Effects of Timing Noise on Square-Wave Optoelectronic Oscillators

David S Citrin

doi:10.3390/app112412038

Abstract

Optoelectronic oscillators produce microwave-modulated optical beams without external modulation. The most commonly studied types produces narrow-band output, i.e., optical output modulated by a sinusoid, in which case phase noise determines key figures of merit that limit device performance. Nonetheless, other types of modulated signals have been exhibited by optoelectronic oscillators, including square waves. In this work we provide a theoretical treatment of the power spectral density of a microwave self-modulated optical periodic, but non-sinusoidal, oscillator in the presence of timing noise (as phase noise is only defined for a single sinusoid) and focus on the case of square waves. We consider the effects of timing noise on the power spectral density and autocorrelation function of the modulation signal.

Highlights

Narrow-band optoelectronic oscillators (OEO) comprise a class of optoelectronic devices that spontaneously produce a narrow-band optical signal, which is amplitudemodulated by a sinusoid of microwave frequency [1,2,3,4,5,6,7]
SW generation is achieved without external modulation, but the square waveform results from the internal dynamics of the system
We presented an analytically tractable model for a NS OEO, considering three cases: (A) a reference oscillator is absent, in which case the NS OEO is a self-sustaining oscillator; (B) an ideal reference oscillator is present, and the NS OEO is synchronized to the reference oscillator, maintaining the timing, to be close to the absolute time standard; and (C) a reference oscillator is present that has finite bandwidth, and the NS OEO is synchronized to the reference oscillator, though the timing is not locked to the absolute time

Summary

Introduction

Narrow-band optoelectronic oscillators (OEO) comprise a class of optoelectronic devices that spontaneously produce a narrow-band optical signal, which is amplitudemodulated by a sinusoid of microwave frequency [1,2,3,4,5,6,7]. By OEO, we refer, in general, to optoelectronic-based systems that spontaneously produce microwave-modulated optical signals, i.e., without external modulation. We have shown that a laser diode with time-delayed optical feedback [6] or with combined optical and optoelectronic feedback [7] can result in output of a narrow-band microwave-modulated optical signal. OEO’s spontaneously producing other types of amplitude modulation [8], such as square waves (SQ) [9] and pulses trains [10], have recently been demonstrated. SW generation is achieved without external modulation, but the square waveform results from the internal dynamics of the system

Methods

Results

Conclusion