摘要:
An optical communication system is disclosed including an all-optical device whose output modulated optical beam is locked to an input modulated optical beam. In a specific embodiment of the system, the device may be a self-electro-optic effect device (SEED), which is operated as an oscillator by means of an associated tank circuit. Such an embodiment permits recovery of a clock frequency from a bit stream which is input into the device. When the output of the device is directed into an optical decision element, an all-optical regenerator may be realized.
摘要:
For a group of optical amplifiers, pump beams from an array of lasers are mixed together to form a plurality of composite pump beams. Each composite pump beam is distributed to the pump port of a particular optical amplifier. The composite pump beam improves the reliability of each optical amplifier. Rather than having catastrophic failure of an optical amplifier occasioned by the failure of its pump laser, it is now possible to maintain full operation of the group of optical amplifiers even though one or more lasers fail.
摘要:
An optical communication system is disclosed including an all-optical device whose output modulated optical beam is locked to an input modulated optical beam. In a specific embodiment of the system, the device may be a self-electro-optic effect device (SEED), which is operated as an oscillator by means of an associated tank circuit. Such an embodiment permits recovery of a clock frequency from a bit stream which is input into the device. When the output of the device is directed into an optical decision element, an all-optical regenerator may be realized.
摘要:
An optical switch uses a MEMS device to insert a highly reflective shutter in a gap between a pair of coaxially aligned fibers. When the switch is closed, an input optical signal passes with little loss through the gap. When the switch is open and the shutter is positioned in the gap, an input optical signal incident on the shutter is reflected back into the input fiber. Such light is diverted by an optical circulator into a new path.
摘要:
In a transmission system having concatenated optical amplifiers, gain saturation of the optical amplifiers at any stage is caused by the extraction of power from the amplifier by the ASE and amplification of the signal and of the ASE from previous stages. Three methods of operating transmission systems are classsified as free-running, constant-total power and constant-signal power. Differences in performance of the three systems arise from the propagation of signal power and the buildup of the ASE. It is now disclosed that the buildup of ASE noise in a system of either lumped or distributed concatenated optical amplifers can be limited by operating at least a plurality of the optical amplifers to provide unsaturated gain which is greater than the loss of the system and/or each optical amplifier is operated in its saturated state.
摘要:
In a fiber optic laser controller for use in digital transmission a digital data stream and a DC bias are applied to the laser. During a monitoring period, the DC bias is stepped from a zero to a peak current. At a first threshold current, lasing occurs in response to digital `1` modulating current but not in response to digital `0` modulating current. At a second higher threshold current lasing occurs in response to both digital `1` and `0`. The threshold currents are identifiable as peaks in the second derivative d.sup.2 L/dI.sup.2 where L is the light output for an applied bias current I. A feedback circuit including a photodiode, D/A and A/D converters and a microprocessor controller are used to maintain the bias current at the second threshold current in spite of changes in the laser characteristics caused by device aging or temperature change.
摘要:
A micromirror array is used to form optical apparatus useful in WDM optical networks. In one embodiment, the micromirror array is used to insert a desired attenuation in individual channels for purposes such as equalization. In another embodiment, the micromirror array is used to form an optical monitor useful as an optical spectrum analyzer.
摘要:
A passive optical network for the downstream dense wavelength division multiplexing communication of data between a host terminal complex (HTC) and a plurality of optical network units (ONUs), and for the upstream communication of data from the ONUs to the HTC. The network includes a routing device for distributing downstream data signals contained in a common frequency band among a plurality of fiber drop lines for providing a corresponding wavelength to a corresponding ONU. The routing device also combines upstream data signals contained in a frequency band other than the downstream common frequency band, which are input to the routing device on the plurality of fiber drop lines, to a multi-wavelength signal which is provided to the HTC. In a preferred embodiment, the upstream data signals are output by the routing device to a broadcast port.
摘要:
Indiscriminately exciting the modes of a multi-mode optical fiber amplifier is avoided by an optical fiber amplifier design in which the excitation of pump modes in the core of a multi-mode fiber is controlled by controlling the pump light launching. The pump light is directed substantially along the center axis of a multi-mode fiber within a predetermined launch angle. Rather than exciting all modes, only lower order modes are affected.
摘要:
An optical attenuator for use in optical power regulation uses a shutter to control the insertion loss of a gap in a pair of substantially coaxially aligned waveguides, for example a pair of optical fibers. The shutter is part of a MEMS accuator device and is coupled to the movable one of a pair of spaced plates, the movable plate being movable by a voltage applied between the pair of plates. To regulate the power, a small portion of the optical power is abstracted and used to derive a control voltage that is applied to the optical attenuator for varying the attenuation inserted in the optical wave path.