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Injection locking

About: Injection locking is a research topic. Over the lifetime, 4567 publications have been published within this topic receiving 60942 citations.


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01 Jan 2014
TL;DR: In this paper, the authors describe the design and investigation of a variation of printed resonators using Mobius slow-wave and Metamaterial structures for the applications in oscillator circuits.
Abstract: In modern information technology, increasingly powerful electronic circuits are required for the targeted generation of complex signals with well-defined amplitudes and phases. In circuits of this type, oscillators frequently form the central element because of its phase noise and stability, which essentially determines the achievable precision in the signal generation. Further requirements are derived from the electronic definability of the signal properties and the operational behavior of the oscillators. Conventional oscillator circuit models autonomous circuits, mainly consist of a passive frequency-selective or phase-selective network and an active amplifier element, which together produce an oscillatory circuit via a suitable feedback. At first glance, the circuit topology seems to be quite simple, and can often be explained quite visibly. However, when it comes to describing in particular the very important phase noise dynamics and stability of oscillators, it very soon becomes apparent that highly complex structures are involved. A fundamental difficulty in the theoretical description arises due to the non-linear behavior of oscillators, the understanding of which is crucial for a reliable description of jitter and oscillator phase noise. The resonant condition of oscillators arises due to the fact that the noise in the oscillator circuit is always present in the system, which is amplified in a frequency-selective manner to the extent that a stable oscillation arises at most at a fixed frequency because of non-linear limitation of the amplification. The frequency selectivity arises due to the frequency selectivity or phase selectivity of the passive feedback path. The non-linear limitation of the amplification in the oscillator normally results in a very reliable control of the amplitude noise of the output oscillation. It is well understood that any particular oscillator’s phase noise could be improved by increasing the generated signal amplitude or increasing the quality factor of the resonant network. Increasing the signal level is limited by the utilized supply voltage or the break down limits of transistors and cannot be increased further to improve the phase noise. Accordingly, the remaining phase noise, which can normally be minimized via resonating circuits with pronounced phase selectivity and therefore a high quality factor resonator, is of great importance for oscillators. Traditional high Q-factor resonators (ceramic resonator, surface acoustic wave, bulk acoustic wave, dielectric resonator, YIG resonator, Whispering gallery mode resonator, Optoelectronic resonator, etc.) are usually 3-dimensional structures and bulky for both handheld and test-measurement equipments and does not offer integration using current foundry technology. The current and later generation wireless communication market is pushing the need for miniaturization to its limits. Printed coupled transmission line resonator is a promising alternative due to its ease of integration and compatibility with planar fabrication processes but limited by its large physical size and low quality factor, making it a challenging choice to design low phase-noise oscillators. This problem is more prominent in integrated circuits (ICs) where high degrees of thin conductor losses reduce the quality factor by orders of magnitude compared to hybrid circuit technologies. This thesis describes the design and investigation of a variation of printed resonators using Mobius slow-wave and Metamaterial structures for the applications in oscillator circuits. A novel Mobius slow-wave mode-coupled structure offers additional degrees of freedom (higher Q-factor and multi-band characteristics for a given physical size) as compared to conventional transmission line printed resonators. A design study has been carried out to optimize the phase noise performance by using the novel resonant structures (mode-coupled, slow-wave, Mobius strips, evanescent mode, negative index material-Metamaterial) in conjunction with mode locking and injection locking for improving the overall performances, beyond the limits imposed by conventional limitations. The thesis also covers a broad spectrum of research on DRO and OEO ranging from practical aspects of circuit implementation and measurement, including the modeling of optical fiber delay line used as a thermally stable high Q-factor resonator structure. This thesis is research work carried out from 2004-2014, organized in 11 chapters, theoretical and experimental results documented by a range of specific measurement results and substantiated by over 200 scientific publications over dozen patents. The Metamaterial Mobius technology discussed in this thesis can open new era in the field of imaging, sensors, cloaking, energy harvesting and energy efficient microwave circuit and system Solutions.

20 citations

Journal ArticleDOI
TL;DR: It is shown that the low-frequency FN is completely suppressed by the optical injection, and the suppression bandwidth increases with the increasing injection ratio, and an additional peak in the FN spectrum is found, which can be higher than the carrier noise-induced one of free-running lasers.
Abstract: This work theoretically investigates the frequency noise (FN) characteristics of quantum cascade lasers subject to the optical injection through a set of coupled rate equations with Langevin noise sources. It is shown that the low-frequency FN is completely suppressed by the optical injection, and the suppression bandwidth increases with the increasing injection ratio. The optimal FN peak suppression ratio at an injection ratio of 10 dB reaches 2.9 dB. In addition, it is found that the optical injection at positive frequency detunings close to the locking boundary invokes an additional peak in the FN spectrum, which can be higher than the carrier noise-induced one of free-running lasers. This peak amplitude strongly depends on the value of the linewidth broadening factor. Unlike injection-locked interband lasers, the FN peak does not necessarily exhibit a resonance.

20 citations

Journal ArticleDOI
TL;DR: The experimental results demonstrate that optical injection can reduce the noise properties of the passively mode locked III-V/Si laser in terms of frequency linewidth and timing jitter, which makes the devices attractive for photonic analog-to-digital converters and clock generation and recovery.
Abstract: We demonstrate electrically pumped two-section mode locked quantum well lasers emitting at the L-band of telecommunication wavelength on silicon utilizing die to wafer bonding techniques. The mode locked lasers generate pulses at a repetition frequency of 30 GHz with signal to noise ratio above 30 dB and 1 mW average output power per facet. Optical injection-locking scheme was used to improve the noise properties of the pulse trains of passively mode-locked laser. The phases of the mode-locked frequency comb are shown to be coherent with that of the master continuous-wave (CW) laser. The radio-frequency (RF)-line-width is reduced from 7.6 MHz to 150 kHz under CW optical injection. The corresponding pulse-to-pulse jitter and integrated RMS jitter are 29.7 fs/cycle and 1.0 ps, respectively. The experimental results demonstrate that optical injection can reduce the noise properties of the passively mode locked III-V/Si laser in terms of frequency linewidth and timing jitter, which makes the devices attractive for photonic analog-to-digital converters and clock generation and recovery.

20 citations

Journal ArticleDOI
TL;DR: In this paper, a mutual injection-locked dual-wavelength single-longitudinal-mode fiber laser and an optoelectronic oscillator (OEO) were used to generate a stable and frequency-hopping-free microwave signal.
Abstract: We report a novel method to generate a stable and frequency-hopping-free microwave signal based on a mutually injection-locked dual-wavelength single-longitudinal-mode fiber laser and an optoelectronic oscillator (OEO), with the mutual injection locking realized by sharing an optical path consisting of a polarization modulator and a polarization-maintaining phase-shifted fiber Bragg grating. The two wavelengths from the fiber laser are injected into the OEO to lock the generated microwave signal, while the microwave signal from the OEO is fed back into the fiber laser to injection lock the two wavelengths. Thanks to the mutual injection locking, the operation stability of the fiber laser and the OEO are substantially improved. A microwave signal at 11.8 GHz with a phase noise of −105 dBc/Hz at a 10-kHz offset frequency is generated. A stable operation of the system without frequency shifting and hopping is demonstrated.

20 citations

Journal ArticleDOI
TL;DR: In this paper, a single far-field lobe and singlemode operation of a 20-element GaAlAs gain-guided coupledstripe array with 315 mW of output was obtained by injection locking with 3.9 mW incident power.
Abstract: Single far-field lobe and single-mode operation of a 20-element GaAlAs gain-guided coupled-stripe array with 315 mW of output was obtained by injection locking with 3.9 mW of incident power. The 0.31° lobe width was near the diffraction limit. An external small-signal gain of 19 dB was obtained.

20 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202333
202276
2021107
2020145
2019169
2018146