Research on Control of Spontaneous Emission in a Laser with Very Short Cavity

1理论（1）超短光腔的成对介质板模型分析：该模型给出了法布里-珀罗型超短光腔特性的解析表达式。利用这个模型，自发辐射率到辐射模式。它们耦合到外部空间，并且进入引导模式。其沿着电介质板行进。的驻波模式分析的基础上计算。的角分布的发射和耦合比到一个特定的腔模式（准模）进行评估。(2)分析现实的非常短的腔：类似的分析进行了一个腔有一对镜子与多介质层使用矩阵方法。对于导模的计算，估计并使用模的有效密度。(3)有效面积概念的提出：适用于法布里-珀罗型超短光腔。计算结果表明，该谐振腔谐振模的空间场分布 ...更多信息 由反射镜反射率和腔长决定。提出了与场分布有关的有效面积的概念。（4）非微扰分析：本文对真空拉比振荡进行了非微扰分析，提出了有效拉比场的概念。2.实验用波长为520 nm，脉宽为1 ns的激光脉冲激发，在长2-10 μ m的罗丹明6 G-乙醇溶液光腔中，与比色皿中相同染料溶液的荧光进行比较。短腔和比色皿的发射峰均在570 nm处。发射光谱宽度由34 nm减小到7.2nm，脉冲宽度由6.3ns减小到0.92ns。输出功率与输入功率的对数-对数图显示在测量范围内的斜率为2，该范围可能对应于从荧光到激光的瞬态。最小输入能量为0.5 μ J。需要进一步研究提高功率测量的灵敏度。少

1 Theory(1) Analysis of the paired-dielectic-slab-model of a very short optical cavity : This model allows for analytical expressions for the properties of a Fabry-Perot type very short optical cavity. Using this model, the spontaneous emission rate into radiative modes. which are coupled to the outer space, and that into guided modes. which travel along the dielectric slabs. are calculated on the basis of standing wave mode analysis. The angular distribution of the emission and the coupling ratio to a particular cavity mode (quasimode) are evaluated.(2) Analysis of realistic very short cavities : Similar analysis is performed for a cavity having a pair of mirrors with multi-dielectric layers using the matrix method. For calculation on the guided modes, effective density of modes are estimated and used.(3) Proposal of the concept of the effective area : For a Fabry-Perot type very short optical cavity. it is shown that the spatial fiel d distribution of the cavity resonant mode is dete … More rmined by the mirror reflectivities and the cavity length. The concept of effective area, related to the field distribution, is proposed'(4) Nonperturbative analysis : Nonperturbative analysis is made on "vacuum Rabi oscillation- and the concept of effective Rabi field is proposed.2 ExperimentOutput properties of a 2-10 mu m long optical cavities filled with Rhodamine 6G-ethanol solution, excited by a laser pulse of wavelength 520nm and of pulse duration lns, are compared with the fluorescence from the same dye solution in a cuvette. The emission peak was at 570 nm for both short cavity and cuvette. The emission spectal width decreased to 7.2na from 34nn and the pulse width was 0.92ns as compared with 6.3ns for the fluorescence. The output power versus input power in a log-log plot shows a slope of 2 over the mesured range, which range corresponds, probably, to the transient from fluorescence to lasing. The minimum input energy was 0.5 mu J. Improvement in sensitivity of power measurement is needed for further study. Less