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.

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）.

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.

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。

晶体振荡器温度漂移测试系统的软件设计与实现

针对现有晶体振荡器的温度漂移检测方法在数据的获取和分析方面存在一定的局限性的问题,该文设计一款用于晶体振荡器的温度漂移测试系统。主要介绍了温度漂移检测工艺和硬件组成、上位机软件的设计与功能、晶体振荡器温度漂移检测自动控制方案。上位机软件基于VisualStudio.Net框架使用C#语言设计和编写,使用SQL Server搭建测试数据库。实际测试表明,上位机软件系统可以提高温度漂移检测效率,具备一定的实用性和可靠性。

极端环境下恒温晶体振荡器的传热过程仿真

晶体是恒温晶体振荡器的核心部件,需要保持温度恒定不变,外部环境温度的巨大变化必将影响晶振输出频率信号的稳定性。根据恒温晶体振荡器的工作状态和机制,建立其在稳态下传热过程的数学模型,探究晶体在高低温环境下的热稳定性,重点分析不同环境温度下功率管输出功率对晶体温度的影响,并利用恒温晶体振荡器实际运行过程中的数据进行验证。结果表明通过仿真得到的数据与实测数据基本一致,当环境温度分别为-40℃、25℃和70℃时,要使稳定后的晶体温度恒定为85℃,相应功率管稳定后的输出功率应为3.95 W、1.42 W和0.74 W。通过调节功率管的输出功率来使晶体在极端环境下达到预设温度并保持恒定,进而使晶振有较高的频率稳定度和较低的相位噪声水平,保证高精度的时钟信号输出。

Differential Operator Approach to■quantum Groups and Their Oscillator Representations

For a quasi-split Satake diagram,we define a modified q-Weyl algebra,and show that there is an algebra homomorphism between it and the corresponding■quantum group.In other words,we provide a differential operator approach to■quantum groups.Meanwhile,the oscillator representations of■quantum groups are obtained.The crystal basis of the irreducible subrepresentations of these oscillator representations are constructed.

小型化宽温高精度温补晶振的设计与实现

介绍了一种小型化宽温高精度温补晶振的设计方案及其补偿的实现。该设计的核心是采用专用温补芯片和分立结构实现产品的小型化和低功耗,并避免环境温度对补偿精度的干扰,保证温补晶振宽温高精度的实现。通过这种补偿方法研制的10 MHz温补晶振,在-55℃~+85℃范围内频率温度稳定度优于±0.28×10^(-6),相位噪声优于-150dBc/Hz@1kHz。测试结果表明,该温补晶振具有体积小,工作温度范围宽,功耗低和相位噪声特性良好等特点。同时该产品可靠性高,适合批量化生产,可广泛用于军民测控通讯类设备中。

基于GRU神经网络的恒温晶振频率漂移预测

恒温晶振作为新时代5G通信系统的重要器件,其频率稳定性相当重要,准确预测恒温晶振频率漂移可以提高系统工作状态的安全性与可靠性。为进一步提高频率漂移预测精度,满足5G通信系统需求,提出了一种基于门控循环单元(GRU)神经网络的晶振频率预测模型。该模型同时考虑温度、老化两种因素,并利用神经网络具有出色的自适应性与非线性泛化能力,学习恒温晶振频率漂移变化规律。最后以14 d实测数据为例进行研究分析,并与循环神经网络、长短时记忆神经网络做对比实验,以均方根误差、平均绝对误差、算法运行时间作为评价指标,结果表明GRU网络具有更高的预测精度、更快的运算速度。

基于卫星共视与载波通信的台区级时间溯源装置的实现

本文基于卫星共视与载波通信的台区级时间溯源装置,采用北斗卫星共视和晶振驯服技术,设计了一款低成本、小型化且高精度的时频设备,并对其性能进行验证。实验证明:该设备能有效提供高精度、可溯源的时间频率信号。