激光原理第四章ppt課件(已修改)
2025-05-13 08:44 本頁(yè)面
【正文】 深圳大學(xué)電子科學(xué)與技術(shù)學(xué)院 三 輸出功率與能量 ? In section we derived an expression for the threshold population inversion at which the laser gain bees equal to the losses. We would expect that as the pumping intensity is increased beyond the point at which N2N1=Nt the laser will break into oscillation and emit power. In this section we obtain the expression relating the laser power output to the pumping intensity. We also treat the problem of optimum couplingthat is, of the mirror transmission that results in the maximum power output. 深圳大學(xué)電子科學(xué)與技術(shù)學(xué)院 ? 激光器穩(wěn)態(tài)工作的建立 ? 連續(xù)或長(zhǎng)脈沖激光器的輸出功率(output power) ? 短脈沖激光器的輸出能量 (output energy) 深圳大學(xué)電子科學(xué)與技術(shù)學(xué)院 ? In chapter 3 we found that an atomic medium with an inverted population (N2N1) is capable of amplifying an electromagic wave if the latter’s frequency falls within the transition lineshape. Consider next the case in which the laser medium is placed inside an optical resonator. 深圳大學(xué)電子科學(xué)與技術(shù)學(xué)院 ? As the electromagic wave bounces back and forth between the two reflectors it passed trough the laser medium and is amplified. If the amplification exceeds the losses caused by imperfect reflection in the mirrors and scattering in the laser medium, the energy stored in the resonator will increase with time. This causes the amplification constant to decrease as a result of gain saturation. 深圳大學(xué)電子科學(xué)與技術(shù)學(xué)院 ? The oscillation level will keep increasing until the saturated gain per pass just equals the losses. A
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