Singlemode passive Q-switched ruby laser

Results are reported on a passiveQ-switched ruby laser utilizing a special rooftop prism cavity. With a 40 cm long resonator, a single transverse and longitudinal mode has been obtained. With a 3 meter long resonator, a single transverse mode self-locked beam has been obtained.     

Energy losses in a passive Q-switched ruby laser

An experimental investigation has been performed in order to explain why the output energy from a ruby laser is always reduced when passing from normal laser operation toQ-switching operation. A saturable absorber was used as the switching element; however, the discussion about the energy losses is valid for everyQ-switching system. Experimental data allow one to evaluate the decrease of the output energy due to the reduced pumping efficiency, to the losses in the optical switch, and to the incomplete depletion of the inversion arising from the spatial inhomogeneity of the standing wave in the resonator and from the relaxation processes in the ruby line.     

高功率Q开关双脉冲红宝石激光器

本文叙述了双脉冲激光器的基本原理及调试方法，这个方法原则上可适用于其他类型KDP—Q开关高功率双脉冲激光器的研制（如钕玻璃，Nd：YAG双脉冲激光器）。     

基于CPLD设计实现单横单纵激光器种子注入纵模锁定

基于自滤波非稳腔、种子激光注入及CPLD控制的干涉法纵模锁定技术,研制出一套单横单纵激光器系统；对激光器的工作原理及纵模锁定电路设计进行了说明。该设计具有输出光束质量好,工作稳定,抗干扰性强的特点。该激光器经历了在强干扰环境中长时间的“烤机”实验,单纵模锁定概率达100%。     

A continuously pumped repetitively Q-switched ruby laser and applications to frequency-conversion experiments

A repetitivelyQ-switched ruby laser with 30-kW 30-ns pulses, suitable for many nonlinear optics experiments, is described. Using this laser SHG in KDP located outside the laser cavity yielded ≳ 4-kW pulses at 3472 Å with conversion efficiencies of ∼16 percent at the peak. A correction to existing SHG theories accounting for pump depletion (important at high conversions) has been calculated with the resulting improvement in agreement between theory and experiment. Experiments involving stimulated Raman scattering and vacuum UV generation from laser-produced plasmas are briefly described.     

Simple single longitudinal mode Q-switched Nd:YAG oscillator

A simple three-mirror resonator is considered for longitudinal mode control in a passivelyQ-switched Nd:YAG laser. This configuration provides temporally smooth output pulses with duration determined by dye concentration and continuously variable from 300 to 10 ns. Previous problems with spatial beam quality can be minimized by careful arrangement of cavity components.     

Single high-order transverse mode surface-emitting laser with controlled far-field pattern

Single transverse mode vertical-cavity surface-emitting lasers (VCSELs) with high output power are important for high-speed data links, optical recording, laser processing, and so on. We demonstrate a single high-order transverse mode VCSEL with narrow trenches formed on its top surface by using a focused ion beam. The formation of four straight cross trenches resulted in the selection of a stable LP/sub 41/ mode oscillation. A large far-field angle of the LP/sub 41/ mode, which causes a low coupling efficiency even with a multimode fiber, was drastically reduced by loading a phase shift layer. A single-lobe far-field pattern with low scattering loss was realized by loading a spatial phase shift of SiO/sub 2/. We evaluated a coupling efficiency with a single-mode fiber including its alignment tolerance. The controlled far-field pattern enables lens-free direct coupling with a single-mode fiber even for large active-area VCSELs.     

Amplification properties of a tunable single transverse mode laser diode

The amplification properties of a tunable single transverse mode laser diode can be exploited to be used as ann times 1wavelength division switch. This kind of switch is expected to play an important role in telecommunications systems, especially when signals are not synchronous or when signal bit rates are various. The light amplification ratio between a desired main-mode wavelength and undesired submode wavelengths are improved by decreasing injection light power, and a ratio of 8.5 dB is achieved. This experimental result is in good agreement with theory. It is predicted theoretically using rate equations that the ratio is also improved by increasing the laser cavity mirror loss difference between the main mode and the submodes. A light amplification ratio of more than 11 dB is obtained when the cavity mirror loss difference is more than 50 cm^-1.     

光纤激光器共腔法纵模选择技术

复合腔法光纤激光器谐振腔结构灵活,可以根据需要构成各种结构实现纵模选择.但稳定性差是制约其应用的主要原因,为提高光纤激光器纵模选择的稳定性及抗干扰能力,在复合腔基础上提出“共腔结构”光纤激光器这一概念.分别采用传输矩阵和自由光谱范围(FSR)两种方法详细分析了“共腔结构”光纤激光器的特性,理论分析证明:共腔结构可有效增...     

采用纵模匹配技术的短脉冲注入锁定染料激光器

本文报道了采用纵模匹配技术的短脉冲注入锁定染料激光器系统及实验结果.     

External cavity controlled single longitudinal mode laser transmitter module

A GaInAsP/InP laser transmitter module incorporating an external cavity is described. It is shown that the cavity produces stable tunable single longitudinal mode operation of the laser even under high speed modulation conditions.     

Single longitudinal mode operation of the electron-beam-pumped semiconductor laser

The influence of the external and internal resonator parameters on the laser emission spectral and spatial characteristics has been investigated. Single longitudinal mode operation of the electron-beam-pumped visible semiconductor laser with an external resonator has been observed. A single-mode peak power of 0.8 W and beam divergence of less than 3° were achieved.     

无纵模匹配注入锁定短脉冲染料激光器

本文报道了没有纵模匹配的注入锁定短脉冲染料激光器.实验结果表明,该激光器系统具有波长连续可调谐,脉冲短,输出线宽窄,功率高等特点.     

Measurement of stimulated transverse mode mixing in a free electron laser

We report the first measurement of the off-diagonal terms in the transverse gain matrix in a free electron laser. We show that the higher order transverse modes stimulated in the FEL interaction diminish in amplitude as the electron beam size is increased, that the far field and the near field effects of the excited modes are not equivalent, and that in this low divergence case, the mode mixing is insensitive to the resonance parameter. Remarkably close agreement is demonstrated with the theory [1]. The effects of a multiple mode input beam are also observed, and the theoretical expression is derived.     

Highly reliable 200 mW AlGaAs laser diode with fundamental transverse mode

A highly reliable 200 mW AlGaAs laser diode with a fundamental transverse mode has been developed, by optimising its structure with a 0.8 mu m thick p-cladding layer, a 1200 mu m long cavity length, and a front facet coating with a low reflectivity of 2%. The maximum output power was 500 mW, and stable fundamental transverse mode operation was obtained up to 350 mW. Stable operation under 200 mW and 50 degrees C was confirmed for more than 1200 h. Optical feedback noise was below 3*10/sup -14/ Hz/sup -1/.<>     

A pulse transmission mode Q-switched Nd:YLF laser pumped bycylindrical microlens-collimated diode bars

A Q-switched cavity-dumped single-transverse-mode Nd:YLF laser pumped by two 60-W quasi-CW diode bars collimated using cylindrical microlens technology produced 4-mJ, 4.5-ns pulses. The pump geometry employed has many of the advantages of longitudinal pumping yet allows the use of high-power quasi-CW bars while requiring only 1 optical element     

Fundamental transverse and longitudinal mode oscillation in terraced substrate GaAs-(GaAl)As lasers

A new, simple structure for a stripe-geometry laser is proposed. A double heterostructure is fabricated on a terraced substrate, providing a modified rib-waveguide structure in the active layer. A lasing mode is confined and stabilized in the narrow area between two adjacent bends of the active layer. The terraced substrate laser exhibits a stable, single longitudinal mode oscillation as well as a fundamental transverse mode oscillation in CW operation. No kinks have been observed in light-output versus current characteristics. The linearity continues up to ten times the threshold in the pulsed operation at which the power output is 150 mW per facet.     

Stable and widely tunable wavelength-spacing single longitudinal mode dual-wavelength erbium-doped fiber laser

In this paper, a novel and simple widely tunable wavelength-spacing single longitudinal mode (SLM) dual-wavelength erbium-doped fiber laser (EDFL) based on the tunable filter group, a passive feedback fiber ring (FFR) and saturable absorber (SA), is proposed and demonstrated experimentally. Experiment results show that the wavelength spacing can tune from 0.8 nm up to 17 nm, which has potential to generate terahertz (THz) waves by photo-mixing the lasing wavelengths in a high-speed photo-detector, and the maximum fluctuation of peak power of EDFL is less than 0.37 dB within 75 min and the optical signal-to-noise ratio is more than 30 dB at room temperature. In the absence of high-speed photo-detector, THz beat-note is also successively observed with the help of an autocorrelator. Moreover, dual-wavelength fiber laser can selectively realize one wavelength lasing by simply tuning filters.