摘要:
A method and apparatus for pulse frequency modulation for analog optical communication. A train of optical pulses is generated. The spectrum of the optical pulses in the train of optical pulses can be broadened to provide a train of broad spectrum optical pulses. The broadening can be provided by self-phase modulation. Alternatively, broad spectrum optical pulses can be provided by merely having the optical pulses be less than 1 ps duration. A desired optical frequency slice from the train of spectrum broadened optical pulses is selected by a tunable Fabry-Perot filter. A desired optical frequency slice from the broad spectrum optical pulses is selected by a tunable Fabry-Perot filter. The tunable Fabry-Perot filter has a pair of Distributed Bragg Reflectors separated by an electro-refractive section. The electro-refractive section has tuning electrodes for applying transverse electric fields to the electro-refractive section, corresponding to an analog waveform being applied to the tuning electrodes, to provide a pulse-frequency modulated train of optical pulses.
摘要:
A method and system for generating single and multi-channel optical analog pulse-position modulation waveforms are disclosed. The system comprises a frequency modulator, a continuous wave optical source, and an optical modulator. The frequency modulator receives the analog signal and converts the analog signal into a frequency modulated signal. The optical modulator modulates the continuous wave optical source with the frequency modulated signal, to produce the optical pulse-position modulated signal. The method comprises converting an analog input signal into a frequency modulated signal amplifying the frequency modulated signal and producing a large signal therein, modulating a continuous wave optical source with the large signal, therein producing the optical pulse-position modulation signal, and compressing the optical pulse-position modulation signal, therein increasing a processing gain.
摘要:
The present invention describes a microresonator that can be used as a 1:f variable coupler in a unit cell. It is described how a cascade of unit cells can be used to form a tunable, higher-order RF-filter with reconfigurable passbands. The disclosed filter structure can be utilized for the narrowband channelization of RF signals that have been modulated onto optical carriers. It is also disclosed how to utilize add/drop capabilities of the contemplated microdisks to confer connectivity and cascading in two dimensions. The present invention can conveniently provide a wavelength division multiplexing router, where an array of unit cells as provided herein can form a programmable optical switching matrix, through electronic programming of filter parameters.
摘要:
A method and apparatus for optical frequency modulation discrimination. An optical beam is split into a first optical beam and a second optical beam A first photodetector is provided, the first photodetector providing a first current responsive to the first optical beam input thereon, the first photodetector having a first photodetector spectral response and being biased such that the first current is in a first direction. A second photodetector is also provided, the second photodetector providing a second current responsive to the second optical beam input thereon, the second photodetector having a second photodetector spectral response and being biased such that the second current is in the first direction. An input of a transimpedance amplifier is coupled to an output of the first photodetector and to an input of the second photodetector to provide an output of the transimpedance amplifier proportional to the difference between the first current and the second current. A first optical filter is provided to receive the first optical beam prior to incidence upon the first photodetector and a second optical filter to receive the second optical beam prior to incidence upon the second photodetector, wherein the first photodetector spectral response and the second photodetector spectral response are each broader than respective passbands of the first optical filter and the second optical filter to provide photocurrent vs. optical frequency characteristics determined by the respective first optical filter and the second optical filter.
摘要:
A method and apparatus for converting a frequency modulated lightwave into an electrical signal that is proportional to instantaneous frequency deviations of the frequency modulated lightwave. The frequency modulated lightwave is amplified by an amount equal to or greater than a desired FM processing gain to provide an amplified frequency modulated lightwave. The amplified lightwave is filtered to restrict amplifier noise added to the frequency modulated lightwave to provide a filtered lightwave. The amplitude of the filtered lightwave is limited to remove unwanted amplitude fluctuations to provide a limited lightwave. The limited lightwave is split into a first split lightwave and a second split lightwave. The second split lightwave is delayed relative to the first split lightwave, to provide a delayed second split lightwave. The delayed second split lightwave is combined with the first split lightwave to provide:(1) a sum of first split lightwave fields and delayed second split lightwave fields, and (2) a difference of the first split lightwave fields and the delayed second split lightwave fields, the splitting, delaying and combining providing the sum and the difference having fields with parallel polarizations. The sum is detected by a first photodetector and the difference is detected by a second photodetector, the first photodetector and second photodetector being connected in series with a common terminal therebetween, the common terminal providing to a following amplifier a difference current that is proportional to a difference between first photodetector curent and second photodetector current, the difference current being proportional to instantaneous frequency deviation of the frequency modulated lightwave.
摘要:
Hand-held scraper includes a body or holder portion to which is removably secured a scraping or cutting blade. The blade is retained in place by camming the mounting tabs at its respective ends into tight frictional locking engagement with a pair of longitudinally spaced apart retaining ribs protruding downwardly in opposite outwardly disposed directions from the underneath side of the holder portion. At least one of the retaining ribs is somewhat flexible to facilitate camming of the blade into and out of assembled engagement with the holder portion with little or no flexing of the mounting tabs and no bending or yielding of the blade body whatsoever. To facilitate removal and replacement of the blade, a movable lever is provided on the underneath side of the holder portion inwardly of one of the mounting tabs. When the lever is manually pushed downwardly, the lever presses against such mounting tab, causing it to cam away from the associated mounting rib thus freeing the blade from the holder.
摘要:
There is provided in one of the embodiments of the disclosure a lithium niobate modulator structure for mitigating DC bias drift comprising a highly doped semiconductor layer patterned above an optical waveguide having one or more DC sections and an RF section, wherein a metal layer or contact is in contact with a portion of the semiconductor layer and a buffer layer is deposited in the RF section. There is provided in another embodiment of the disclosure a method for making a lithium niobate electro-optical modulator for mitigation of DC bias drift.
摘要:
The present invention relates to a laser transmitter capable of being configured to transmit one of a plurality of wavelengths. Specifically, the laser transmitter may be reconfigured using the resonance passbands of a tunable microresonator coupled with a fixed grating.
摘要:
Transversal equalization is used to obtain broadband linearization of photonic modulation. A photonic link comprises a signal path and a feed-forward path. The feed-forward path includes an optical linearizer and a transversal equalizer connected with the optical linearizer. In this way, amplitude and phase matching of the error in the signal path is obtained over a wide bandwidth. This, in turn, enables a broadband enhancement of the link's spur free dynamic range (SFDR).
摘要:
There is provided in one of the embodiments of the disclosure a lithium niobate modulator structure for mitigating DC bias drift comprising a highly doped semiconductor layer patterned above an optical waveguide having one or more DC sections and an RF section, wherein a metal layer or contact is in contact with a portion of the semiconductor layer and a buffer layer is deposited in the RF section. There is provided in another embodiment of the disclosure a method for making a lithium niobate electro-optical modulator for mitigation of DC bias drift.