饱和吸收光谱探测系统
(Saturated Absorption Spectra Detecting System）

系统介绍 （System Introduction）

此系统是在外腔半导体激光器UQEL100基础上的探测饱和吸收光谱的解决方案。它由外腔半导体激光奇UQEL100、光隔离器、饱和吸收光路和低噪声光电探测器四个主要部分构成。它探测饱和吸收光谱的原理是：探测光和反抽运光相对射入样品室并在空间上路径重合，扫描激光器频率，当光频率和原子能级近共振时，反抽运光把路径上的原子抽运到激发态，使得探测光信号的多普勒本底上出现透射峰，探测碱金属原子的饱和吸收光谱时一般会出现六个透射峰，其中三个为共振线，三个为交叉线。此饱和吸收光谱探测系统可得到有多普勒本底的信号，也可以得到消多普勒本底的信号。根据用户的需要，系统可以做相应的调整。此系统适用于冷原子物理[1]、激光光谱[2]、激光稳频[3]、、量子信息、计量、环境监测、工业测量等方面。

主要指标(Specifications)：

适用波长（wavelength）	375, 400, 635, 655, 675, 685, 780, 790, 810, 850, 895, 935, 1060, 1260, 1310, 1380, 1450, 1550, 1630, 1700, .nm etc
可用输出功率（Output power on Line)	≥10mW
工作物质(Sampling Material)	Rb, Rb, Cs, Li, Ca, I2, CH4, CO
光隔离度(Optical isolation ratio)	≥50dB
光谱使用功率(Light Power for Spectra)	≤0.5mW
信噪比(Signal to Noise Ratio)	≥30dB
系统尺寸(System Size)	600mm x 360mm x 180mm
工作温度（Operating temperature）	15°C ~35°C

（Schematic diagram of Saturated Absorption Spectra Detecting System）

System Introduction

The system is a solution to saturated absorption spectra detecting, based on external cavity diode laser UQEL100. It consists of four main parts: external cavity diode laser UQEL100, optical isolator, light path for saturated absorption spectra and low noise photo detector. The system works as the following: The probing light and the re-pumping beam counter-propagate into the sampling cell, and overlap in space. While the frequency of diode laser is scanned to resonant on the transition frequency of the sampling material, the pumping light will pump the sampling material to the excited states and the probing light will pass the excited material with less absorption, which is detected by the photo detector showing transmission peaks on the Doppler absorption background. Generally, the spectra from alkali metals shows six transmission peaks, three of which are resonant lines and others are crossover lines. According to the demands of customers, spectra with or without Doppler background can be both obtained. The system can be utilized in such diverse applications as cold atom physics^[1], laser spectroscopy^[2], laser frequency stabilization^[3], quantum information, metrology, environmental monitor and industrial measurement etc.

Frequency beat signal of two UQEL100 lasers	Saturated absorption spectrum of 87Rb

[1] Lin Xia, Xu Xu, Rui Guo, Fan Yang, Wei Xiong, Juntao Li, Qianli Ma, Xiaoji Zhou, Hong Guo, and Xuzong Chen, Phys. Rev. A 77, 043622 (2008)
[2] Yimin Li, Xuzong Chen, Jianhua Gan, Wangxi Ji, Jingshan Hua, Donghai Yang, Yiqiu Wang，Chin.Phys.Lett., Vol.13,No.6,424(1996)
[3] X.Z. Chen, K. Zhang, J. Zang, Y. Akimoto, T. Kasahara, K. Sakamoto, H. Inaba, Proceedings of SPIE, Vol 3547, 194-202 (1998)