Fujitsu Corporation

Fujitsu Optical Components Limited

Katsuhiko Hakomori

Masakazu Horishita

Hiroyuki Furukawa

Hiroshi Nishimoto

Akihiko Ichikawa

Kazuhito Ogawa

Tatsuya Nishimura

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.

Communication module

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.

Optical transmission device and optical transmission method

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.

Optical transmission system and optical transmission method

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.

Optical receiver

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.

Optical module

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. The selector circuit detects a change in the first control circuit output voltage and depending on the change, selects the first control circuit output voltage or a second predetermined voltage.

Optical amplifier

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.

Growing community of inventors

Kawasaki, Japan

Katsuhiko Hakomori