Coherent beam combining(CBC)is an efficient way to scale the brightness of laser arrays.We demonstrate the active phase locking CBC of two slab laser amplifiers based on the multi-dithering technique.The experimental ...Coherent beam combining(CBC)is an efficient way to scale the brightness of laser arrays.We demonstrate the active phase locking CBC of two slab laser amplifiers based on the multi-dithering technique.The experimental investigation on the 102 W coherent beam combining of two slab amplifiers shows that the whole system in a closed loop performs well over a long time observation.The contrast of the coherent combined beam profile is about 87%and the combining efficiency is nearly 85%.In addition,the CBC of two green lasers is realized based on the second-harmonic generation of the phase locking pump lasers.To the best of our knowledge,this is the first report about second-harmonic active phase locking,which indicates further potential applications of CBC.展开更多
A low power low phase noise frequency synthesizer with subharmonic injection locking is proposed for ZigBee applications. The PLL is based on a ring VCO to decrease area and production cost. In order to improve phase ...A low power low phase noise frequency synthesizer with subharmonic injection locking is proposed for ZigBee applications. The PLL is based on a ring VCO to decrease area and production cost. In order to improve phase noise performance, a high frequency injection signal of which frequency varies with channel number is used. The circuit is designed in TSMC 0.18 μm CMOS technology and simulated in ADS (Advanced Design System). The phase noise at 3.5 and 10 MHz offsets is -116 and -118 dBc/Hz, respectively, and total circuit consumes 2.2 mA current.展开更多
In this paper the authors present an analysis and the implementation of microprocessor-baseddigital phase-locked loop speed control system for an induction motor which is actuated by aSPWM-GTR inverter.The system is c...In this paper the authors present an analysis and the implementation of microprocessor-baseddigital phase-locked loop speed control system for an induction motor which is actuated by aSPWM-GTR inverter.The system is controlled by a 16-bit single chip microprocessor.A new type of frequency and phase detector is presented in detail,An adaptive method isadopted in speed controller.A three mode control scheme is used.These techniques are very use-ful to the improvement of the dynamic behavior of digital AC motor drive system.Experimental results show that the system is of good stability,high precision and good dynam-ic performance.展开更多
Polarization fluctuation induced noise and backscattering-induced noise are the dominant noises in resonant fiber optic gyroscopes. This Letter proposes a new method to suppress the carrier and backscattering induced ...Polarization fluctuation induced noise and backscattering-induced noise are the dominant noises in resonant fiber optic gyroscopes. This Letter proposes a new method to suppress the carrier and backscattering induced noise by the sideband locking technique. Besides choosing an optimized modulation depth and different clockwise and counterclockwise modulation frequencies, the sideband is locked to the cavity resonance. With the proper modulation frequency, the carrier frequency component locates at a position far away from the resonant frequency, and then it is suppressed by the cavity itself, which can be taken as a bandpass filter. The amplitude of the carrier frequency can be suppressed by 20–25 d B additionally by the cavity and the total intensity suppression ratio can reach 115.74 d B. The backscattering induced noise can be eliminated for the adoption of different frequencies. The method can realize a stable and high suppression ratio without high requirements for parameter accuracy or device performance.展开更多
基金by the Innovation Foundation for Graduates in National University of Defense Technology under Grant B090704the Hunan Provincial Innovation Foundation For Postgraduate(No CX2009B006).
文摘Coherent beam combining(CBC)is an efficient way to scale the brightness of laser arrays.We demonstrate the active phase locking CBC of two slab laser amplifiers based on the multi-dithering technique.The experimental investigation on the 102 W coherent beam combining of two slab amplifiers shows that the whole system in a closed loop performs well over a long time observation.The contrast of the coherent combined beam profile is about 87%and the combining efficiency is nearly 85%.In addition,the CBC of two green lasers is realized based on the second-harmonic generation of the phase locking pump lasers.To the best of our knowledge,this is the first report about second-harmonic active phase locking,which indicates further potential applications of CBC.
文摘A low power low phase noise frequency synthesizer with subharmonic injection locking is proposed for ZigBee applications. The PLL is based on a ring VCO to decrease area and production cost. In order to improve phase noise performance, a high frequency injection signal of which frequency varies with channel number is used. The circuit is designed in TSMC 0.18 μm CMOS technology and simulated in ADS (Advanced Design System). The phase noise at 3.5 and 10 MHz offsets is -116 and -118 dBc/Hz, respectively, and total circuit consumes 2.2 mA current.
文摘In this paper the authors present an analysis and the implementation of microprocessor-baseddigital phase-locked loop speed control system for an induction motor which is actuated by aSPWM-GTR inverter.The system is controlled by a 16-bit single chip microprocessor.A new type of frequency and phase detector is presented in detail,An adaptive method isadopted in speed controller.A three mode control scheme is used.These techniques are very use-ful to the improvement of the dynamic behavior of digital AC motor drive system.Experimental results show that the system is of good stability,high precision and good dynam-ic performance.
文摘Polarization fluctuation induced noise and backscattering-induced noise are the dominant noises in resonant fiber optic gyroscopes. This Letter proposes a new method to suppress the carrier and backscattering induced noise by the sideband locking technique. Besides choosing an optimized modulation depth and different clockwise and counterclockwise modulation frequencies, the sideband is locked to the cavity resonance. With the proper modulation frequency, the carrier frequency component locates at a position far away from the resonant frequency, and then it is suppressed by the cavity itself, which can be taken as a bandpass filter. The amplitude of the carrier frequency can be suppressed by 20–25 d B additionally by the cavity and the total intensity suppression ratio can reach 115.74 d B. The backscattering induced noise can be eliminated for the adoption of different frequencies. The method can realize a stable and high suppression ratio without high requirements for parameter accuracy or device performance.
文摘目的:探讨Bite Turbo应用于自锁矫治技术中治疗青少年深覆牙合的效果。方法:纳入江门市新会区第二人民医院2020年1月至2021年1月期间收治的70例青少年深覆牙合患者作为研究对象,根据电脑生成随机数字表法分为两组,对照组35例给予3M自锁矫治器+平面导板治疗,观察组35例给予3M自锁矫治器+Bite Turbo治疗。观察并比较两组治疗后的颌骨改变情况及上颌牙齿位置与角度测量结果。结果:治疗后,两组的下齿槽座角(SNB角)、上齿槽座角(SNA角)、上下齿槽座角(ANB角)均较治疗前减小,且观察组均小于对照组(P<0.05)。治疗后,两组的Apg线至上中切牙切缘的垂直距离(Apg-U1距)、上中切牙缘至NA连线垂直距离(U1-NA距)、翼上颌裂后缘至上颌磨牙远中邻面垂直距离(Ptm-U6距)均较治疗前缩小,且观察组均小于对照组(P<0.05)。结论:在采用自锁矫治技术治疗青少年深覆牙合时,应用Bite Tur bo可有效改善牙齿形态,调整上颌牙齿的位置与角度。
