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Cross-talk free, low-noise optical amplifier
| Details |
Inventors: Dijaili, Sol P.; Patterson, Frank G.; Deri, Robert J.;
Assignee: The Regents of the University of California (Oakland, CA)
Primary Examiner: Hellner; Mark
Assistant Examiner:
Attorney, Agent or Firm: Sartorio; Henry P., Wooldridge; John P.
A low-noise optical amplifier solves crosstalk problems in optical amplifiers by using an optical cavity oriented off-axis (e.g. perpendicular) to the direction of a signal amplified by the gain medium of the optical amplifier. Several devices are used to suppress parasitic lasing of these types of structures. The parasitic lasing causes the gain of these structures to be practically unusable. The lasing cavity is operated above threshold and the gain of the laser is clamped to overcome the losses of the cavity. Any increase in pumping causes the lasing power to increase. The clamping action of the gain greatly reduces crosstalk due to gain saturation for the amplified signal beam. It also reduces other nonlinearities associated with the gain medium such as four-wave mixing induced crosstalk. This clamping action can occur for a bandwidth defined by the speed of the laser cavity. The lasing field also reduces the response time of the gain medium. By having the lasing field off-axis, no special coatings are needed. Other advantages are that the lasing field is easily separated from the amplified signal and the carrier grating fluctuations induced by four-wave mixing are decreased. Two related methods reduce the amplified spontaneous emission power without sacrificing the gain of the optical amplifier. |
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DETAILED DESCRIPTION It is an object of the present invention to use a segmented transverse lasing field to reduce crosstalk in optical amplifiers in wavelength divison multiplexed systems.
it is another object of the invention to reduce time domain crosstalk and intersymbol interference using the same structure as for the wavelength domain crosstalk reduction.
It is another object of the invention to reduce the ASE in the optical amplifier using microcavities without a commensurate decrease in signal gain.
Another object of the invention is to reduce noise in a series of semiconductor optical amplifiers by using distributed spatial filter arrangement of amplifier sections.
Still another object of the invention is to provide high-speed amplitude modulation with a good extinction ratio.
A further object of this invention is to improve the performance (in terms of output signal-to-noise ratio and effective output saturation power) of semiconductor optical amplifiers, Erbium doped fiber amplifiers, rare-earth doped waveguide optical amplifiers, and amplifiers using other gain materials such as Ti-Sapphire, NdYag, porous silicon, or any other material possessing gain by stimulated emission.
Another object of this invention is to enable a number of applications, for example: the application of this technology in the use of multichannel wavelength sources and receivers that use optical amplifiers within and outside their cavities; the use of this type of amplifier in a switch matrix; in modelocked lasers; in low noise high sensitivity applications including free-space applications; and the use of this technology in low noise laser sources.
Another object of the invention is to reduce the sensivity of the optical amplifier performance to factors such as temperature, aging, stress, power supply fluctuations, etc.
This invention solves crosstalk problems in optical amplifiers by using a segmented optical cavity oriented off-axis (e.
g.
perpendicular) to the direction of a signal amplified by the gain medium of the optical amplifier
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MEMS 
