Coupled opto-electronic oscillators can generate microwave signals with very low phase noise. Several approaches for modelling these oscillators exist, but none of them include the fast carrier ...dynamics of the mode-locked laser, due to computational limitations. In this work, we present a new model, that is based on a computationally efficient model for semiconductor mode-locked lasers, which is capable of simulating both the fast laser dynamics and the long term phase stability. We use it to model the phase noise of a hybridly integrated coupled opto-electronic oscillator. The results show that a timing jitter of down to <inline-formula><tex-math notation="LaTeX">\mathbf {\sim} \text{0.2}</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">\text{ps}</tex-math></inline-formula> in the integration range from <inline-formula><tex-math notation="LaTeX">\text{10}</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">\text{kHz}</tex-math></inline-formula> to <inline-formula><tex-math notation="LaTeX">\text{10}</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">\text{MHz}</tex-math></inline-formula> is achievable when using an integrated delay line of <inline-formula><tex-math notation="LaTeX">\text{10.2}</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">\text{m}</tex-math></inline-formula> in the opto-electronic feedback path. It is also shown that by increasing both gain and bandwidth of the opto-electronic feedback link, the timing jitter is reduced. Together, these results present a path towards low phase noise performance of hybridly integrated coupled opto-electronic oscillators, and the model serves as a new design tool. Such oscillators might increase, for example, the spectral efficiency in future data communication systems and thus enable higher data rates.
Optical fibers containing multiple cores are being developed towards capacity enhancement in space-division multiplexed optical communication networks. In many cases, the fibers are designed for ...negligible direct coupling of optical power among the cores. The cores remain, however, embedded in a single, mechanically-unified cladding. Elastic (or acoustic) modes supported by the fiber cladding geometry are in overlap with multiple cores. Acoustic waves may be stimulated by light in any core through electrostriction. Once excited, the acoustic waves may induce photo-elastic perturbations to optical waves in other cores as well. Such opto-mechanical coupling gives rise to inter-core cross-phase modulation effects, even when direct optical crosstalk is very weak. The cross-phase modulation spectrum reaches hundreds of megahertz frequencies. It may consist of discrete and narrow peaks, or may become quasi-continuous, depending on the geometric layout. The magnitude of the effect at the resonance frequencies is comparable with that of intra-core cross-phase modulation due to Kerr nonlinearity. Two potential applications are demonstrated: single-frequency opto-electronic oscillators that do not require radio-frequency electrical filters, and point-sensing of liquids outside the cladding of multi-core fibers, where light cannot reach.
Efficient phase to intensity conversion is key in Sagnac-loop based opto-electronic oscillators ( OEO). This paper features analytical modeling of phase to intensity conversion in practical ...Sagnac-loop interferometers, with practical coupling imbalance in 3-dB optical coupler, polarization imbalance of the non-reciprocal optical phase shifter (NRPS), and cross-talk ratio in polarization maintaining fiber (PMF). Single-sideband (SSB) phase noise of self-forced frequency stabilization technique of this OEO is also modelled using self-injection locked (SIL) and dual self-phase locked loop (DSPLL); the free-running and forced modeling results of Sagnac-loop based OEO matches with experimentally measured phase noise results. The measured phase noise of the SILDPLL based OEO at 10 GHz is −131 dBc/Hz at offset frequency of 10 kHz with approximately 11 dB phase noise reduction compared to the results of free-running OEO. Self-forced stabilization of OEO results in timing jitter of 19.5 fs, a factor of 6 times reduction in the free-running performance.
We experimentally demonstrate the generation and distribution of a microwave signal by using an optoelectronic oscillator. This system can be easily configured to generate microwave signals tuned ...over a very broad frequency range by selecting an appropriate optical delay. Experimental results show a good signal-to-noise-ratio at 4.1GHz.
We present our recent results on the development of low-noise photonic RF oscillators as well as single sideband electro-optic modulators/mixers enabling novel photonic transmitters and receivers ...suitable for microwave applications, including phased array systems. In particular, we report on the study and the performance of an all-dielectric RF photonic receiver based on optical whispering gallery mode (WGM) resonator technology. We also discuss ultra-compact power-efficient opto-electronic oscillators based on high-Q WGM resonators. These devices, suitable for applications in systems requiring small size, weight, and power (SWaP), operate in a broad frequency range generating spectrally pure RF signals characterized with record low phase noise. An example of a tiny radar transmitter and receiver based on this technology is described.
We experimentally demonstrate a multimode optoelectronic oscillator at 2.4 GHz with phase noise of −104.6 dBc/Hz at 100 KHz offset and an RMS jitter of 12.19 ps.
A hybrid-integrated frequency-locked loop is presented where an opto-electronic oscillator with a dispersive optical delay line is used to directly frequency lock a semiconductor laser to an RF ...synthesized source. A tracking range of 4.1 pm at a total power consumption of 33 mW is achieved.
Forced opto-electronic oscillators (OEO) are important component in future telecommunications and instrumentation systems. Most OEO are realized using intensity modulators (IM) with recent interest ...shifting to phase modulators (PM). A comprehensive analysis of Sagnac loop based OEO is presented, where phase is converted to intensity (PM-IM). This paper evaluates phase noise performance of SILPLL OEO in terms of Sagnac loop component errors and its impact on the PM-IM conversion. Results are presented for a 10 GHz SILPLL based OEO.
We present our recent results related to the development of ultra-compact opto-electronic oscillators based on high-Q whispering gallery mode (WGM) resonators. These oscillators operate in X-, Ku-, ...and Ka-bands and are able to generate spectrally pure RF signals characterized with less than -120 dBc/Hz phase noise at 100 kHz. The floor of the phase noise (<; -140 dBc/Hz) is limited by the shot noise of the signal received at the photodiode. Both tunable and fixed frequency oscillators are demonstrated.
Stable microwave oscillators are realized based on high quality factor resonators, which in turn are realized using acoustic, electromagnetic, and optical technologies. Since a large quality factor ...could be achieved using small and long fiber delay lines, optical techniques are particularly attractive. Among various techniques, opto-electronic oscillators (OEOs) have demonstrated the lowest close-to-carrier phase noise compared to all other techniques. Nevertheless, the temperature sensitivity of OEOs is of concern due to changes in the index of refraction of optical fibers. This paper provides results regarding the performance of an OEO at 10 GHz and performance comparison is made in using both standard (SMF-28) and solid-core photonic crystal fiber (SC-PCF). The OEO using SC-PCF fiber delay lines exhibits a factor of three reductions in its temperature sensitivity over SMF-28 based OEO
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