influence of cross-talk interference that is exerted on the analog optical signal by the digital optical signal.

Abstract: In a light transmission apparatus which controls an optical excitation intensity of an amplifying optical fiber or an attenuation of an optical variable attenuator based on an output light intensity, the output light intensity is sampled. When a change rate of an input light intensity exceeds a threshold value, the optical excitation intensity or the attenuation is controlled based on the output light intensity immediately before the change rate exceeds the threshold value. Accordingly, an occurrence of an optical surge is prevented and it is made possible to output an optical signal free from a signal error or a signal disconnected state.

Abstract: An optical amplifier amplifies a light signal inputted to an optical amplifier fiber and outputs an amplified light signal, by exciting the fiber with an excitation light. The optical amplifier can keep its output light level constant and stable and reduce the excitation light when the light inputted to the fiber is cut off, just by detecting the optical output level at a post-stage of the fiber. The optical amplifier comprises a first control circuit, a second control circuit and a selector circuit. The first control circuit amplifies the difference between a first predetermined voltage and an o/e-converted voltage of the optical amplifier fiber output light to output an amplified voltage. The second control circuit amplifies the difference between the o/e-converted voltage of the excitation light and a selected one of the first control circuit output voltage and a second predetermined voltage to output an amplified voltage and controls the excitation light based on the second control circuit output voltage.

Abstract: The present invention provides an optical amplifier for amplifying a light signal inputted to an optical amplifier fiber and outputting an amplified light signal, by exciting the fiber with an excitation light. The optical amplifier can keep its output light level constant and stable and reduce the excitation light when the light inputted to the fiber is cut off, just by detecting the optical output level at a post-stage of the fiber. The optical amplifier comprises a first control circuit, a second control circuit and a selector circuit. The first control circuit amplifies the difference between a first predetermined voltage and an o/e-converted voltage of the optical amplifier fiber output light to output an amplified voltage.

Abstract: An optical module includes a photodiode disposed in front of a laser diode with an offset from an optical axis of the laser diode, for monitoring the power of an optical beam emitted from the laser diode in a forward direction. The optical module further achieves switching between a transmission mode and a reception mode in response to a drive current supplied to the laser diode.