Batop SAM 可饱和吸收体

内容：

微芯片安装

工作原理

脉冲能量Ep

重复率frep

脉冲宽度tp

微芯片安装

上图所示是的被动调Q的单片微片激光器由Nd掺杂YVO4激光晶体和可饱和吸收镜(SAM)粘合在一起组成。激光腔体长度L在区域100μm..300μm主要由激光晶体厚度决定。典型掺Nd是2&或3%。 来自一个连续二极管激光的线性极化808nm泵浦光平行面向c轴自动对焦激光晶体。激光晶体中的一个典型的泵浦光斑直径约为50μm-100μm。1064nm波长单模激光输出光脉冲是从分色镜中反射出。

微芯片的主要特性取决于以下参数：

脉冲能量Ep

重复率frep

脉冲宽度tp

工作原理

可饱和吸收体（SAM）作为被动调Q开关。 对波长为1064nm的激光来说低强度非饱和SAM反射率在0.75-0.9的区域。激光晶体的连续泵浦上部将被填补直到获得足够大的自发辐射。然后SAM饱和，激光器发出一个强大的短脉冲。 在连续泵浦期间，发展重复，重复频率德国财务报告管理小组inceasing与泵浦功率密度接近线性关系。由于光能量的一部分是在SAM的吸收层消退，安排必须删除此芯片产生的热量。如果激光腔长度短，单模激光泵浦光斑直径小。

pulse energy E_p

_{According to the well established formalism (Journal of the Optical Society of America B， Vol. 16， Issue 3， pp. 376-388， 1999) of passive Q-switched microchip laser the pulse energy Ep can be estimated as follows:}

with

F_{sat，L saturation fluence of the laser material}

_{Apump spot area in the resonator}

_{ΔRmodulation depth of the SAM}

_{T transmission of the output coupler}

_{Ansnon-saturable losses， mainly from SAM}

_{With typical values Fsat，L = 37.3 mJ/cm2， A = 1.3x10-5cm2 ( 40 μm spot diameter)， ΔR = 0.1， T = 0.1， and loss = 0.05 the pulse energy can be estimated to Ep ~ 32 nJ.}

_{repetition rate frep}

The average output power P_av is proportional to the pump power. Therefore the repetition rate shows a linear behavior by changing the pump power according to:

with

_{ηs slope efficiency}

_{Pp pump power}

_{PP，th pump power threshold}

By changing the pump power P_P repetition rates between 100 kHz and 2 MHz can be realized with a nearly constant pulse energy E_P. Because the pulses start with spontaneous emission， the repetition rate shows a time jitter of about 1 %， increasing with decreasing pump power and rate.

pulse duration t_P

The pulse duration t_P in passive Q-switched lasers can be estimated by:

with

TR resonator round trip time

ΔR modulation depth of the SAM

n refractive index of the resonator material

L resonator length

c speed of light in vacuum.

With a short laser crystal length L = 0.2 mm， refractive index n ~ 1.95， and a SAM modulation depth of ΔR = 0.1 the pulse duration is about 91 ps.