Analysis of the frequency characteristics of the spin-injection emitter in the terahertz range using a diffraction grating

A method for the measurement and identification of the radiation frequencies of the spin-injection oscillator in the terahertz frequency range using a diffraction grating is developed and experimentally implemented. For the system consisting of a ferromagnetic rod (Fe) and nanosized ferromagnetic film (Fe₃O₄ with a thickness of up to 100 nm), the thermal and dynamic components of the radiation that is induced by the current flow are separated. The diffraction peaks at a frequency of about 9.6 THz and a band of 37% at a level of 3 dB and at a frequency of 43.5 THz are demonstrated. It is shown that the intensity of each signal is significantly higher than the thermal background level.     

机抖式激光陀螺温度误差补偿研究

通过对激光陀螺机抖构件谐振频率和抖动幅值温度特性的分析，初步提出了利用稳幅、稳频控制等措施来改善系统性能的思想。基于两种温度模型的比较研究，给出了温度模型的选择准则，并对系统测试设备及温度试验等发表了相应的看法，指出了课题未来的发展方向。     

机抖式激光陀螺温度误差补偿研究

通过对激光陀螺机抖构件谐振频率和抖动幅值温度特性的分析,初步提出了利用稳幅、稳频控制等措施来改善系统性能的思想。基于两种温度模型的比较研究,给出了温度模型的选择准则,并对系统测试设备及温度试验等发表了相应的看法,指出了课题未来的发展方向。     

“偏频锁定”无调制的稳定激光器

本文介绍了一种无调制激光输出的“偏频锁定”稳频方法.文中对“偏频锁定”型激光器的工作原理、系统的主要部件及设计的考虑进行了较详细的描述.最后还给出了一台已用于碘稳定He-Ne激光器的“偏频锁定”稳频的实际电路.     

激光光热反射技术对薄膜热物性的表征

在考虑探测光束光斑尺寸对调制光热反射(MPR)信号影响的基础上,建立了三维的薄膜-衬底体系的激光光热反射理论模型。对利用激光光热反射技术测量薄膜热物性的可行性进行了研究,并对影响调制光热反射信号的材料参数进行了分析。此外,通过数值模拟研究了多参数拟合问题,即利用调制光热反射频响信号同时确定薄膜热扩散率、衬底热扩散率和界面热阻这三个物理参数。结果表明,与已有的径向扫描方法相比,频率扫描方法中的这三个参数之间并不存在高度的相关性,因此采用频响信号进行多参数拟合,可提高多参数拟合的收敛性和精确性。     

Millimeter-wave permittivity measurement of deposited dielectric films using the spherical open resonator

A differential method using the spherical open resonator is developed for permittivity measurement of a thin dielectric film on an optically dense substrate. It is based on a measurement of the resonant frequency shift due to the thin film on the substrate. The accuracy of the method is demonstrated to be about 4% for a 5.6-/spl mu/m photoresist film at 142 GHz.     

混合频率激光对CCD探测器损伤机理

为了进行对CCD探测器的损伤机理的探索研究,提出了采用双光束合成器件产生混合频率激光的原理与方法．利用Zemax软件模拟了双光束合成器件,同时对远场光斑进行了采集．基于热传导和热弹性力学的基本关系式建立了混合频率激光辐CCD探测器遮光铝膜层的热力耦合数学物理模型,对热传导方程和应力平衡方程进行了半解析求解,计算得到混合频率激光辐照CCD探测器的遮光铝膜层的瞬态温度场和环向热应力场,并通过数值仿真比较了不同工作模式激光光源对CCD的损伤效果．     

激光强回馈系统的动态调制稳频技术

激光强回馈系统与弱回馈系统相比,在无任何电子细分条件下就可获得纳米级的分辨率。但是,由于其回馈水平高,容易发生模式转换或偏振跳变,稳频十分困难。提出了一种激光强回馈系统的动态调制稳频方法,研究了动态调制稳频中的零点定位、清零补偿等关键技术及算法。实验结果表明,通过采用动态调制稳频技术,消除了激光强回馈系统中的模式转移及偏振跳变现象,获得了调制均匀、幅值相等的回馈条纹,有效地解决了激光强回馈系统的稳频问题,大大提高了系统的抗干扰能力,对进一步研究高精度强回馈测量系统具有重要意义。     

Using MZIs for Optical PSBT Transmissions: Requirements for Thermal Stabilization

In this paper, we discuss the quantification of Mach‐Zehnder interferometer (MZI) thermal stabilization which is needed in optical phase shaped binary transmission (PSBT) links. Considering the thermo‐optic and thermal expansion effects, we revisit the analytical expression for the thermal drift (GHz/°C) of the MZI center frequency (denoted here by the ‘MZI spectral drift’). An MZI is then used in an experimental transmission system using the optical PSBT format. We study the effect of spectral MZI drift by using a thermally stabilized interferometer and applying a frequency shift to the optical carrier. By using the thermal drift coefficient of the MZI, we find that to ensure low bit error rate fluctuations due to the MZI drift, the thermal stabilization of the device must have an accuracy of 0.5°C.     

利用Doppler展宽的Zeeman光谱实现钛宝石激光器的稳频

实现了一种可靠而又简单的用Doppler展宽的Zeeman光谱对连续单纵模钛宝石激光器进行稳频的方法.这种方法所需激光输出功率小于1 mW,激光器频率的长期稳定度小于1 MHz/h,且不受激光输出功率起伏的影响,频率锁定点可以在多谱勒展宽范围里随意调节.     

高分辨率光谱用的染料激光振荡放大系统

介绍一种用于高分辨率光谱的染料激光振荡放大系统,利用调Q的Nd:YAG激光器的二次谐波作泵浦光,使稳频连续染料激光输出获得放大,从而得到接近傅里叶变换极限的带宽及兆瓦级的峰功率。     

Switching-time limitation in tunable multisection lasers

The impact of the thermal transient on the frequency switching of multisection tunable lasers is studied. A simple thermal model is used to calculate the amplitude and time evolution of the frequency transient due to the thermal properties of both the laser chip and its mount. Transient time constants as large as 200 μs for the laser chip and several hundred milliseconds for the diode mount are measured, limiting the applicability of these devices to systems where the frequency is switched at low rates. A method to compensate electrically for this transient by means of a passive net work is demonstrated     

Frequency stabilization of semiconductor lasers for applications in coherent communication systems

The stabilization of the mean frequency of a single-mode semiconductor laser used under modulation in a FSK heterodyne transmission system is achieved by a novel method. The frequency stabilization scheme locks the laser to one of the resonance frequencies of a Fabry-Perot interferometer (FPI). The laser is weakly modulated at a frequency higher than any signal frequencies. Light reflected from the FPI is detected and synchronously demodulated for feedback and current control of the laser. A laser modulated by a pseudorandom sequence with a rate of 140 Mbit/s and an optical frequency deviation of 280 MHz is stabilized with this method against variations in operating temperature and bias current. The mean optical frequency is maintained within ± 10 MHz for hours. Analysis and experiments confirm that the laser frequency remains stable even when the laser linewidth changes under weak optical feedback.     

~(52)Cr原子束激光生荧光稳频技术

通过分析52Cr原子光刻对激光系统的技术要求,详细介绍了一种基于原子束激光感生荧光(LIF)光 谱技术的稳频方法。     

52Cr原子束激光生荧光稳频技术

通过分析^52Cr原子光刻对激光系统的技术要求，详细介绍了一种基于原子束激光感生荧光（LIF）光谱技术的稳频方法。     

13.5--Interferometric methods for measuring dispersion in CO2laser oscillations and amplifiers

An interferometric method is described for measuring the phase shifts caused by anomalous dispersion in laser active media under actual oscillating conditions. In addition, some data are presented which show how this method can be used to measure dispersion in a single-frequency 10.6-micron CO2laser plasma. The application of an interferometer of this kind to laser frequency stabilization is also discussed, and an absolute frequency stabilization scheme for CO2lasers is suggested. Because the phase shift observed is an antisymmetrical function about the center of the molecular resonance, it can be used directly as an absolute frequency control discriminant. The resulting frequency control system requires neither amplitude nor frequency modulation of the laser. A modification of a Mach-Zehnder interferometer for the measurement of dispersion in laser amplifiers is also described. This modified interferometer was used to measure phase shift as a function of frequency in an unsaturated traveling-wave CO2amplifier. The oscillographic data resulting from these measurements are shown.     

Laser diode frequency stabilization with a fiber ring resonator

To improve the frequency stabilization of laser diode in the laser frequency scanned interferometric metrology, a modified method is proposed by using a fiber ring resonator. The theoretical analysis of this modified method is performed. Moreover, the Pound-Drever-Hall (PDH) technique is employed to obtain the frequency discrimination curve of a fiber ring resonator, whose finesse is 1260 and line-width is 270 kHz. The simulated results show that the curve has a steep slope near the resonant frequency, which proves the sensitivity of this system to the frequency deviation, so the modified method has great potential for the frequency stabilization of a laser diode.     

基于比时法的晶振频率测量建模与分析

受器件老化、随机噪声等因素影响,晶振频率变化较复杂。以GPS秒脉冲作为测量标准,构建了晶振频率随时间变化的测量系统,通过对测量数据进行一元回归统计处理,分离出了晶振实际频率与其标称频率的相对偏差及晶振的各种随机误差,并分析了这两种误差对晶振准确度及稳定度的影响。该方法可为频率源误差测量分析提供借鉴作用。     

基于温度闭环反馈的He-Ne激光器热稳频系统

为了提升激光回馈测量系统中He-Ne激光器的性能, 解决激光回馈镜不断移动时频率无法使用传统方法稳定的技术问题, 采用基于温度反馈控制激光器管体温度的闭环被动稳频的方法, 进行了理论分析和实验验证, 研究了不同管体温度与环境温度差值下频率稳定性。结果表明, 系统最佳温差为25.6℃; 在此温差条件下稳频后, He-Ne激光器波长波动范围达10-4, 即频率稳定性达到1.61×10-7, 功率漂移量低于3.20%。该系统可以根据环境温度的变化调节稳频温度点, 并且稳频结构简单, 满足激光回馈一般应用系统稳定性的要求。     

用于原子重力仪的外腔半导体激光器的两种稳频方法比较

在铷原子气室中实现了饱和吸收谱稳频法和消多普勒的双色谱稳频法,以给在建的原子干涉重力仪系统选择合适的激光稳频方法。介绍了两种稳频方法的基本原理及实验细节。通过调整光路设计、自制低噪声光电探测器以及应用数字锁定模块,获得了良好的鉴频误差信号。每种方法都搭建了两套稳频系统并在3 000 s采集时间内保持锁定。激光器在经饱和吸收法和消多普勒双色谱法锁定后,激光频率波动分别为16.2 kHz和31.4 kHz,相应于在10 s采样时间下分别获得4.2110-11和8.1810-11的频率稳定度;相比之下,激光器自由运转时,频率波动和稳定度分别为629 kHz和1.6410-9。在原子重力仪系统小型化的需求下详述了两种稳频方法的优缺点,比较而得消多普勒的双色谱稳频法在原子干涉重力仪的小型化模块化发展方向不失为具有潜力的一种选择。