Tunable optical local oscillator
First Claim
1. A tunable optical local oscillator for providing an optical local oscillator signal, the tunable optical local oscillator comprising, a laser for providing an optical carrier having a carrier frequency, a Mach-Zehnder modulator for providing a double sideband signal having first wavelength signal at a first frequency and a second wavelength signal at a second frequency, an asymmetric means for asymmetric filtering of the double sideband signal for increasing the intensity of the first wavelength signal over the second wavelength signal for providing power asymmetry between the first wavelength signal and the second wavelength signal, and a laser ring for providing a backward traveling wave and a forward traveling wave of the first wavelength signal for feeding back the first wavelength signal, the backscattering serving to cancel the first wave length signal for passing the second wavelength signal as the optical local oscillator signal.
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Accused Products
Abstract
A tunable optical local oscillator is used for optical heterodyne signal detection using an electrooptic Mach-Zehnder modulator to produce a rapidly tunable optical signal from a tunable RF frequency generator. A combination of the Mach-Zehnder modulator and optical fibers for providing stimulated Brillouin scattering are used to suppress unwanted signals for providing a spectrally pure optical local oscillator waveform. Suppression of unwanted optical signals, up to 50 dB, generated by the Mach-Zehnder modulator is obtained, resulting in high spectral purity of the optical local oscillator waveform with an extended tuning range of the tunable optical oscillator equal to the operating bandwidth of up to 60 GHz of the Mach-Zehnder modulators.
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Citations
16 Claims
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1. A tunable optical local oscillator for providing an optical local oscillator signal, the tunable optical local oscillator comprising,
a laser for providing an optical carrier having a carrier frequency, a Mach-Zehnder modulator for providing a double sideband signal having first wavelength signal at a first frequency and a second wavelength signal at a second frequency, an asymmetric means for asymmetric filtering of the double sideband signal for increasing the intensity of the first wavelength signal over the second wavelength signal for providing power asymmetry between the first wavelength signal and the second wavelength signal, and a laser ring for providing a backward traveling wave and a forward traveling wave of the first wavelength signal for feeding back the first wavelength signal, the backscattering serving to cancel the first wave length signal for passing the second wavelength signal as the optical local oscillator signal.
Specification