信道化声光外差频谱分析仪

为准确探测射频信号中所携带的全部信息，包括信号的幅度，频率和相位等，并有效地增加探测系统的动态范围，采用信道化体皮声光外差探测方法，这里给出这种体声光外左接收机的基本原理，光路设计的基本方法以及实验样机的测试结果。     

空间积分声相关处理的研究

利用声光布拉格器件成功地设计并研制出了空间积分声光相关器,实现了对模拟雷达信号（占空比为５０％,重复频率１ＭＨｚ,载频为１４０ＭＨｚ）的空间积分声光相关检测。     

激光二极管端面泵浦的调Q内腔倍频Nd：YAG激光器

报道了用两个１．５Ｗ激光二极管偏振耦合端面泵浦的声光调Ｑ内腔倍频Ｎｄ：ＹＡＧ激光器。输出５３２ｎｍ绿光重复频率１ＫＨｚ时，最大峰值功率为２．２３ＫＷ，最窄脉宽为１８ｎｓ，平均功率４０ｍＷ。最高重复频率３０ＫＨｚ。重复频率１５ｋＨＺ时，最高平均率１２８ｍＷ。对声光调Ｑ内倍频Ｎｄ：ＹＡＧ激光器的动态特性进行了理论分析及计算。     

射频激励双通道不等长电极波导CO2激光器的外频率调制研究

报道了采用不等长电极结构的射频激励双通道波导ＣＯ２激光器,通过调节射频电源功率的方法可以调谐双通道输出激光的外差频率,其调谐率约为０．１ＭＨｚ／Ｗ。在未采取任何措施时,其短期外差频率稳定性可达１０＾－１０。还在理论上分析了射频功率调谐外差频率的原理。     

1.319μm连续固体锁模激光器

报道了１．３１９μｍＮｄ：ＹＡＧ连续锁模激光器的技术研究。激光器的谐振腔为低热敏腔，用声光振幅调制器作为锁模元件，泵浦腔具有较高的泵浦效率和输出稳定性，获得了重复频率１００ＭＨｚ，平均功率～０．５４Ｗ，脉宽＜１７０ｐｓ的光脉冲。     

集成光学声光可调谐波长滤波器的研制

阐述了中心波长为１．５２３μｍ的集成光学声光可调谐波长滤波器的各项理论参数、制作工艺以及性能测试。在有效声光相互作用长度１６ｍｍ、射频驱动功率３５ｍＷ时,获得了模式转换效率大于９９％、插入损耗小于－４．ｄＢ、带宽１．６ｎｍ、３ｄＢ调谐范围为１４０ｎｍ的实验结果。     

双KTP内腔参量下转换产生量子相关孪生光子对

使用双ＫＴＰ晶体串接，经光学参量振荡腔内参量下转换，在３００ｍＷ泵浦功率下，获得总功率约２３ｍＷ的强度相关的孪生光束，在１．２５ＭＨｚ处其强度差噪声功率较散离噪声极限降低５０％（３ｄＢ）。     

声光偏转效应在相干光检测的应用

为使现代电子侦察技术能适应信号密集、宽频谱、大动态的电磁环境, 提出了一种基于声光偏转器实现相关光信号处理的方法, 分析了射频信号频率变化与布拉格衍射角的关系, 讨论了声光偏转效应对信号频率的空间滤波特性; 在理论分析的基础上, 构建了在可见光范围内实现声光偏转的相干光信号探测的实验系统, 并通过计算机仿真对比, 验证了这种方法的可行性。实验表明, 采用波长为630 nm的单频激光, 带宽为200 MHz的声光偏转器, 其频率分辨率优于1 MHz, 频率信号的空间分离效果明显, 接收灵敏度和信噪比得到改善。     

单频运转的Nd：YVO4激光器

报道了激光二极管纵向泵浦单频运转的Ｎｄ：ＹＶＯ４激光器，用波长为８０９ｎｍ激光二极管的连续输出功率６６０ｍＷ泵浦，获得１０６４ｎｍ，功率为１５５ｍＷ连续单频输出，泵浦阈值２２６ｍＷ，斜率效率３３．８％，线宽小于１０ＭＨｚ．     

1.5μm波导声光可调滤光器研究

对１．５μｍ波导型声光ＴＥ－ＴＭ模式转换光滤波器进行了研究。采用了可降低驱动功率的表面声波导结构。在１．５￣１．６μｍ波段实现了可调滤光，通带宽度小于２ｎｍ，达到９７￥以上转换率所需的射频驱动功率约８０ｍＷ（１９ｄＢｍ），器件总插入损耗约９ｄＢ。     

Development of an optical fiber hydrophone with fiber Bragg grating

A new type of optical fiber hydrophone is constructed with a fiber Bragg grating (FBG) based on the intensity modulation of laser light in an FBG under the influence of sound pressure. The FBG hydrophone shows linearity, with dynamic range about 70 dB. It can measure amplitude and phase of an acoustic field in real time, and operates in a wide range of acoustic frequency, at least from 1 kHz to 3 MHz. No signal distortion is observed in the detected signal. Because of the simplicity in its operating principle and geometry, an FBG hydrophone is expected to be an acoustic sensor of high practicality compared to a conventional optical fiber hydrophone.     

Wide-bandwidth 25-dB amplitude noise suppression in a pump-and-signal-resonant optical parametric oscillator

We present a pump-and-signal-resonant optical parametric oscillator that provides 25 dB of amplitude noise suppression of the transmitted pump beam from dc to 20 kHz. The upper frequency range of the optical limiter increases as the pump power is increased, up to 1 MHz with 580 mW of input power. The amount of noise suppression is limited by pump-depletion effects. The upper frequency range is limited by the temporal response of the device. We present a numerical analysis that predicts this behavior.     

Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure

We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.     

Non-Gaussian statistics and temporal variations of the ultrasound signal backscattered by blood at frequencies between 10 and 58 MHz

Very little is known about the blood backscattering behavior and signal statistics following flow stoppage at frequencies higher than 10 MHz. Measurements of the radio frequency (rf) signals backscattered by normal human blood (hematocrit = 40%, temperature = 37 degrees C) were performed in a tube flow model at mean frequencies varying between 10 and 58 MHz. The range of increase of the backscattered power during red blood cell (RBC) rouleau formation was close to 15 dB at 10 and 36 MHz, and dropped, for the same blood samples, below 8 dB at 58 MHz. Increasing the frequency from 10 to 58 MHz raised the slope of the power changes at the beginning of the kinetics of aggregation, and could emphasize the non-Gaussian behavior of the rf signals interpreted in terms of the K and Nakagami statistical models. At 36 and 58 MHz, significant increases of the kurtosis coefficient, and significant reductions of the Nakagami parameter were noted during the first 30 s of flow stoppage. In conclusion, increasing the transducer frequency reduced the magnitude of the backscattered power changes attributed to the phenomenon of RBC aggregation, but improved the detection of rapid growth in aggregate sizes and non-Gaussian statistical behavior.     

Underwater Acoustic Sensor with Fiber Bragg Grating

A new type of underwater acoustic sensor is proposed with an optical fiber Bragg grating (FBG). Because of the photoelasticity with respect to the refractive index and the elasticity of the fiber, the sound pressure in water modulates the Bragg reflection wavelength and, in turn, the intensity of the laser light transmitted through the FBG fiber. Good linearity between the detected signal and the sound pressure is obtained in the range from 81 dB to 140 dB re 1 μPa. Since the upper and lower limits of the acoustic signal level for operation of the sensor are limited by the driving circuit and the transduction of the sound in water, the sensor is expected to operate with much larger dynamic range both at higher and lower pressure levels. Operation of the sensor is very stable with the insertion of optical isolators into the system, although without the isolators the output signal fluctuates at low frequency due to the Fabry-Perot interference effect between the FBG and the various facets.     

Continuous radio-frequency tuning of an optoelectronic oscillator with dispersive feedback

We describe and demonstrate a novel technique for continuously tuning the frequency of a dual-loop-configuration optoelectronic rf oscillator. The rf tunability is obtained from a tunable diode laser and dispersive optical fibers. Results are presented for three ranges of frequency, centered at 550 MHz, 3 GHz, and 9 GHz. The frequency can be tuned electrically with constant rf power within a range of 0.1-1.9 MHz, depending on the center oscillation frequency. The tuning range can be increased eightfold through the use of highly dispersive fibers.     

光通信波段低频压缩态光场的实验制备

本文利用周期极化磷酸氧钛钾晶体构成的半整块结构简并光学参量振荡器实验制备了连续变量光通信波段低频压缩态光场。光学参量振荡器的阈值功率为210 mW。当775nm抽运光场功率为130 mW时,在分析频段50kHz~900kHz范围内获得真空压缩态光场。在200kHz分析频率处,压缩态光场的最大压缩度达5.0dB;在最低分析频率50kHz处,压缩态光场的压缩度为2.0dB。该低频压缩态光场可为基于光纤的量子精密测量提供量子光源。     

在热压缩态中测量相位算符的涨落

利用热场动力学的方法计算了热压缩态中测量相位算符的涨落，引入了两种类型的基础量子涨落，一种是与测量相位的两个正交分量相联系，另一种是与一个测量相位分量和光子数相联系。由此，研究了热压缩压中测量相位涨落的两种压缩及其与温度的关系。     

Spectral hole burning for wideband, high-resolution radio-frequency spectrum analysis

We present experimental results for what is to our knowledge the first spectral-hole-burning based rf spectrum analyzer to cover 10 GHz of rf analysis bandwidth. The rf signal of interest is modulated onto an optical carrier, and the resultant optical sidebands are burned into the inhomogeneously broadened absorption band of a Tm3+:YAG crystal. At the same time a second, frequency-swept laser reads out the absorption profile, which is a double-sideband replica of the rf spectrum, and thus the rf spectrum can be deduced after spectral calibration of the nonlinear readout chirp. This initial demonstration shows spectral analysis covering 10 GHz of bandwidth with >5500 spectral channels and provides 43 dB of dynamic range.