An oscillator (101) for producing a carrier signal and having an opto-electronic noise suppression module (102) connected between an oscillator output coupler (104) and a control input (164) of the oscillator (101). The opto-electronic noise suppression module (102) includes an opto-electronic unit (110) for producing a first electrical signal (121) indicative of a delayed version of the carrier signal. An electrical interferometer (120) receives the first electrical signal (121) and a second electrical signal indicative of the carrier signal to produce two signals which are combined in a mixer (144) to produce a control signal (152) for the oscillator.

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Opto-electronic techniques for reducing phase noise in a carrier signal by carrier suppression

We present experimental results of coupled optoelectronic oscillators (COEO) constructed with a semiconductor optical amplifier based ring laser and a semiconductor colliding pulse mode-locked laser. Each COEO can simultaneously generate short optical pulses and spectrally pure RF signals. With these devices, we obtained optical pulses as short as 6.2 picoseconds and RF signals as high, in frequency, as 18 GHz with a spectral purity comparable with a HP8561B synthesizer. These experiments demonstrate that COEOs are promising compact sources for generating low jitter optical pulses and low phase noise RF/millimeter wave signals.

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Coupled opto-electronic oscillators

An electro-optical oscillator includes an electro-optical modulator having an electrical input port that accepts an electrical control signal and an optical output port. The electro-optical modulator is operable to generate at the optical output port an optical signal that oscillates at a frequency related to the electrical control signal. The oscillator also includes a photodetector that converts a portion of the optical signal from the optical output port of the electro-optical modulator to an electrical signal and provides the electrical signal to the electrical input port of the electro-optical modulator as the electrical control signal. An open loop gain of a feedback loop including the optical output port, the photodetector and the electrical input port is greater than one.

Opto-electronic oscillator having a positive feedback with an open loop gain greater than one

Opto-electronic oscillators having at least one Brillouin feedback loop based on the Brillouin selective sideband amplification to provide a sufficient gain for the oscillator to start and sustain an electro-optic oscillation. Such an oscillator can generate high frequency, high spectral purity, and tunable microwave signals in both optical and electrical domains.

Brillouin opto-electronic oscillators

Opto-electronic devices and techniques using Brillouin scattering to select a sideband in a modulated optical carrier signal for amplification. Two lasers respectively provide a carrier signal beam and a Brillouin pump beam which are fed into an Brillouin optical medium in opposite directions. The relative frequency separation between the lasers is adjusted to align the frequency of the backscattered Brillouin signal with a desired sideband in the carrier signal to effect a Brillouin gain on the sideband. This effect can be used to implement photonic RF signal mixing and conversion with gain, conversion from phase modulation to amplitude modulation, photonic RF frequency multiplication, optical and RF pulse generation and manipulation, and frequency-locking of lasers.

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Methods and devices based on brillouin selective sideband amplification

An electro-optical modulation system comprising optical modulator means for pulse-modulating an incoming light beam in response to a pulsed RF input signal and to a bias signal and for producing a pulse-modulated optical output which is characterized by a plurality of enveloped pulses, optical detector means (17) for producing an electrical signal which is representative of the output from the optical modulator means, average detecting means (19) for producing pulse envelope signals which are representative of the envelopes of the pulses, and a bias control circuit (20), using a plurality of pulse envelope signals, for producing the bias signal as a function of the pulse envelopes.

Xin Cheng

Papers

Bias control and method for electro-optic modulators