High-power surface emitting semiconductor laser with extended vertical compound cavity

Novel, electrically pumped, vertical compound cavity InGaAs lasers emitting at 980 nm are described. These have generated 1 W continuous-wave multimode and 0.5 W continuous-wave in a fundamental TEM/sub 00/ mode and single frequency, with 90% coupling efficiency into a singlemode fibre.     

Dynamics of a two-mode semiconductor laser

The authors analyze the properties of a semiconductor laser in a ring cavity when two modes can oscillate. With this model it is shown that phase-sensitive mode-mode interactions can influence the laser dynamics through their dependence on the spatial Fourier components of the carrier density. In particular, these interactions provide a mechanism by which single-mode solutions are destabilized while periodic and quasi-periodic two-mode solutions can occur     

Feedback phenomena in a semiconductor laser induced by distantreflectors

Multiple pass resonances in the noise spectrum and low-frequency self-oscillations in asymmetric geometrical configurations are described. The double peaked structure of the external cavity resonance f_c (at c/2L), the `subharmonic cascading' from f_c, and the generation of subharmonics of a modulated injection current are detailed. The exact field intensity distribution in the passive external resonator is shown to command these phenomena which reveal intermingled spatial and dynamical effects. The different behaviors are related to the characteristic curves of the laser. The authors have found that when the external cavity laser operates in its unstable regime, a locking of the otherwise randomly distributed intensity drops can occur giving a narrow resonance in the noise spectrum. In addition, based on the authors' observations, adapted rate equations are built starting from the Lang and Kobayashi model. Results show an adequate match between theory and experiments for the detailed microwave spectra, multiple pass resonances of the external cavity, and low-frequency resonances     

双波长可调外腔半导体激光器

提出了一种基于体布拉格光栅（VBG）和横向啁啾体布拉格光栅（TCVBG）组合的双光栅外腔半导体激光器,该外腔半导体激光器采用反射率15%的体光栅和反射率17%的啁啾体布拉格光栅作为反馈元件和模式选择元件,实现特定波长的选择和调谐,实验研究了外腔激光器的功率-电流特性、光谱特性和波长调谐特性。实验结果表明:双光栅外腔半导体激光器最大输出功率为1.96 W,斜率效率为0.94 W/A,外腔效率达到78%。输出光谱为双波长,一个波长为808.6 nm,另一个波长连续可调,通过改变横向啁啾体光栅的位置,该波长可从800 nm调谐至815 nm,可调范围达15 nm,在整个可调范围内两个波长的谱线宽度（FWHM）均小于0.3 nm。     

Continuously tuned external cavity semiconductor laser

Continuous tuning (no mode hops) of a grating-tuned external-cavity semiconductor laser by rotation of the grating about a carefully selected point is analyzed and demonstrated using a laser containing a prism beam expander. The analysis predicts the continuous tuning range as a function of pivot-point position and is used to select the point for maximum continuous tuning range. Because dispersive optical elements in the cavity were found to limit the continuous tuning range, the model was modified to include dispersion to first order. The dispersion correction improved the maximum observed tuning range of the 1300-nm-wavelength laser from 600 GHz to nearly 3000 GHz. Details of the cavity and mechanical design as well as pivot-point tolerances are also included     

Stability analysis for a semiconductor laser in an external cavity

A detailed theoretical analysis of stability is presented for a semiconductor laser in an external cavity. The limits of stable operation are determined as a function of the external cavity parameters and the linewidth enhancement factor α. Instability is related to jumps of the laser frequency between external cavity modes (frequency bistability) or to feedback-induced intensity pulsations due to the carrier density dependence of the refractive index. The limit of bistability is derived from the steady-state solutions of the rate equations and the intensity pulsation limit is obtained from a small-signal analysis. This analysis also gives the location of zeros in the system determinant and the resulting FM noise spectrum. For practical applications we emphasize the determination of the stable tuning range for the phase in the external cavity and the classification of the possible types of instability for various feedback levels.     

Vertical cavity surface-emitting semiconductor laser with CWinjection laser pumping

Room-temperature CW operation of a GaAs/AlGaAs vertical cavity surface-emitting laser with a resonant periodic gain medium, using a GaAs/AlGaAs diode laser array as a pump source, is discussed. Pumping thresholds as low as 11 mW at 730 nm, output powers as high as 10 mW at 856 nm, and external quantum efficiencies as high as 70% are obtained, with considerably improved temporal and spatial coherence properties compared to the pump laser. This is the first reported operation of such a laser with an efficient, compact pump source, demonstrating its suitability for efficient integration     

梯形衬底大光腔可见光AlGaAs半导体激光器

采用液相外延技术,试制了梯形衬底大光腔(LOC)可见光AlGaAs半导体激光器。其波长为717.2～770.0nm,室温(298K)连续工作阈值电流为300mA,在1.5倍阈值时可实现单纵模、基横模工作。本文给出了器件的一些电学和光学特性.     

Dynamics of a multimode semiconductor laser with optical feedback

A new model of a multi-longitudinal-mode semiconductor laser with weak optical feedback is proposed. This model generalizes the well-known Tang-Statz-deMars equations, which are derived from the first principles and adequately describe solid-state lasers to a semiconductor active medium. Steady states of the model and the spectrum of relaxation oscillations are found, and the laser dynamics in the chaotic regime of low-frequency fluctuations of intensity is investigated. It is established that the dynamic properties of the proposed model depend mainly on the carrier diffusion, which controls mode-mode coupling in the active medium via spread of gratings of spatial inversion. The results obtained are compared with the predictions of previous semiphenomenological models and the scope of applicability of these models is determined.

     

光电流稳频复合腔调谐CO_2波导激光器的研究

研究了CO_2波导激光器光电流效应及光电流稳频、复合腔调频的CO_2波导激光器系统。获得60条谱线连续分立输出。单线最大输出功率为8W,长时间稳定度优于1％。     

复合腔可调谐CO_2波导激光器的研究

研究了用光栅复合腔调谐的CO_2波导激光器,在63条激光谱线上获得了激光输出,单支谱线最大功率为1W。分析了复合腔理论,理论与实验结果是一致的。     

自聚焦棒外腔单频半导体激光器

本文提出了用振幅耦合因子描述激光器谐振腔与自聚焦棒光波导结构的差异及耦合腔的衍射损耗;讨论了自聚焦棒相对激光器作微小偏移对振幅耦合因子的影响.对自聚焦棒外腔半导体激光器的选模理论进行了实验验证.实现了单纵模运转,其边模抑制比大于35dB,线宽小于21MHz,最大的波长调谐范围为11nm.     

外腔半导体激光器的线宽

本文用量子力学的方法求得了外腔半导体激光器(LD)的线宽,给出了抑制LD线宽的最佳反馈条件。     

外腔半导体激光器宽带调谐特性

本文分析了强反馈外腔半导体激光器的宽带频率调谐特性,得到了最大频率调谐范围公式,利用1.5μm外腔半导体激光器实现了1.45μm至1.57μm范围内的波长宽带调谐(120nm调谐范围)。     

Theory of active mode locking of a semiconductor laser in an external cavity

An analytical treatment is given for the active mode locking of a semiconductor laser in an external resonator. The width of the mode-locked pulses is obtained as a function of the laser and cavity parameters and the amount of frequency detuning. The effects of self-modulation and saturation are included in the treatment. The pulse output is compared with that obtained by a strong modulation of the laser diode with no external cavity.     

Hysteresis and multistable behaviour in a polarisation self-modulated external ring cavity semiconductor laser

The polarisation self-modulated laser exhibits various 'polarisation modes' which can be switched among themselves by varying the applied voltage of the intra-cavity electro-optic waveplate. Strong hysteresis tendencies are displayed in this switching behaviour and multistability has been observed. Switching among the modes can also be simply initiated by perturbing the diode laser with short current pulses.<>     

Voltage change across the self-coupled semiconductor laser

The results of experimental and theoretical analyses on the voltage changes across the GaAlAs semiconductor laser diodes caused by the onset of optical feedback are described. The dependence of voltage changes on the injection current and on the feedback ratio indicates that the origins of the voltage changes are the photoconduction effect and a reduction of the quasi-Fermi level related to the enhanced stimulated emission. The calculated voltage changes based on the theoretical analyses using the published laser parameters are in good agreement with the experimental ones. The preferable specifications for a laser diode (LD) to exhibit a larger voltage change at the onset of optical feedback are discussed.     

Spatially singlemode broad-area semiconductor laser with planar external cavity

A broad-area laser diode combined with a planar external waveguide cavity operates in the fundamental mode and reshapes the output emission into a circular 15/spl deg/ beam. A 500 /spl mu/m-long by 40 /spl mu/m-wide laser diode with uncoated facets coupled with the uncoated ModeReShaper (MRS) planar chip has a coupling efficiency of /spl sim/40% and stabilised the fundamental mode at drive currents up to three-times threshold.     

光泵浦外腔半导体激光器的研究进展

从谐振腔和半导体增益介质的角度介绍了光泵浦外腔面发射半导体激光器的基本结构,评述了国内外在该领域的最新研究进展,探讨了该类型激光器在大功率、小型化技术方面的发展前景。     

External cavity semiconductor laser comprising brewster-angled rectangular core fibre

A GaInAsP semiconductor laser diode, with one of its facets Brewster angled was coupled to a Brewster angled rectangular core fibre to obtain an external cavity. Very good coupling efficiency and a high degree of polarisation of the output beam has been obtained.<>