Dispersion measurement technique based on the self-seeding laser oscillation of a Fabry-Perot laser diode

A simple dispersion measurement technique has been proposed and demonstrated by using the self-seeding laser oscillation of a Fabry-Perot laser diode through an optical closed-loop path. When the multi-mode optical pulses emitted from the laser are re-injected into the laser after traversing a fiber-under-test, a single mode laser oscillation occurs through the closed-loop path due to the group velocity difference between the pulses of different wavelengths. We measured the dispersion parameter of the fiber-under-test from the modulation frequency changes required to induce single-mode laser oscillations through the optical closed-loop path. The maximum measurement error was less than 1.5% for the optical fibers as compared with a commercial instrument.     

The role of nonlinear diode laser amplifiers in optical processors and interconnects

The advantages to be gained from the use of optical processors and interconnects for hybrid electronic/optical signal processing networks are first presented. The physics of nonlinear diode laser amplifiers is then examined in the context of optical thresholding and logic. Specific examples of the use of these devices in simple optical processors and interconnects are proposed. The technology required for realization of arrays of laser amplifiers for the proposed applications is finally discussed.     

The use of discharge electric field variations to CO2 laser stabilization

A method is described for detection of CO₂ laser power variations which requires no optical detector. It is based on electric field changes near the laser tube induced by the laser power fluctuations within the optical cavity. This phenomenon called by us “antenna effect” is used for laser stabilization. A simple and inexpensive technique for CO₂ laser power measurements, resonator adjustment, and for observation of the laser signature is described.     

Analysis of Center Wavelength Shift of VCSEL Light in AWG for WDM PON Applications

Center wavelength shift of vertical cavity surface emitting laser light in arrayed waveguide gratings is verified with mathematical and experimental analysis.It is induced by the linearly increasing trend of optical power of vertical cavity surface emitting laser by bias current increase.It is retrieved effectively to the original center wavelength by simple correction method of compensation.This was done for application of vertical cavity surface emitting laser as a light source in optical line terminal of wavelength division multiplexing-passive optical network.     

A simple model of laser-induced fluorescence under arbitrary optical thickness conditions at the excitation wavelength

A simple model is worked out to investigate laser-induced fluorescence in media of arbitrary optical thicknesses at the excitation wavelength. Close-form expressions are obtained for laser fluence, absorbed energy density and emitted fluorescence signal as a function of optical thickness and incident laser fluence. It is shown that in optically thick media saturation curves are not proportional to density of the species excited by the laser, except at saturation, and that the saturation fluence increases with optical thickness. Experimental saturation curves of lead in laser-produced plasmas of brass are discussed in the light of this model.     

High-power single-mode emission from a broad-area semiconductor laser with a pseudoexternal cavity and a Fabry Perot etalon

A simple pseudoexternal cavity with a commerically available broad-area laser diode, standard optics, and a thin FabryPerot etalon provides single-mode emission with 1-W optical power and a tuning range of ~0.5nm . The linewidth is estimated at 200MHz. Such high-power semiconductor laser systems are promising light sources for atomic physics, in which narrow-band high-power light is necessary, for example, for optical pumping of alkali metal vapor. Methods for expanding the tuning range and achieving higher narrow-band optical power are discussed.     

单模光纤共焦扫描显微系统研究

本文探讨一种使用单模光纤同时作为点源与点探测器的激光共焦扫描显微系统。该系统具有与传统共焦扫描相同的功能，但更容易操作，结构更简单，系统更稳定，文中给出系统的原理设计方案，并对其光学特性进行分析。     

用于飞秒紫外激光产生的LD泵浦高效Nd∶YVO_4绿光激光器研究

利用简单的折叠腔 ,腔内不含任何其它附加光学元件 ,LD双端泵浦 Nd∶YVO4 ,KTP腔内倍频绿光激光器实现了低阈值、高效率的 TEM0 0 模稳定激光输出 .最高绿光输出功率可达到 3 .3 W,光 -光转换效率为 1 6.2 % .     

A new optical method for the detection of in-plane motion of ultrasound propagating in metals

This paper describes a laser optical technique for the detection of in-plane (IP) motion of ultrasonic waves propagating in solids. This interference-based laser optical technique includes a tiny square indentation with a width of about 30 microm on the sample surface and a relatively simple optical arrangement. The current technique is applied for the detection of in-plane motions of Lamb waves propagating in a thin brass plate. Measurement of S(0) mode dominated by in-plane motion in the low fd (frequency times thickness) regime is successfully demonstrated with the current technique. The newly proposed non-contact technique provides an alternative other than the heterodyne and Fabry-Perot techniques for the detection of IP motions with a relatively simple optical arrangement. This technique is not readily applicable to general NDE applications, where a position scan or an arbitrary selection of inspection location is needed. However, this technique can be useful in the areas such as fixed-position ultrasound monitoring or laboratory research activities involving optical detection of IP motion.     

Cesium vapor laser with transverse pumping by multiple laser diode arrays

We have demonstrated a Cs vapor laser that utilizes fifteen laser diode arrays for transverse pumping of the gain medium. A maximum output power of 28 W was achieved with a total optical to optical efficiency of 14% and a slope efficiency of 15%. Transverse pumping allows scaling of such a laser system to a higher power level by simple increasing of the gain medium volume and the number of pump sources.     

Simple laser frequency locking based on Doppler-free magnetically induced dichroism

We present a simple and reliable optical setup for active stabilization of a diode laser. The method combines Doppler-free spectroscopy and magnetically induced dichroism in atomic vapor. The long- and short-term stability is achieved using a simplified optical and laser setup. We apply the setup to stabilize an external-cavity diode laser to the D2 atomic resonance in potassium vapor. With the laser locked we attain long-term stabilization to the atomic line with the reduction of laser frequency jitter down to 0.5 MHz on a 50 ms timescale.     

固体激光光折变自适应光外差探测技术研究

依据光折变晶体中自抽运与互抽运相位共轭共存的特性，提出了一种新型的光折变自适应光外差探测系统，并利用相干性较差的固体激光器进行了自适应光外差探测的实验研究。该系统具有结构简单、干扰和外差探测灵敏度高等优点，在光通信、激光雷达等许多领域内都具有重要的实用价值。     

Dynamics of laser-induced shock wave by optical probe in air

A new simple optical system based on optical beam deflection combining the holophote corner cube was developed in order to study the dynamics of laser-induced shock waves in air. In this method, we adopt a He-Ne laser beam as the detection beam. The He-Ne laser beam, reflected by corner cube, intersects the propagating shock wave at two successive positions. The measurement of the shock wave velocity benefits from the double peak signals induced by the same acting laser pulse, which is calculated from the time interval between the corresponding oscilloscope signals and the distance of the two He-Ne laser beams. By virtue of this setup, we are also able to determine the pressure of the generated shock waves. It is shown that this method is simple with a fairly good precision and is much easier than the conventional methods used for this task.     

Design of wavelength adjustable lasers with photonic crystal based Fabry-Perot etalon for applications in optical network units of wavelength-division-multiplexed passive optical network systems

We propose a novel wavelength adjustable laser (WAL) with a photonic crystal based Fabry-Perot (FP) etalon. This laser will be a promising light source for optical network units (ONUs) of conventional wavelength-division-multiplexed passive optical network (WDM-PON) systems for up-stream transmission. It has the merits of a relatively simple fabrication and operation, wide process tolerance, low-cost, high side-mode suppression ratio, and wavelength-tunable characteristics. The optimization of the device structure and the implementation methods for this type of laser are discussed. Although the WALs in WDM-PON systems are not colorless, each laser can cover several wavelengths. Thus, the required number of different ONUs can be reduced. This approach may be necessary for 10 Gbps upstream transmission in next-generation optical access networks because the 10 Gbps data rate is difficult to achieve by using current colorless schemes.     

A simple interferometric MTF instrument

A simple laser interferometric technique for measuring the modulation transfer function of an optical system is described.     

A 10-Hz terawatt class Ti:sapphire laser system: Development and applications

We developed a two-stage Ti:sapphire laser system to generate 16 mJ/80 fs laser pulses at a pulse repetition rate of 10 Hz. The key deriver for the present design is implementing a highly efficient symmetric confocal pre-amplifier and employing a simple, inexpensive synchronization scheme relying only on a commercial digital delay generator. We characterized the amplified pulses in spatial, spectral and temporal domains. The laser system was used to investigate various nonlinear optical processes, and to modify the optical properties of metal and semiconductor surfaces. We are currently building a third amplifier to boost the laser power to the multi-terawatt range.     

Long-external-cavity distributed Bragg reflector laser with subkilohertz intrinsic linewidth

We report on a simple, compact, and robust 780 nm distributed Bragg reflector laser with subkilohertz intrinsic linewidth. An external cavity with optical path length of 3.6 m, implemented with an optical fiber, reduces the laser frequency noise by several orders of magnitude. At frequencies above 100 kHz the frequency noise spectral density is reduced by over 33 dB, resulting in an intrinsic Lorentzian linewidth of 300 Hz. The remaining low-frequency noise is easily removed by stabilization to an external reference cavity. We further characterize the influence of feedback power and current variation on the intrinsic linewidth. The system is suitable for experiments requiring a tunable laser with narrow linewidth and low high-frequency noise, such as coherent optical communication, optical clocks, and cavity QED experiments.     

简易自相关仪对飞秒激光脉冲宽度的测量

用自制的简易自相关仪测量了飞秒的光脉冲宽度,测量结果与理论结果基本一致,并在此基础上分析了一些实验中的光学器件对飞秒激光脉冲宽度的影响.     

热分解法制备Bi替石榴石磁光薄膜的静态热磁模拟近似计算

对磁光薄膜进行热磁模拟可以了解影响热磁记录过程的各种因素及这些因素间的相互关系以及它们对写入信息的影响。采用近似计算方法对Bi、Al替DyIG磁光薄膜进行静态热磁模拟,得出在居里点写入的情况下写入点半径与定入功率、数值孔径、材料的反射率、材料的热导率及激光波长的关系。该方法为热磁定入过程提供了一种简捷的理论指导。