Abstract

The autonomous optoelectronic generator (OEO) is considered in the chapter as a source of low-noise oscillations. Differential equations are considered and methods with OEO modulation with direct and external modulation are analyzed. The complexity of both approaches is related to the non-standard way of description of the nonlinear method modulation for the internal (direct) structure and the utilization of the specific Mach-Zehnder modulator for the first stage on external modulation. The purpose of the presentation is to consider the main features of OEO as a low-noise generator. This includes consideration based on the study of differential equations, the study of transients in OEO, and the calculation of phase noise. It is shown that different types of fibers with low losses at small bending radii can be used as a FOLD in OEO. The important role of the choice of a coherent laser for OEO with a small spectral line width is shown. The prospects of using structured fibers with low losses at bends of less than 10 mm in OEO are described. The results of modeling dynamic processes in OEO with direct modulation are presented.

Highlights

  • The opto-electronic oscillator structureDevelopment and creation of the compact ultra-low-noise microwave signal sources, which would be impact-resistant, is an important problem of modern radio-physics and radio engineering

  • It is shown that different types of fibers with low losses at small bending radii can be used as a FOLD in opto-electroniс oscillator (OEO)

  • We will assume that the laser in OEO has high coherence and the spectral line width is much smaller than the average generation frequency, and the laser oscillations can be considered close to sinusoidal, and with a phase component of noise with normalized amplitude noises mLmðtÞ and the phase noise component φLmðtÞ: ELðtÞ 1⁄4 1⁄2E0L þ mLmðtފ cos 1⁄22πν0Lt þ φ0L þ φLmðtފ: (1)

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Summary

Introduction

Development and creation of the compact ultra-low-noise microwave signal sources, which would be impact-resistant, is an important problem of modern radio-physics and radio engineering. Development and implementation of new compact microwave and millimeterwave oscillators with improved performance would lead to revolutionary jump in radio electronics, perhaps, comparable to discovery of the quantum-dimensional lasers or (as in radio engineering) at arriving of the high-stability quartz crystal resonator. Opto-electronic oscillators will undoubtedly find wide application in the fiberoptical communication lines as well as in on-board radar systems on millimeter- and centimeter ranges, in communication systems as low-noise local oscillators in receivers and as a master clock in transmitters, in an optical lidar technology, as sensors of different physical quantities and in many other systems [8–16]. GenerationΔvL is much smaller than the radio frequency f 0 of the OEO generation: ΔνL < < f 0 In this case, the spectrum of the modulated radiation can be represented by several harmonics. Discriminator method in OEO with the MZ modulator and in the circuit with direct amplitude modulation at suppression of the one harmonic

OEO with direct modulation and OEO with the Mach Zehnder modulator
OEO construction and its operation principle
Problem statement
Laser in OEO
Compact fiber optic delay line in OEO
OEO differential equations
Dynamics of transients in OEO DM
OEO DM system of the laser emission
10. Laser phase noise and OEO phase noise
11. OEO as the EMF correlator
12. OEO phase noise
13. Experimental investigations
Findings
14. Conclusion
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