Energy scaling and extended tunability of a ring cavity terahertz parametric oscillator based on KTiOPO_4 crystal

A wide terahertz tuning range from 0.96 THz to 7.01 THz has been demonstrated based on ring-cavity THz wave parametric oscillator with a KTiOPO_4（KTP） crystal. The tuning range was observed intermittently from 0.96 THz to 1.87 THz,from 3.04 THz to 3.33 THz, from 4.17 THz to 4.48 THz, from 4.78 THz to 4.97 THz, from 5.125 THz to 5.168 THz, from5.44 THz to 5.97 THz, and from 6.74 THz to 7.01 THz. The dual-Stokes wavelengths resonance phenomena were observed in some certain tuning angle ranges. Through the theoretical analysis of the dispersion curve of the KTP crystal, the intermittent THz wave tuning range and dual-wavelength Stokes waves operation during angle tuning process were explained.The theoretical analysis was in good agreement with the experiment results. The maximum THz output voltage detected by Golay cell was 1.7 V at 5.7 THz under the pump energy of 210 mJ, corresponding to the THz wave output energy of5.47 μJ and conversion efficiency of 2.6 × 10^（-5）.

High power,widely tunable femtosecond MgO:PPLN optical parametric oscillator

We demonstrate a high power,widely tunable femtosecond MgO-doped periodically poled lithium niobate(MgO:PPLN)optical parametric oscillator(OPO)at 151 MHz,pumped by a Kerr-lens mode-locked Yb:KGW laser.With a maximum pump power of 7 W,the OPO is capable of delivering as high as 2.2 W of the signal centered around 1500 nm with tunable signal spectrum ranges of 1377 nm-1730 nm at an extraction efficiency of 31.4%,which exhibits a long-term passive power stability better than 0.71%rms over 4 h.The maximum idler bandwidths of 185 nm at 3613 nm are obtained across the idler tuning ranges of 2539 nm-4191 nm.By compensating intracavity dispersion,the signal has the shortest pulse duration of 170 fs at 1428 nm.

Start-Up Acceleration of Quartz Crystal Oscillator Using Active Inductance Double Resonance and Embedded Triggering Circuit

Low-frequency double-resonance quartz crystal oscillator was developed with active inductance circuit aiming the start-up of stable oscillation of tuning fork-type quartz crystal resonator at 32.768 kHz within 0.37 ms. The initial oscillation is triggered by a part of crystal oscillator forming a CR oscillator. The negative resistance ranges to 4 MΩ at gmf of 4.1 μA/V. In a limited frequency range, the circuit shows negative reactance Ccci = -3.4 pF equivalent to inductance Lcc = 9.8 H. The Allan standard deviation indicated 10-11 to 10-10, showing high stability comparable to general quartz crystal oscillator.

New design of high-precision oven controlled crystal oscillator

Combining oven controlled technique,digital compensation,high-resolution frequency difference measurement and self-calibration technique,a new design method of precise oven controlled crystal oscillator（OCXO） is proposed.Fine compensation is made in the vicinity of the crystal temperature inflection point by using the non-real-time temperature compensation strategy,and self-calibration system is integrated in the crystal.The method improves the digital compensated phase noise,simplifies the traditional OCXO development system,reduces the cost and shortens the developing cycle.Experiment results show that with a standard reference signal and self-calibration updated data,the oscillator can work stable and achieve its best performence.The performance index of crystal oscillator had an improvement with one to two orders of magnitude on the basis of original technical index.The method is widely used in the improvement of high-end crystal oscillator and atomic clock.

A 20MHz Low Phase-Noise 0.35μm CMOS Crystal Oscillator

The design procedure of a CMOS process integrating Colpitts cr ystal oscillator is described in detail by using the tools of Matlab and advanced design system (ADS). The small-signal analysis is performed both in the viewpoint of negative resistance and positive feedback. The analysis of condition for reliable start-up of oscillation and design guides for low phase noise is introduced. The measured phase noise is ?172dBc/Hz@10 kHz and the power dissipation is 0.36 mW at power supply 3V.

Fiber optical parametric oscillator based on photonic crystal fiber pumped with all-normal-dispersion mode-locked Yb:fiber laser

We demonstrate a cost effective, linearly tunable fiber optical parametric oscillator based on a home-made photonic crystal fiber pumped with a mode-locked ytterbium-doped fiber laser, providing linely tuning ranges from 1018 nm to 1038 nm for the idler wavelength and from 1097 nm to 1117 nm for the signal wavelength by tuning the pump wavelength and the cavity length. In order to obtain the desired fiber with a zero dispersion wavelength around 1060 rim, eight sam- ples of photonic crystal fibers with gradually changed structural parameters are fabricated for the reason that it is difficult to accurately customize the structural dimensions during fabrication. We verify the usability of the fabricated fiber experimen- tally via optical parametric generation and conclude a successful procedure of design, fabirication, and verification. A seed source of home-made all-normal-dispersion mode-locked ytterbium-doped fiber laser with 38.57 ps pulsewidth around the 1064 nm wavelength is used to pump the fiber optical parametric oscillator. The wide picosecond pulse pump laser enables a larger walk-off tolerance between the pump light and the oscillating light as well as a longer photonic crystal fiber of 20 m superior to the femtosecond pulse lasers, resulting in a larger parametric amplification and a lower threshold pump power of 15.8 dBm of the fiber optical parametric oscillator.

Interactions between Phospholipid Monolayers (DPPC and DMPC) and Anesthetic Isoflurane Observed by Quartz Crystal Oscillator

The interactions of phospholipid monolayers (dipalmitoyl phosphatidyl choline;DPPC and dimyristoyl phosphatidyl choline;DMPC) with volatile anesthetic isoflurane were investigated using quartz crystal microbalance (QCM) and quartz crystal impedance (QCI) methods. The quartz crystal oscillator was attached horizontally on the surface of DPPC and DMPC monolayer formed on the water surface. Physisorption of isoflurane hydrate at the DPPC monolayer surface was monitored in terms of frequency and resistance change of quartz crystal on addition of anesthetics isoflurane. Both frequency and resistance change showed the elastic nature of DPPC monolayer. Measurement of DMPC monolayer-isoflurane hydrate revealed the expandable nature of DMPC monolayer. Variation of frequency and impedance of DPPC and DMPC monolayer on addition of isoflurane which proved a two-step change has occurred at monolayer surface at isoflurane concentration of ≤8 mM that has been attributed to isoflurane aggregation at monolayer/water interface. Isoflurane hydrates formed in the process have capability to affect the interfacial properties of monolayer such as existence of structured water.

Reliability Design and Simulation of a Surface-Mount Temperature Compensation Crystal Oscillator

This paper introduces the structure and principle of a surface-mount high-precision temperature compensation crystal oscillator,and specifically describes the reliability design of a quartz-crystal resonator used inside the surface-mount temperature compensation crystal oscillator,the reliability design of surface-mount ceramic base and the reliability design of hybrid micro-assembly.Finally,the thermal and mechanical simulation results and the experimental verification of this surface-mount temperature compensation crystal oscillator are provided,which prove that this crystal oscillator has high reliability.

Theoretical Analysis and Computer Simulation of Different Balance Bridge Voltage Controlled Crystal Oscillator

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Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.

High efficiency continuous-wave tunable signal output of an intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

In this paper we report on a continuous-wave （CW） intracavity singly resonant optical parametric oscillator （ICSRO） based on periodically poled LiNbO3 （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects and diffraction loss, an optical ballast lens and a near-concentric cavity are adopted for better operation. Through varying the grating period and the temperature, the tunable signal output from 1406 nm to 1513 nm is obtained. At a PPLN grating period of 29 pm and a temperature of 413 K, a maximum signal output power of 820 mW at 1500 nm is achieved when the 808 nm pump power is 10.9 W, leading to an optical-to-optical conversion efficiency of 7.51%.

PAD Spectrometer Based on Wide Tunable Optical Parametric Oscillator for Noninvasive Medical Diagnostics

The gas analyzer based on optical parametric oscillators (OPO) and laser photo - acoustic spectroscopy is demonstrated. The optical parametric oscillators based on fun – out PPLN and bulk crystal AgGaS2 with a two-pass pumping are developed. Wide tunable OPO is pumped by compact nanosecond Nd: YLF laser. Pulse duration is 5 - 7 ns, maximum pulse energy is 1.5 mJ at a frequency of 100-2000 Hz. OPO lasing threshold is 10 - 16 mJ/cm2 at the spectral range 2.2 - 4 μm for fun – out PPLN OPO and 12 - 20 mJ/cm2 at the spectral range 4 - 7.5 μm for AgGaS2 OPO. Absorption spectra of gaseous mixtures (CH4, C3H8, C2H6, C2H4 and CO2) and human’s breath were studied.

A 515-nm laser-pumped idler-resonant femtosecond BiB_(3)O_(6) optical parametric oscillator

We report on an idler-resonant femtosecond optical parametrical oscillator(OPO)based on BiB_(3)O_(6)(BiBO)crystal,synchronously pumped by a frequency-doubled,mode-locked Yb:KGW laser at 515 nm.The idler wavelengths of OPO can be tuned from 1100 nm to 1540 nm.At a repetition rate of 75.5 MHz,the OPO generates as much as 400 mW of idler power with 3.1 W of pump power,the corresponding pulse duration is 80 fs,which is 1.04 times of Fourier transform-limited(FTL)pulse duration at 1305 nm.In addition,the OPO exhibits excellent beam quality with M^(2)<1.8 at 1150 nm.To the best of our knowledge,this is the first idler-resonant femtosecond OPO pumped by 515 nm.

一种基于相位误差校正技术的快速启动晶体振荡器

随着超低功耗(Ultra-Low Power,ULP)物联网(Internet of Things,IoT)系统的发展,采用能量注入技术的快速启动晶体振荡器因对IoT系统功耗影响巨大而逐渐成为研究热点.能量注入技术可以显著降低晶体振荡器的启动时间和启动能量,但是对注入源的精度要求苛刻.为了扩大注入频偏容限以及实现高注入效率,本文提出了一种基于延迟锁定环的相位误差校正技术.该技术将注入频偏容限扩大到2%,启动过程的非注入持续时间仅为4个周期,实现了高效注入.本文所述晶体振荡器采用40 nm CMOS工艺设计并流片.在1.0 V电源电压下采用24 MHz晶体进行测试,当注入频偏高达2%时,实现了7.2μs的启动时间,启动能量为5.1 nJ.相比同频偏下的传统注入方案,启动时间缩短了99.66%.

基于驯服钟控技术的时间频率源设计

标准时间频率信号是系统高效工作的基石,越来越高的时间频率测量精度对时频信号的产生提出了高稳定高准确度的要求。介绍了时间频率源的基本概念,阐述了一种基于驯服钟控技术的高稳定度高准确度时间频率源的基本工作原理及其设计,其输出的频率信号短期稳定度可达1.46×10-13/s。该设计方案已经成功应用于多个车载测控通信系统。

锂离子电池用正极材料LiCo_(1-x)Ni_xO_2的研究

采用高温法合成了ＬｉＣｏ１－ｘＮｉｘＯ２（ｘ＝０．２，０．５，０．８和１）。通过ＸＲＤ测定了它的晶格结构和晶胞参数。结果发现，随着ｘ值的增大，ａ０值和ｃ０值都顺次变大，ｘ＝１时晶胞体积最大。初步探索了ＬｉＣｏ１－ｘＮｉｘＯ２在１ｍｏｌ／ＬＬｉＣｌＯ４－ＰＣ＋ＤＭＥ中的充放电性能，典型样品在ＡＡ型锂离子电池中放电容量５００ｍＡｈ，０．２Ｃ充放循环了３００次。

新型VCOCXO控温原理及实现方法研究

提出了VCOCXO的一种新型控温方法 ,论述了其控温原理及实现 .从而研制成频率温度稳定度达到± 1× 10 -8( - 40～ 70℃ ) ,体积为 2 5mm× 2 5mm×

恒温晶振(OCXO)计算机辅助调试和自动测试系统

介绍恒温晶振 (OCXO)调试和测试的基本原理 ,讨论 OCXO计算机辅助调试和自动测试系统的设计要点和关键技术 ,包括系统功能与结构 ,软、硬件设计要点等。该系统已投入实际使用 。

微机控制OCXO测温电路的设计与分析

论述了一种采用热敏电阻电桥和高精密、低温飘、低功耗的运算放大器为微机控制OCXO设计测温电路的方法,并从多个角度对电路进行了深入透彻的分析。实验表明,这种测温电路结构简单、测温精度高、控温稳定性好。

EXO3晶振与KSS晶振在高过载下的失效特性分析

为了研究芯片抗高过载能力,本实验选取两种典型晶振芯片:EXO3、KSS,利用Hopkinson杆对其进行高g值冲击,以一维应力波理论估计芯片受到的加速度,并用运力学模型对其内部结构进行分析。结果表明:晶振的内部结构直接影响它的抗冲击性能;与应力波传播方向平行放置的晶振抗冲击性能要高于与应力波传播方向垂直的晶振。