Tutorial on optoelectronic oscillators

Abstract

Microwave photonic approaches for the generation of microwave signals have attracted substantial attention in recent years, thanks to the significant advantages brought by photonics technology, such as high frequency, large bandwidth, and immunity to electromagnetic interference. An optoelectronic oscillator (OEO) is a paradigmatic microwave photonic oscillator that produces microwave signals with ultra-low phase noise, thanks to the high-quality-factor of the OEO cavity that is achieved with the help of optical energy storage elements, such as low-loss optical fiber or a high-quality-factor optical resonator. Different OEO architectures have been proposed to generate spectrally pure single-frequency microwave signals with ultra-low phase noise. Multiple oscillation mode control methods have been proposed in recent years to obtain different kinds of microwave signals. With the rapid development of photonic integration technologies, prototypes of integrated OEOs have been demonstrated with compact size and low power consumption. Moreover, OEOs have also been used for sensing, computing, and signal processing. This Tutorial aims to provide a comprehensive introduction to the developments of OEOs. We first discuss the basic principle and the key phase noise property of OEOs and then focus on its developments in spectrally pure low phase noise signal generation and mode control methods, its chip-scale integration, and its applications in various fields.

Microwave Photonic Signal Generation in an Optically Injected Discrete Mode Semiconductor Laser

“…Compared with microwave synthesis using electronics, which has been extensively explored and developed over the past decades, high-frequency microwave photonic (MWP) signal generation in the optical domain is more convenient and cost-effective. Various approaches of MWP signal generation can generally be classified into optical heterodyning [13,14], direct and external modulation [15][16][17], self-pulsating and mode-locking [18,19], optoelectronic oscillators (OEOs) [20][21][22][23][24], and laser dynamics of period-one (P1) [25][26][27][28][29][30][31][32][33][34][35][36]. The optical heterodyne technique can easily achieve terahertz photonic microwaves by beating between two optical beams with certain wavelength spacing, as such the technique has very wide tunability [13].…”

“…On the other hand, MWP signal generation utilizing external modulation can attain very high frequency and low phase noise microwave signals, but there is a drawback resulting from the insertion loss of the modulators [16]. An OEO is another paradigmatic method to obtain narrow-linewidth microwave signals in both the electrical and optical domains by introducing a feedback loop as a high-quality-factor optoelectronic oscillating cavity to a pump laser [20][21][22][23][24]. Consequently, the phase noise of generated microwaves can be comparable with that produced by mode-locked lasers [19], but the frequency tunability is compromised.…”

All-optical microwave feedback oscillator with atomic cell resonator

“…The phase noise spectrum is well-described by the power-law performances represent an important advance for CPT oscillators, since they are at least one order of magnitude better than those described in Refs 15,18,19 . However, at the present state, they are not yet at the level of state-of-the-art sapphire oscillators 34 , delay-line 24 and micro-resonator-based OEOs 35 or standard CPT clocks 5,7,8 . The main limitation of the present approach is represented by the phase fluctuations induced by the sustaining loop, in particular the EOM stage, that are directly converted into frequency noise through the CPT oscillator loop.…”

“…These approaches have been used to phase-lock, to a microwave atomic cell frequency reference, neighboring modes of multi-mode 21 or current-modulated lasers 22 , or to construct self-oscillating atomic cell oscillators [17][18][19]22 . In this paper, we investigate the unusual concept of a CPTbased vapor cell atomic feedback oscillator [17][18][19] , comparable in its architecture to those of opto-electronic oscillators (OEOs) 23,24 , with the fiber delay line being replaced by the alkali vapor cell. In our setup, a high-Q atomic resonance, initiated through CPT in a buffer-gas filled Cs vapor cell, is detected with a fast photodiode, amplified and sustained in a loop oscillator configuration, by driving back through a frequency divider, a diode laser modulated with a fibered Mach-Zehnder electro-optic modulator (EOM).…”

Externally-Triggered Spiking and Spiking Cluster Oscillation in Broadband Optoelectronic Oscillator

“…PTOELECTRONIC oscillators (OEOs) are self-consistent hybrid time-delay feedback oscillation systems composed of optical and electrical links. With the assistance of narrowband filtering, OEOs working in the quasi-linear status are recognized as a promising candidate to generate microwave signals with ultra-low phase noise [1]- [4]. In fact, the nonlinear feedback introduced by electro-optic and photoelectric conversion in a broadband OEO also leads to rich dynamic phenomena such as periodic signal, chaotic breathing and high-dimensional chaos generation [5]- [11].…”