Linear optical modulator for providing chirp-free optical signal

Optical waveguides – Temporal optical modulation within an optical waveguide – Electro-optic

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

385 3, 359254, 359279, G02F 1035

Patent

active

060918640

ABSTRACT:
A dual stage optical modulator is disclosed that uses optical predistortion to achieve a high degree of linearity and also provides signals having substantially no residual phase modulation, or chirp. The modulator allows fiber optic transmission over fibers having a zero dispersion wavelength that is significantly different from the operating wavelength of the source laser without a chirp-induced dispersion penalty. In one embodiment of the modulator, an input Y-junction splits an optical input signal into a first interferometer, also referred to as a phase/intensity modulator, having first and second interferometer arms and an electrode structure for modulating the split signal. The electrode structure includes a pair of ground electrodes and a modulating electrode for receiving a first RF modulating voltage and associated DC bias. The modulating electrode is positioned between the interferometer arms but is offset from the center of the arms for providing a first asymmetric electro-optic effect through the introduction of intensity modulation and residual phase shift in the split signals. The split signals are then mixed in unequal proportions in a directional coupler and are separated into a second phase/intensity modulator that is substantially similar to the first, but which receives a second RF modulating voltage. The signals from the second phase/intensity modulator are again mixed in unequal proportions in a second directional coupler which couples the signals and provides first and second optical output signals. Linearization is achieved through optical predistortion by adjusting the DC biases and attenuating the second modulating voltage with respect to the first such that any distortion generated in the first interferometer is canceled in the second interferometer. Chirp introduced in the signals by the first interferometer is reduced in the second interferometer and directional couplers and is eliminated in at least one of the output signals by appropriately selecting the amount of asymmetric phase distortion applied to the signal in each stage.

REFERENCES:
patent: 4223977 (1980-09-01), Papuchon et al.
patent: 4390236 (1983-06-01), Alferness
patent: 4448479 (1984-05-01), Alferness
patent: 4776657 (1988-10-01), Reeder
patent: 4832431 (1989-05-01), Nolting et al.
patent: 4843350 (1989-06-01), Nazarathy et al.
patent: 4843586 (1989-06-01), Nazarathy et al.
patent: 4882775 (1989-11-01), Coleman
patent: 4932736 (1990-06-01), Su
patent: 4934775 (1990-06-01), Koai
patent: 4934776 (1990-06-01), Koai
patent: 4936645 (1990-06-01), Yoon et al.
patent: 4947170 (1990-08-01), Falk
patent: 4984861 (1991-01-01), Suchoski, Jr. et al.
patent: 4993798 (1991-02-01), Thylen
patent: 4997245 (1991-03-01), DuPuy et al.
patent: 5002353 (1991-03-01), Johnson
patent: 5010346 (1991-04-01), Hamilton et al.
patent: 5015053 (1991-05-01), Johnson
patent: 5031235 (1991-07-01), Raskin et al.
patent: 5040865 (1991-08-01), Chen et al.
patent: 5076655 (1991-12-01), Bridges
patent: 5101450 (1992-03-01), Olshansky
patent: 5109441 (1992-04-01), Glaab
patent: 5111517 (1992-05-01), Riviere
patent: 5148503 (1992-09-01), Skeie
patent: 5161206 (1992-11-01), Djupsjobacka
patent: 5168534 (1992-12-01), McBrien et al.
patent: 5184242 (1993-02-01), Henmi et al.
patent: 5249243 (1993-09-01), Skeie
patent: 5278923 (1994-01-01), Nazarathy et al.
patent: 5359449 (1994-10-01), Nishimoto et al.
patent: 5361319 (1994-11-01), Antos et al.
patent: 5373382 (1994-12-01), Pirio et al.
patent: 5408544 (1995-04-01), Seino
patent: 5473458 (1995-12-01), Mamyshev et al.
patent: 5515196 (1996-05-01), Kitajima et al.
patent: 5621560 (1997-04-01), Wood
patent: 5745613 (1998-04-01), Fukuchi et al.
patent: 5805321 (1998-09-01), Ooi et al.
Bodeep, G.E. et al., "Comparison of Second- and Third-Order Distortion in Intensity Modulated InGaAsP Lasers and a LiNbO.sub.3 External Modulator," OFC '89, paper WK-2, 1 pg.
Childs, R.B. et al., "Predistortion Linearization of Directly Modulated DFB Lasers and External Modulators for AM Video Transmission," Technical Digest, Optical Fiber Communication Conf., Optical Society of America, Washington, D.C., 1990, paper WH-6, 1 pg.
Donaldson, A. et al., "Linearity Considerations in High Performance Amplitude Modulators," IEE Colloquium on `Analogue Optical Communications,` Digest No. 156, Dec. 1989, pp. 4/1-5.
Farwell, M. et al., "An Electrooptic Intensity Modulator with Improved Linearity," IEEE Photonics Technology Letters, vol. 3, No. 9, 1991, pp. 792-794.
Kanbara, H. et al., "Optical Kerr Shutter Using Organic Nonlinear Optical Materials in Capillary Waveguides," IEEE Photonics Technology Letters, vol. 3, No. 9, Sep. 1991, pp. 795-797.
Koai, K.T. et al., "Digital and Quasi-Linear Electrooptic Modulators Synthesized from Directional Couplers," IEEE Journal of Quantum Electronics, vol. QE-22, No. 12, Dec. 1986, pp. 2191-2194.
Lam, J.F. et al., "A Novel Optical Modular System with Enhanced Linearization Properties," IEEE Transactions Photonics Technology Letters, vol. 3, No. 12, Dec. 1991, pp. 1102-1104.
Lin, Z.-Q. et al., "Reduction of Imtermodulation Distortion of Interferometric Optical Modulators Through Incoherent Mixing of Optical Waves," Electronics Letters, vol. 26, No. 23, Nov. 8, 1990, pp. 1980-1982.
Lin, Z.-Q. et al., "Waveguide Modulators with Extended Linear Dynamic Range--A Theoretical Prediction," IEEE Photonics Technology Letters, vol. 2, No. 12, Dec. 1990, pp. 884-886.
Liu, P.-L. et al., "In Search of a Linear Electrooptic Amplitude Modulator," SPIE Conference, 1990, 11 pgs.
Liu, P.-L. et al., "In Search of a Linear Electrooptic Amplitude Modulator," IEEE Photonics Technology Letters, vol. 3, No. 2, Feb. 1991, pp. 144-146.
Saleh, A.M. et al., "Compensation of Nonlinearity in Semiconductor Optical Amplifiers," Electronic Letters, vol. 24, No. 15, Jul. 21, 1998, pp. 950-952.
Skeie, H. et al., "Linearization of Electro-optic Modulators by a Cascade Coupling of Phase Modulating Electrodes," SPIE Conference, vol. 1583, Sep. 1991, pp. 153-164.
Suto, K. et al., "Intermodulation Distortion in 48 TV Channel FM-FDM Optical Transmission," IEEE Photonics Technology Letters, vol. 3, No. 9, Sep. 1991, pp. 844-846.
Wu, J. et al., "Linearization of Laser-Diode Nonlinearity of Broadband Analogue Fibre-Optic Communication," International Journal of Optoelectronics, vol. 3, No. 6, 1988, pp. 523-533. month.
Zolotov, E.M. et al., "Integrated Optical Mach-Zehnder Modulator with a Linearized Modulation Characteristic," Sov. J. Quantum Electron., vol. 18, No. 3, Mar. 1988, pp. 401-402.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Linear optical modulator for providing chirp-free optical signal does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Linear optical modulator for providing chirp-free optical signal, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Linear optical modulator for providing chirp-free optical signal will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2045832

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.