两段式DFB半导体激光器波长调谐实验研究

采用国产普通折射率耦合型两段式ＤＦＢ半导体激光器进行了波长调谐实验研究，实验结果表明，通过分别调节激光器两段的工作电流，不仅可以使器件单模工作，而且还能进行波长调谐。波长调谐范围为６．２ｎｍ，连续波长调谐范围为０．９ｎｍ。     

High Efficiency Flashlamps for Pulsed Dye Lasers

This paper discusses the possibilities of pulsed high pressure mercury capillary lamps as efficient pumping sources for dye lasers. Spectral measurements show that a spectral efficiency as high as 24 per cent may be reached for a typical blue lasing dye. Laser action has been obtained with Rhodamine 6G with a repetition rate of up to 100 p.p.s., and an experimental threshold in good agreement with the theoretical one, calculated from the spectra. The life of the lamps has been tested, and no reduction of the luminous output has been observed after ～10⁵ pulses. Severe thermal problems have been encountered with blue lasing dyes, which we hope to solve by using watersoluble coumarins.     

Linewidth-determining Processes in Distributed Feedback Dye Lasers

Abstract

Processes determining the linewidths of distributed feedback dye lasers (DFDL) have been investigated. Time resolution of the frequency of the output pulse shows that the linewidth, averaged over a pulse, arises predominantly from a dynamic sweeping of the laser frequency during the course of the pulse. This sweeping results from refractive-index changes in the dye over the duration of the pumping pulse; either through thermal effects or dispersion associated with the saturated gain. Thermal effects may be minimized by suitable choice of solvent but the dispersive sweep is inherent in this type of laser. The magnitude of the dispersive sweep changes across the tuning range of the laser. By judicious choice of dye solvent and dye parameters we have developed a narrow linewidth DFDL of 140 MHz for τ = 3·2 ns pulses, which is close to the transform limit.     

1.55μm InGaAsP-MQW自对准压缩台面高速DFB激光器

采用一种自对准压缩台面结构制作高速1.55μmDFB激光器。激光器的典型阈值为12mA，单面斜率效率达0．157mW/mA，出光功率大于20mW。由于采用窄条p-InP作为电流阻挡层，因此激光器的寄生电容可降至2.5pF,-3dB调制带宽可达9.1GHz。     

1.55 $mu$m InAs/InAlGaAs Quantum Dot DFB Lasers

For the fabrication of quantum dot (QD) distributed feedback (DFB) lasers, self-assembled InAs/InAlGaAs QDs were grown on the InP/InGaAs grating structures by a molecular beam epitaxy. Ridge-waveguide QD DFB lasers with a stripe width of 3 mum were fabricated. Single-mode lasing operation around the wavelength of 1.56 mum was successfully achieved under the pulsed and continuous-wave (CW) modes at room temperature. The lasing operation was also observed up to 70 degC under pulsed mode, which is the first observation on the single-mode lasing around 1.55 mum. The characteristic temperatures calculated from the temperature dependence of the threshold current density were 121.8 K from room temperature to 45 degC, which was reduced to 74.2 K from 45 degC to 70 degC.     

不同波长激光对计算全息位相光栅空间衍射光束分辨率的影响

针对用于激光阵列探测系统中的计算全息位相光栅，给出了在不同波长激光入射的情况下，衍射光束的空间分辨率随不同入射角的变化情况。用实验验证了用可见光代替红外激光进行初步测试与分析的可行性，为用于红外系统的整形光栅的测试提供了简捷，便利的实验方法。     

Holographic Beam-splitter in High Luminosity Holographic Recording

A holographic recording method in diffuse light is proposed. This method essentially allows to limit the losses of energy. In addition it is well adapted to the transmission and to the processing of holographic information by means of optic and electronic systems.     

Holographic stars

Holographic stars fabricated on DuPont's holographic recording film HRF 600X010 by the use of He-Ne laser light are demonstrated. The stars operate with plane waves, the transmitted portions of the input beams are used at the corresponding outputs, and the gratings are in the volume regime of diffraction. Multiple exposure based on the Bragg degeneracy effect is employed, which drastically reduces the number of multiplexed gratings and requires a three-dimensional arrangement of the replay beams.The star operates at different wavelengths only by the readjustment of the Bragg angles.     

Dynamic Range Enhancement for Pure Rotational Coherent Anti-Stokes Raman Scattering Thermometry by use of an Optical Arrangement with Two Dye Lasers

A disadvantage of pure rotational coherent anti-Stokes Raman scattering (CARS) compared with vibrational CARS is the limited dynamic range for temperature measurements. Here an optical configuration is described that overcomes this limitation by the use of two different center-frequency dye lasers in a dual-broadband CARS approach. Its performance is demonstrated for simultaneous pure rotational CARS temperature and relative N(2)-O(2)concentration measurements up to 1950 K at ambient pressure.     

Dynamic-single-mode Lasers

Recent progress in the dynamic-single-mode (DSM) semiconductor laser for long wavelength optical fibre communications is reviewed, and applications to wide-band optical fibre communication in the lowest loss wavelength region of 1·5–1·65 μm are studied. A DSM laser consists of a mode selective resonator and a transverse-mode-controlled waveguide, such as the narrow-striped distributed Bragg reflector (DBR) laser, to maintain a fixed axial mode under rapid direct modulation. The technology of monolithic integration for optical circuits is applied to realize some DSM lasers. The structures and properties of DSM lasers are reviewed.     

XUV Lasers

Abstract

Recent dramatic progress worldwide in the development of XUV lasers using laser-produced plasmas as the active media is reviewed, with particular reference to XUV lasers in recombining plasmas being developed by University groups in the U.K. using the SERC's Central Laser Facility.     

光缆CATV用DFB激光器发射组件

介绍了国内首次研制的光缆ＣＡＴＶ用１．３μｍＤＦＢ激光器组件。组件工作频带达到１ＧＨｚ，带内起伏〈１ｄＢ，组件的ＲＩＮ〈－１５３ｄＢ／Ｈｚ；出纤光功率〉２ｍＷ，载噪比ＣＮＲ〉５０ｄＢ。首次实现用低反射尖锥端光纤的ＤＦＢ激光器耦合。