Abstract: A system and method for improving the transmission quality of a WDM optical communications system begins by determining the bit-error rate for an optical channel before forward error correction is performed at a receiver. The pre-corrective bit-error rate is fed back through a feed back circuit that includes a parameter adjustment module which adjusts an optical signal parameter based on the bit-error rate. As examples, the signal parameter may be a channel power, dispersion, signal wavelength, the chirp or eye shape of an optical signal. The feedback circuit may also adjust various parameters within the WDM system, including amplifier gain, attenuation, and power for one or more channels in the system. By adjusting these parameters based on a pre-corrective bit-error rate, transmission quality is improved and costs are lowered through a reduction in hardware.

Abstract: In a method of analyzing an optical communications signal, a threshold is established under control of a processor, and a decision circuit compares the amplitude of the signal to the threshold. A counter samples the output of the decision circuit and counts, over many periods of the signal, those samples indicating that the amplitude of the signal is above the threshold. The threshold generating, comparing, and counting are repeated for several thresholds within a range corresponding to an expected amplitude range of the signal. The stored counts and thresholds represent an amplitude histogram N(VT) for the signal. The derivative dN/dVT of the function N(VT) represents the probability density function (PDF) for the signal amplitude and can be used to derive performance information such as bit error rate and optical signal-to-noise ratio (OSNR).

Abstract: A received binary signal (BS) is sampled with different thresholds, the sampling results are integrated and stored. The measured probability distributions or probability density distributions can be used to draw conclusions concerning the signal quality (for example, the bit error rate) and to optimize the system.

Abstract: In a method of analyzing an optical communications signal, a threshold is established under control of a processor, and a decision circuit compares the amplitude of the signal to the threshold. A counter samples the output of the decision circuit and counts, over many periods of the signal, those samples indicating that the amplitude of the signal is above the threshold. The threshold generating, comparing, and counting are repeated for several thresholds within a range corresponding to an expected amplitude range of the signal. The stored counts and thresholds represent an amplitude histogram N(VT) for the signal. The derivative dN/dVT of the function N(VT) represents the probability density function (PDF) for the signal amplitude and can be used to derive performance information such as bit error rate and optical signal-to-noise ratio (OSNR).

Abstract: A system and method for improving the transmission quality of a WDM optical communications system begins by determining the bit-error rate for an optical channel before forward error correction is performed at a receiver. The pre-corrective bit-error rate is fed back through a feed back circuit that includes a parameter adjustment module which adjusts an optical signal parameter based on the bit-error rate. As examples, the signal parameter may be a channel power, dispersion, signal wavelength, the chirp or eye shape of an optical signal. The feedback circuit may also adjust various parameters within the WDM system, including amplifier gain, attenuation, and power for one or more channels in the system. By adjusting these parameters based on a pre-corrective bit-error rate, transmission quality is improved and costs are lowered through a reduction in hardware.

Abstract: A fiber-optic cable guide includes first and second guide walls, one or more base support elements for connecting the guide walls, and a number of securing elements which extend from the guide walls along a top portion thereof. Each securing member preferably has a length which is shorter than the spacing between the guide walls. This difference in length substantially corresponds to the diameter of a fiber-optic cable. A fastener may be included on a bottom surface of one or more of the guide walls for attaching the guide to a mounting surface, which may be a printed circuit board. Furthermore, the guide walls may be conformed to traverse any desired path along the board.

Abstract: An optical module includes a base and a plurality of cooling fins mounted to the back surface of a printed wiring board used to support a number of opto-electronic devices. To optimize heat removal; the fins are mounted on the back surface in alignment with the opto-electronic devices mounted on the front surface. The module also includes a number of fiber-optic management features which are mounted on the wiring board or materially integrated with the base and cooling fins. By combining fiber-optic management features with a heat sink, on the opposite side of board-mounted opto-electronic components, the optical module achieves increased packaging density and functionality on a per volume basis compared with its conventional counterparts.

Abstract: A fiber-optic cable guide includes first and second guide walls, one or more base support elements for connecting the guide walls, and a number of securing elements which extend from the guide walls along a top portion thereof. Each securing member preferably has a length which is shorter than the spacing between the guide walls. This difference in length substantially corresponds to the diameter of a fiber-optic cable. A fastener may be included on a bottom surface of one or more of the guide walls for attaching the guide to a mounting surface, which may be a printed circuit board. Furthermore, the guide walls may be conformed to traverse any desired path along the board.

Abstract: The oscillation frequency of a non-externally voltage-controlled oscillator produces a control signal for the monolithic integrated voltage-controlled oscillator. This control signal is opposed to the influence of the operating temperature and the manufacturing parameters of the semiconductor chip in a similar way as the frequency of the voltage-controlled oscillator. The control signal is emitted through an iterative network consisting of a monostable multivibrator, a low-pass filter, and an amplifier. The iterative network produces an actuating signal for the voltage-controlled oscillator to counteract frequency deviations.