Hybrid WDM-TDM optical communication and data link

Coherent light generators – Optical fiber laser

Reexamination Certificate

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C359S199200, C359S199200, C359S199200, C359S199200, C359S199200, C385S014000, C385S016000, C370S378000, C709S238000

Reexamination Certificate

active

06314115

ABSTRACT:

BACKGROUND AND PRIOR ART
Ultra high speed data links will become wide spread with the deployment of broadband switched digital networks and services, e.g., teleconferencing, video telephony, and computer services. The key hurdle in the commercial development of these networks is the availability of cost effective photonic technologies that will speed up the generation, transmission and processing of these vast amounts of data. Present state of the art optical communications and signal processing rely on a wavelength division multiplexed (WDM) or a time division multiplexed (TDM) hardware platform.
Thus, hardware based on multiwavelength optical signal sources capable of generating ultrashort and highly synchronized picosecond pulses are of great interest in novel photonic networks utilizing combined optical wavelength division multiplexed (WDM) and time division multiplexed (TDM) data formats. To date, multiwavelength generation has been demonstrated by either using spectral filtering of femtosecond optical pulses, or semiconductor laser based devices. See Morioka et al., “Multi WDM-Channel pulse generation from a Single Laser Source utilizing LD-pumped Supercontinuum in Optical Fibers”, PhotonTech. Lett., vol.6, no.3, 365~368, 1994; and Nuss et al. “Dense WDM with Femtosecond Laser Pulse ”, IEEE/LOS 1994 Annual Meeting, Boston, Mass., 1994.
In these approaches, the main idea is to generate femtosecond optical pulses at a low channel pulse rate. These approaches generally suffer from limited wavelength channels, the need of high power laser source, system complexity, and low single channel rates.
Furthermore, there have been various patents of general interest in this area that also fail to overcome the problems described above. U.S. Pat. No. 4,435,809 to Tsang et al. describes a passively mode locked laser having a saturable absorber that only has a single wavelength operation mode, with multiple longitudinal modes. U.S. Pat. No. 4,446,557 to Figueroa describes a mode-locked semiconductor laser with tunable external cavity where a user adjusts the cavity length which modifies the longitudinal mode spacing to generate a single wavelength output. U.S. Pat. No. 5,115,444 to Kirkby et al. describes a multichannel cavity laser where each wavelength is generated from a common cavity with each wavelength experiencing a different optical path length. Simultaneous generation of each wavelength is not feasible since the gain competition in the final optical amplifier stage will complicate and prevent simultaneous multiwavelength generation. U.S. Pat. No. 5,228,050 to LaCourse et al. describes an integrated multiple-wavelength laser array, each wavelength having its own cavity that is length adjustable to allow lasing at different wavelengths, and requires an array of lasers for the multiple wavelength generation. U.S. Pat. No. 5,319,655 to Thornton describes a multiwavelength laterally-injecting type lasers which requires the sources to be precisely aligned to one another. U.S. Pat. No. 5,524,012 to Wang et al. describes a tunable, multiple frequency laser diode that uses a multistripe semiconductor laser array to generate several wavelengths, and requires a grazing incidence angle on the diffraction grating. Using the grazing incidence angle prevents simultaneous wavelength generation. U.S. Pat. No. 5,524,118 to Kim et al. describes a wavelength-varying multi-wavelength optical filter laser using a single pump light source, which requires using an erbium doped fiber amplifier. U.S. Pat. No. 5,561,676 to Goldberg describes a compound-cavity high power, tunable modelocked semiconductor laser, that generates a single wavelength output that does not allow for multiple wavelength generation.
Another problem with multichannel generation from femtosecond lasers is that the multiple channels are generated by spectrally filtering the laser output after the optical pulse is generated. This is inefficient because the filtering process eliminates, or throws away, energy that was used in making the optical pulse.
In approaches relying on the spectral filtering of super-continuum generation, some wavelength channels may experience excess spectral incoherence, rendering them useless for data transmission.
SUMMARY OF THE INVENTION
The first objective of the present invention is to provide an ultra-high speed data and communication link based on an actively modelocked laser with multiple wavelength generation.
The second object of this invention is to provide an ultra-high speed photonic circuit based on multiwavelength generation from a semiconductor diode laser source.
The third object of this invention is to provide an ultra high-speed data and communication link based on generating multiwavelengths simultaneously from a single stripe semiconductor diode laser source.
The fourth objective is to provide a method for switching and routing multiple wavelengths simultaneously.
The subject invention hybrid WDM-TDM optical link includes a hybrid modelocked multiwavelength semiconductor laser that can simultaneously generate over 20 independent wavelength channels at rates greater than approximately 5 Gbits per second. Additionally, ultrafast optical demultiplexing that relies on an all optical clock recovery technique and nonlinear optical loop mirrors is used to demultiplex multiwavelength data down to rates suitable for electronic photoreceivers. The temporal duration of the optical pulses would mean that aggressive temporal interleaving can lead to optical data and transmission systems operating at rates in excess of approximately 800 Gbits per second, based solely on the semiconductor optical amplifier applications.
Further objects and advantages of this invention will be apparent from the following detailed description of a presently preferred embodiment which is illustrated schematically in the accompanying drawings.


REFERENCES:
patent: 4435809 (1984-03-01), Tsang et al.
patent: 4446557 (1984-05-01), Figueroa
patent: 5115444 (1992-05-01), Kirkby et al.
patent: 5210764 (1993-05-01), Bucher et al.
patent: 5228050 (1993-07-01), LaCourse et al.
patent: 5319655 (1994-06-01), Thornton
patent: 5524012 (1996-06-01), Wang et al.
patent: 5524118 (1996-06-01), Kim et al.
patent: 5548433 (1996-08-01), Smith
patent: 5561676 (1996-10-01), Goldberg
patent: 5831752 (1998-11-01), Cotter et al.
patent: 5996020 (1999-11-01), Reed
patent: 5999293 (1999-12-01), Manning
patent: 6081631 (2000-06-01), Brindel et al.
H. Shi, et al., Multiwavelength, 10 GHz Picosecond Pulse Generation from a Single-Stripe Semiconductor Traveling Wave Amplifier Using Active Modelocking in an External Cavity 1997, OSA TOPS on Ultrafast Electronics and Optoelectronics vol 13, p. 46-49.*
All-Optical Clock Recovery Using a Mode-Locked Laser, K. Smith and J.K. Lucek,Electronics Letters, Sep. 10, 1992, vol. 28. No.: 19, pp. 1814-1816.
Delfyett, et al., “High-Power Ultrafast Laser Diodes”, IEEE Journal of Quantum Electronics, vol.28 No. 10, Oct. 1992.
Zhu, et al. “Dual-Wavelength Picosecond Optical Pulse Generation Using an Actively Mode-Locked Multichannel Grating Cavity Laser”, IEEE Photonics Technology Letters, vol. 6 No. 3, Mar., 1994.
Morioka, et al.,“Multi-WDM-Channel, Gbit/s Pulse Generation from a Single Laser Source Utilizing LD-Pumped Supercontinuum in Optical Fibers”, IEEE Photonics Technology Letters, vol. 6, No. 3, Mar., 1994.
Chi-Luen Wong, et al. “Dual-Wavelength Actively Mode-Locked Laser-Diode Array with an External Grating-Loaded Cavity”, Optics Letters, vol.19, No. 18, Sep., 1994.
Nuss, et al., “Dense WDM with Femtosecond laser Pulses,” IEEE/LEOS 1994, 7th Annual Meeting, Boston, pp. 199-200 No Month.
Shi, et al., “4×2.5 -Gbit/s WDM-TDM Laser Source based on mode-loced semiconductor lasers,” at Phontonic Processing Technology and Applictions Conference, CREOL, SPIE vol. 3075, p. 60, Apr. 21, 1997, pp. 60-64.
Gee, et al., “Intracavity Gain and Absorption Dynamics of Hybrid Modelocked Semiconductor Lasers Using Multiple Quantum Well Saturable Absorbers”, American Institute of Physics, (Appl. Phys. Lett. 71, Nov., 1997.
Shi

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