Abstract: Provided is a method of producing a skin-covered product in which a skin is bonded to a base material, the method capable of performing a roll treatment by a robot to improve work efficiency and quality, and reducing the number of production steps for producing the skin-covered product by immediately performing a rolling step after trimming the bonded skin by vacuum molding.

Abstract: An optical amplifier amplifies a wavelength-division-multiplexed optical input signal composed of optical signals having different wavelengths such that the output level of each of the optical signal is always optimized and such that the difference between the gains of the amplifier on the optical signals is minimized when the number of optical signals is two. The output level of the amplifier is controlled according to the number of the optical signals, to optimize the output level of each of the optical signals.

Abstract: The object of the present invention is to provide an optical amplifying apparatus for collectively amplifying wavelength-division multiplexed signal lights, which can perform amplification in response to input signal light, whose power level is within a wide input dynamic range, without saturating, and which suppresses the influence of the wavelength dependency of gain thereof. Thus, this optical amplifying apparatus is composed of: three optical amplifying portions connected in cascade; an optical attenuating portion for controlling the level of signal light output from the optical amplifying portion provided in the post-stage by regulating the power level of signal light input to the optical amplifying portion provided in the middle stage; and a dispersion compensation fiber provided between the middle stage and post stage optical amplifying. A gain of each of the optical amplifying portions is controlled to be constant by an AGC circuit.

Abstract: The invention provides a multi-wavelength optical batch amplification apparatus wherein, upon batch amplification of a multi-wavelength input optical signal, the powers of optical signals on the input and output sides of an optical amplifier are monitored totally or individually to control the powers of optical signals of the output optical signal of the optical amplifier so that they may be fixed equally.

Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.

Abstract: A control apparatus for an optical amplifier such as an erbium-doped optical-fiber (EDF) amplifier suppresses overshooting of ALC control at power on and at the time of input light restoration from an off condition, while ensuring quick starting. At power on and at the time of input light restoration from an off condition, an idling current (IDC) reference value generating circuit generates an IDC reference voltage that increases to a value sufficiently greater than a value in a normal operating condition with a time constant corresponding to a rise time of the EDF, and thereby controls a laser diode for pumping the EDF. The voltage may be set to a value larger than the value in the normal operating condition for a predetermined period of time by using a timer.

Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.

Abstract: An optical amplifier amplifies a wavelength division-multiplexed optical input signal composed of optical signals having different wavelengths such that the output level of each of the optical signal is always optimized and such that the difference between the gains of the amplifier on the optical signals is minimized when the number of optical signals is two. The output level of the amplifier is controlled according to the number of the optical signals, to optimize the output level of each of the optical signals.

Abstract: The optical amplifier includes a doped fiber doped with a rare earth element, a pumping light source, means for introducing signal light and pumping light into the doped fiber, detection means for detecting whether or not amplified signal light is included in light outputted from the doped fiber, and means for decreasing the intensity of the pumping light when it is detected that amplified signal light is not included. It can be possible to eliminate an influence of an optical surge arising from a characteristic of the doped fiber.

Abstract: Spontaneous emission occurring in association with direct optical amplification using an erbium-doped optical fiber is modulated with an auxiliary signal, such as a supervisory signal, for transmission of the auxiliary signal. In a first aspect of the invention, the output of an optical amplifier is passed through a variable optical band-pass filter whose transmission characteristic is varied in accordance with the auxiliary signal, to modulate the spontaneous emission component contained in the optical amplifier output. In a second aspect of the invention, the output of the optical amplifier is separated by an optical branching device into a main optical signal and part of the spontaneous emission.

Abstract: A drive circuit drives an electronic device that converts electric power into light or heat energy. The drive circuit has a switch connected to the electronic device in series, and a control circuit for providing, in response to an input control signal, a pulse modulation signal for controlling the switch. The frequency of the pulse modulation signal is higher than the response frequency of the electronic device. Alternatively, the drive circuit may have first to fourth switches disposed on both sides of the electronic device, for passing a current in different directions through the electronic device, and a control circuit for controlling the switches to change the direction and magnitude of the average of the current flowing through the electronic device in response to an input control signal.