Modeling and experimental studies of a side band power re-injection locked magnetron

A side band power re-injection locked （SBPRIL） magnetron is presented in this paper. A tuning stub is placed between the external injection locked （EIL） magnetron and the circulator. Side band power of the EIL magnetron is reflected back to the magnetron. The reflected side band power is reused and pulled back to the central frequency. A phase-locking model is developed from circuit theory to explain the process of reuse of side band power in SBPRIL magnetron. Theoretical analysis proves that the side band power is pulled back to the central frequency of the SBPRIL magnetron, then the amplitude of the RF voltage increases and the phase noise performance is improved. Particle-in-cell （PIC） simulation of a 10-vane continuous wave （CW） magnetron model is presented. Computer simulation predicts that the frequency spectrum＇s peak of the SBPRIL magnetron has an increase of 3.25 dB compared with the free running magnetron. The phase noise performance at the side band offset reduces 12.05 dB for the SBPRIL magnetron. Besides, the SBPRIL magnetron experiment is presented. Experimental results show that the spectrum peak rises by 14.29% for SBPRIL magnetron compared with the free running magnetron. The phase noise reduces more than 25 dB at 45-kHz offset compared with the free running magnetron.

All-optical carrier recovery for self-homodyne detection via injection locked Brillouin laser in whispering-gallery-mode microcavity

We demonstrate comprehensive investigation of the injection locking dynamics of a backscattered Brillouin laser in silica whispering-gallery-mode microcavity. Via injection locking, the Brillouin laser acquires highly correlated phase with the seed laser, enabling ultra-narrow bandwidth, high gain, and coherent optical amplification. Also, for the first time,to the best of our knowledge, the injection locked Brillouin laser is utilized to implement all-optical carrier recovery from coherent optical data signals. We show that by using the injection locked Brillouin laser as a local oscillator for self-homodyne detection, high-quality data receiving can be realized, even without traditional electrical compensations for carrier frequency and phase drifts.

High-Power Simultaneous Wireless Information and Power Transfer: Injection-Locked Magnetron Technology

Applications using simultaneous wireless information and power transfer(SWIPT)have increased significantly.Wireless communication technologies can be combined with the Internet of Things to develop many innovative applications using SWIPT,which is mainly based on wireless energy harvesting from electromagnetic waves used in communications.Wireless power transfer that uses magnetrons has been developed for communication technologies.Injection-locked magnetrons that can be used to facilitate high-power SWIPT for several devices are reviewed in this paper.This new technology is expected to pave the way for promoting the application of SWIPT in a wide range of fields.

An injection-locking diode laser at 671 nm with a wide tuning range up to 6 GHz

We present a compact injection-locking diode laser module to generate 671 nm laser light with a high output power up to 150 m W.The module adopts a master-slave injection-locking scheme,and the injection-locking state is monitored using the transmission spectrum from a Fabry-Perot interferometer.Beat frequency spectrum measurement shows that the injection-locked slave laser has no other frequency components within the 150-MHz detection bandwidth.It is found that without additional electronic feedback,the slave laser can follow the master laser over a wide range of 6 GHz.All the elements of the module are commercially available,which favors fast construction of a complete 671-nm laser system for the preparation of cold^(6)Li atoms with only one research-grade diode laser as the seeding source.

Numerical study of converting beat-note signals of dual-frequency lasers to optical frequency combs by optical injection locking of semiconductor lasers

The optical injection locking of semiconductor lasers to dual-frequency lasers is studied by numerical simulations.The beat-note signals can be effectively transformed to optical frequency combs due to the effective four wave-mixing in the active semiconductor gain medium. The low-noise Gaussian-like pulse can be obtained by locking the relaxation oscillation and compensating the gain asymmetry. The simulations suggest that pulse trains of width below 30 ps and repetition rate in GHz frequency can be generated simply by the optical injection locking of semiconductor lasers. Since the optical injection locking can broaden the spectrum and amplify the optical power simultaneously, it can be a good initial stage for generating optical frequency combs from dual-frequency lasers by multi-stage of spectral broadening in nonlinear waveguides.

A power and wavelength detuning-dependent hysteresis loop in a single mode Fabry-Prot laser diode

In this paper, we observe experimentally the optical bistability induced by the side-mode injection power and wave- length detuning in a single mode Fabry-P6rot laser diode （SMFP-LD）. Results show that the bistability characteristics of the dominant and injected modes are strongly dependent on the injected input optical power and wavelength detuning in an SMFP-LD. We observe three types of hysteresis loops： counterclockwise, clockwise, and butterfly hysteresis with various loop widths. In the case of a bistability loop caused by injection power, the transition from counterclockwise to clockwise in the hysteresis direction with the wavelength detuning from 0.028 nm to 0.112 nm is observed in a way of butterfly hys- teresis for the dominant mode by increasing the wavelength detuning. The width of hysteresis loop, induced by wavelength detuning is also changed while the injection power is enhanced from -7 dBm to -5 dBm.

Intensity Noise Suppression of an FP Laser by External Injection Locking

The optimal intensity noise suppression of a Fabry-Perot （FP） laser is experimentally acquired by relatively strong external optical injection locking technology. The maximum suppression is up to 9dB around the relaxation oscillation peak of the free running FP laser. We demonstrate how the injection light power and detuning frequency influence the intensity noise suppression effects. Additionally, the relationship between the optimal suppression range and the stable locking range is experimentally studied：both ranges enlarge as the injection light power increases, but the stable locking range permits larger detuning frequency at identical injection light power.

Wavelength synchronization technology for UDWDM-PON transmitter based on injection locking

We propose a concept of wavelength synchronization to ensure the stability of ultra-dense channels in an ultra-dense wavelength division multiplexing passive optical network(UDWDM-PON)transmitter.A mode-locked laser is used to provide wavelength references for users.By injection locking the semiconductor laser,the separation of the wavelength reference is realized in an optical line terminal.The downlink and uplink wavelength references are interlaced and distributed to facilitate the synchronization of uplink carriers.In the optical network unit,the uplink optical carriers are filtered by injection locking semiconductor lasers,which achieve wavelength synchronization for the uplink users.In this Letter,an adaptive wavelength synchronization transmitter for UDWDM-PON is realized with a channel spacing of 5 GHz.

Low-noise amplification of dissipative Kerr soliton microcomb lines via optical injection locking lasers

The dissipative Kerr soliton microcomb provides a promising laser source for wavelength-division multiplexing(WDM)communication systems thanks to its compatibility with chip integration.However,the soliton microcomb commonly suffers from a low-power level due to the intrinsically limited energy conversion efficiency from the continuous-wave pump laser to ultra-short solitary pulses.Here,we exploit laser injection locking to amplify and equalize dissipative Kerr soliton comb lines,superior gain factor larger than 30 dB,and optical-signal-to-noise-ratio(OSNR)as high as 60 dB obtained experimentally,providing a potential pathway to constitute a high-power chip-integrated WDM laser source for optical communications.

Wide band low phase noise QVCO based on superharmonic injection locking

A wide band, injection-coupled LC quadrature voltage control oscillator is presented. In the proposed circuit, two oscillators are injection locked by coupling their second-order harmonics in anti-phase, forcing the outputs of two oscillators into a quadrature phase state. As the common-mode point sampling the second har- monic frequency, flicker noise of the tail current is suppressed, the phase noise is reduced .The proposed design accomplishes a wide tuning frequency range by a combination of using a 5-bit switch capacitor array （SCA） for discrete tuning in addition to linearly varying AMOS varactors for continuous tuning. The proposed design has been fabricated and verified in a 0.18/zm TSMC CMOS technology process. The measurement indicates that the quadrature voltage controlled oscillator has a 41.7% tuning range from 3.53 to 5.39 GHz. The measured phase noise is 127.98 dBc/Hz at 1 MHz offset at a 1.8 V supply voltage with a power consumption of 12 mW at a carrier frequency of 4.85 GHz.

Detection of DC electric forces with zeptonewton sensitivity by single-ion phonon laser

Detecting extremely small forces helps exploring new physics quantitatively.Here we demonstrate that the phonon laser made of a single trapped ^(40)Ca^(+) ion behaves as an exquisite sensor for small force measurement.We report our successful detection of small electric forces regarding the DC trapping potential with sensitivity of(2.41±0.49)zN/√Hz,with the ion only under Doppler cooling,based on the injection-locking of the oscillation phase of the phonon laser in addition to the classical squeezing applied to suppress the measurement uncertainty.We anticipate that such a single-ion sensor would reach a much better force detection sensitivity in the future once the trapping system is further improved and the fluorescence collection efficiency is further enhanced.