Mixing and modulating methods and structures using nonlinear optical amplifiers
AssigneeHughes Electronics Corporation
InventorsJuan F. Lam, Ronald R. Stephens, Gregory L. Tangonan
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Abstract
Mixing and modulating methods are described for nonlinear optical amplifiers (30) which can generate intermodulation products of radio-frequency signals in an optical carrier signal (26) without the penalty of an optical conversion loss and without the need for radio-frequency mixers, electro-optic modulators and expensive polarization-maintaining optical fibers. The radio-frequency signals can be applied to either a bias port (36) or an optical input port (32) of the optical amplifier and are used to upconvert and downconvert signals in phased-array antenna and remote antenna embodiments of the invention.
Claims50
A method of generating intermodulation products of a plurality of electronic signals in an optical carrier signal, comprising the steps of:
- amplifying said optical carrier signal through an optical amplifier which has a bias port and a nonlinear transfer function between an optical input port and an optical output port;
- coupling a first one of said electronic signals into a selected one of said bias port and said optical input port;
- and
- coupling a second one of said electronic signals into a selected one of said bias port and said optical input port to facilitate the generation of said intermodulation products in said optical carrier signal at said optical output port by said nonlinear transfer function.
A method of frequency converting a first electronic signal with a second electronic signal, comprising the steps of:
- coupling said first electronic signal into a selected one of a bias port and an optical input port of an optical amplifier which has a nonlinear transfer function between said optical input port and an optical output port;
- coupling said second electronic signal into a selected one of said bias port and said optical input port;
- amplifying an optical signal through said optical amplifier to obtain an amplified, modulated optical signal at said optical output port which includes intermodulation products of said first and second electronic signals;
- and
- detecting said amplified, modulated optical signal to recover said intermodulation products which each represent a frequency converted version of said first electronic signal.
An antenna array for receiving a radio-frequency signal, comprising:
- an array of receptive elements which are each configured to receive a portion of said radio-frequency signal;
- a plurality of optical amplifiers, each having a nonlinear transfer function between an optical input port and an optical output port and each having a bias port coupled to a respective one of said receptive elements to receive its radio-frequency signal portion;
- and
- a plurality of photodetectors, each coupled to detect an optical signal from the optical output port of a respective one of said optical amplifiers;
- each of said optical amplifiers providing an optical input port for insertion of an optical signal which is modulated by the radio-frequency signal portion at that optical amplifier's bias port and detected by the photodetector at that optical amplifier's optical output port to recover the radio-frequency signal portion;
- and
- each of said optical amplifiers providing an optical input port and a bias port for insertion at either port of a local oscillator signal for frequency converting that optical amplifier's radio-frequency signal portion.
An antenna array for transmitting a radio-frequency signal, comprising:
- a plurality of optical amplifiers, each having a bias port and each having a nonlinear transfer function between an optical input port and an optical output port;
- a plurality of photodetectors, each coupled to detect an optical signal at the optical output port of a respective one of said optical amplifiers;
- and
- an array of radiative elements which are each coupled to receive a detected optical signal from a respective one of said photodetectors;
- each of said optical amplifiers providing an optical input port and a bias port for insertion at either port of at least one radio-frequency signal;
- and
- each of said optical amplifiers providing an optical input port for insertion of an optical signal which is modulated by said radio-frequency signal and detected by the photodetector at that optical amplifier's optical output port to recover said radio-frequency signal.
An antenna system, comprising:
- an antenna for recieving a radio-frequency signal;
- an optical amplifier having a nonlinear transfer function between an optical input port and an optical output port and having a bias port coupled to said antenna to receive said radio-frequency signal;
- an optical signal generator coupled to deliver an optical signal to said optical input port for modulation by said radio-frequency signal;
- and
- a photodetector coupled to said optical output port to recover said radio-frequency signal.
An antenna system, comprising:
- an optical amplifier having a nonlinear transfer function between an optical input port and an optical output port;
- a photodetector coupled to detect a radio-frequency signal carried by an optical signal at said optical output port;
- and
- an antenna coupled to receive and radiate said radio-frequency signal from said photodetector.
Dependencies are inferred from the claim text.