Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1991-12-09
1995-07-25
Pascal, Leslie
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359180, 359188, 375296, 455303, H04B 1000, H04B 1004
Patent
active
054367492
ABSTRACT:
A predistortion circuit for an optical communications system includes a main path for an RF modulating signal and a predistortion path for a predistortion signal, which signals are combined to modulate a laser diode. The distortion path includes a distortion generator which generates a distortion signal which is substantially the same as the distortion generated by the modulation of the transmission system with the RF modulating signals. In one implementation, the distortion generator comprises a square law device which preferably is a field effect type device. The square law device operational characteristic closely mimics the major component of distortion in optical communications systems, composite second order (CSO) distortion. In a second implementation, two square law devices are coupled in an anti-phase arrangement to substantially cancel odd order distortion components from the distortion signal and to enhance even order distortion components, particularly CSO. Another implementation illustrates a dual output distortion generator which allows for the selection of either an in phase or inverted phase distortion signal to be able to compensate for sublinear and superlinear laser diode curves without a separate phase inverter. Still another implementation of the predistortion circuit provides for the independent amplitude adjustment of different bands of the CATV spectrum to permit compensation for different channel loadings, channel spacings and channel amplitudes.
REFERENCES:
patent: 4032802 (1977-06-01), Pan
patent: 4045675 (1977-08-01), Kingsley
patent: 4056719 (1977-11-01), Waaben
patent: 4125777 (1978-11-01), O'Brien
patent: 4211979 (1980-07-01), Muraoka
patent: 4282604 (1981-08-01), Jefferson
patent: 4316141 (1982-02-01), Adolfsson
patent: 4330764 (1982-05-01), Miedema
patent: 4345482 (1982-08-01), Adolfsson
patent: 4378496 (1983-03-01), Brogardh
patent: 4462001 (1984-07-01), Girard
patent: 4561113 (1985-12-01), Naito
patent: 4600847 (1986-07-01), Baum
patent: 4613811 (1986-09-01), Vaerewyck
patent: 4654891 (1987-03-01), Smith
patent: 4709154 (1987-11-01), Rademaker
patent: 4868895 (1989-09-01), Hershberger
patent: 4908581 (1990-03-01), Honjo
patent: 4930141 (1990-05-01), Ohmagari
patent: 4989262 (1991-01-01), Saito
patent: 4992754 (1991-02-01), Blauvelt
patent: 5031235 (1991-07-01), Raskin
patent: 5101456 (1992-03-01), Islam
patent: 5126871 (1992-06-01), Jeffers
"Predistortion Linearization of Directly Modulated DFB Lasers and External Modulators for AM Video Transmission" Childs, et al., OFC '90.
"Feasibility of Multi-Channel VSB/AM Transmission on Fiber Optic Links", J. Koscinski, NCTA Technical Papers (1987), p. 24.
"Linearization of Broadband Optical Transmission Systems by Adaptive Predistortion", M. Bertelsmeier, et al., Frequenz (1984) pp. 206-212.
"Linearization of Multichannel Analog Optical Transmitters by Quasi-Feedforward Compensation Technique", Patterson, et al., IEEE Transactions on Communications, vol. Com 27, No. 3 (Mar. 1979) pp. 582-588.
"Phase-Shift Modulcation Technique for the Linearisation of Analogue Optical Transmitters", Strals, et al., Electronics Letters, (Mar. 3, 1977, vol. 13, No. 5) pp. 149-151.
"Analog Transmission of TV-Channels on Optical Fibers, with Non-Linearities Correction by Regulated Feedforward," Franckart, et al., ECOC 83--9th European Conference on Optical Communication, Elsevier Science Publishers B.V., North Holland (1983) pp. 347-350.
"Linearization of Light Emitting and Laser Diodes for Analog Broadband Applications by Adaptive Predistortion", Bertelsmeier, et al., Technical University, Merckstr, 25 D-6100 Darmstadt, DRF pp. 378-379.
"Nonlinearity and Its Compensation of Semiconductor Laser Diodes for Analog Intensity Modulcation Systems," Asatani, IEEE Transaction on Communications, (Feb. 1980), pp. 297-300.
"Linearisation of Optical Transmitters by a Quasifeedforward Compensation Technique," Straus, et al., Electronics Letters, (Mar. 17, 1977), vol. 13, No. 6 pp. 158-159.
"Linearization of LED Nonlinearity by Predistortions," Asatani, et al., IEEE Transactions on Electronic Devices, vol. ED-25, No. 2 (Feb. 1978) pp. 207-212.
"Status of 1550 nm Analog Fiber Optic systems and Performance Advantages," Pidgeon, et al., Technical Papers, SCTE Conference, Orlando, Fla. (Jan. 1991).
"Subcarrier Multiplexed Lightwave Sytem Design Considerations for Subscriber Loop Applications," Way, IEEE Journal of Lightwave Technology, vol. 7, No. 11 (Nov. 1989) 1809-1810.
Pidgeon, Jr. Rezin E.
Rand Heather H.
Pascal Leslie
Powers, III Frederick W.
Scientific-Atlanta, Inc.
Stewart Steven C.
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