Optoelectronic Feedback Loop Research Articles

Iterative technique for high-resolution phase distortion compensation in adaptive interferometers

High-resolution adaptive phase distortion suppression is ex- perimentally demonstrated for laser interferometers using a liquid crystal television as a phase modulator and an optoelectronic feedback loop. The experiments are carried out for both amplitude division (Mach- Zehnder) and rotational shear types of interferometers. The suggested iterative control algorithm is based solely on interference pattern infor- mation. The results of numerical simulations of a high-resolution adap- tive system based on rotational shear type interferometers show the sys- tem's potential for atmospheric turbulence phase distortion suppression.

Injection-locked semiconductor lasers with delayed optoelectronic feedback

Optical injection and optoelectronic feedback are efficient techniques to externally control the spectral characteristics of a semiconductor laser. This paper presents theoretical and experimental results about the effects of a delayed optoelectronic feedback loop on the stability of an optically injected diode laser. In particular, negative feedback configurations (out-of-phase carrier reinjection) are shown to widen the injection-locking domain of the laser and reduce its unstable region. On the contrary, in positive feedback configurations (in-phase carrier reinjection), the laser diode generates a modulation with tunable multigigahertz frequency.

Adjustable phase control in stabilized interferometry

We report an optoelectronic feedback loop that permits the active stabilization of an interferometric setup for any chosen value of the phase between the interfering beams. This method is based on phase modulation and homodyne detection techniques. The phase can be stabilized with a precision of better than 1 deg for our experimental conditions.

Controlling Chaos of a Delayed Optical Bistable System

High-dimensional chaos was controlled with the occasional proportional feedback technique in a delayed optical bistable system which consists of a laser diode interferometer with a delayed opto-electronic feedback loop. Both the experiment and the numerical simulation showed that a large number of periodic orbits can be stabilized by controlling the chaotic attractor. The transient state of the trajectory under control was demonstrated.

Rapid continuous tuning of a single-polarization fiber ring laser

We have developed and studied what we believe is the first fiber laser operating in a single polarization at 1550 nm with PM fiber output and capable of wavelength tuning over a 20-nm bandwidth in less than 50 μs. The fast wavelength tuning speed in a fiber laser is achieved by incorporating an acousto-optic tunable filter into the laser. The same filter is used in an optoelectronic feedback loop to suppress the relaxation oscillations induced by wavelength transitions.

Optoelectronic loop that implements a mean field annealing algorithm for nonlinear noise filtering

We present an optoelectronic feedback loop that uses a mean field annealing algorithm for extracting features from noisy images. The configuration is analyzed and novel methods to reduce optical misalignment problems and intensity distortions are presented. Experimental results are reported and are found to be in good agreement with those obtained in computer simulations.

Accessing high-mode oscillations in a delayed optical bistable system

The stabilization is described of periodic orbits in a high-dimensional chaotic system which consists of a laser diode interferometer and a delayed opto-electronic feedback loop. A large number of isomer patterns of high mode oscillations in a period-four orbit, which essentially exist in a weak chaotic region without an external light signal, can be stabilized by modulating the interfered intensity with the external signal. The modulation frequency is chosen to be equal to a value near the imaginary part of the eigenvalue for one of the high order modes which are calculated from the linear stability analysis. The possibility of accessing a particular oscillation pattern with a seed signal is studied experimentally.

Generation of ultrashort light pulses in a semiconductor with a double feedback loop

A semiconductor injection laser with optical and optoelectronic feedback loops was investigated. Active mode locking of such a laser resulted in generation of picosecond light pulses at a repetition frequency dependent on the ratio of the signal transit times in the optical and optoelectronic feedback loops. The results indicated that it should be possible to construct a compact self-contained source of ultrashort light pulses without recourse to sophisticated electronic equipment.

A bilateral optocirculation circuit with three ports

A bilateral circulation circuit using LED-photodiode optoisolators is proposed. It is revealed theoretically and experimentally that bilateral and circular transmission is achieved by the enhancement of the current transfer ratio through optoelectronic positive feedback loops. Since the feedback loops are dispersed among three ports, it is possible to get circular signals in and out of optional ports. This circuit has stable positive gain and stable coupling efficiency because of optoelectronic feed-forwards. The bilateral frequency responses of gain extend over several hundred kilohertz.

LED linearisation for video bandwidth transmission employing a monolithically integrated PIN-PD

Nonlinear distortion and frequency response for light-emitting diodes in analogue video transmission are greatly improved by using a wideband optoelectronic feedback loop employing monolithically integrated PIN photodiodes. Large monitoring efficiency of more than 2% makes it easy to realise this wideband and high-gain feedback loop.