High Power Laser Science and Engineering, (2019), Vol. 7, e44, 9 pages.
© The Author(s) 2019. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/
licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
doi:10.1017/hpl.2019.28
Simulation and analysis of the time evolution of laser
power and temperature in static pulsed XPALs
Chenyi Su , Binglin Shen , Xingqi Xu , Chunsheng Xia , and Bailiang Pan
Department of Physics, Zhejiang University, Hangzhou 310027, China
(Received 12 January 2019; revised 22 April 2019; accepted 4 June 2019)
Abstract
A theoretical model is established to describe the thermal dynamics and laser kinetics in a static pulsed exciplex pumped
Cs–Ar laser (XPAL). The temporal behaviors of both the laser output power and temperature rise in XPALs with a long-
time pulse and multi-pulse operation modes are calculated and analyzed. In the case of long-time pulse pumping, the
results show that the initial laser power increases with a rise in the initial operating temperature, but the laser power
decreases quickly due to heat accumulation. In the case of multi-pulse operation, simulation results show that the optimal
laser output power can be obtained by appropriately increasing the initial temperature and reducing the thermal relaxation
time.
Keywords: excimer lasers; simulation; theoretical model
1. Introduction
An optically pumped atomic Rb vapor laser operating on the
resonance at 795 nm, the diode-pumped alkali vapor laser
(DPAL), was first realized by Krupke et al. in 2003
[1]
. It has
many advantages, such as good beam quality with high laser
power, higher energy conversion efficiency, and a reduced
thermal effect. However, researchers noticed that an un-
avoidable drawback in DPAL hindered its development. The
narrow linewidth of alkali atomic absorption (∼0.02 nm)
means only few commercial semiconductor lasers can be
chosen as effective pump sources for DPAL systems due
to the spectrally resolved width of commercial laser diodes
being on the order of magnitude of 1 nm
[2]
. To address
this issue, adding high-pressure helium, 19,000–38,000 Torr
(1 Torr = 133.32 Pa), to broaden the linewidth was proposed
by Krupke et al.
[3]
.
In another approach, the exciplex pumped alkali laser
(XPAL) system using heavier rare gases as collision partners
to broaden the absorption spectrum
[4]
was proposed by
Readle et al. in 2008
[5]
, which made use of optical pumping
of Cs–Ar atomic collision pairs. In addition, two operating
mechanisms for XPALs have also been demonstrated as four-
level and five-level systems
[6–10]
. As a new type of laser,
XPAL has attracted much attention and been under intensive
development for the past decade. Palla and Carroll have
conducted valuable theoretical studies on the dynamics of
Correspondence to: B. Pan, Department of Physics, Zhejiang University,
Hangzhou 310027, China. Email: pbl66@zju.edu.cn
Figure 1. Schematic diagram of the XPAL configuration.
atomic binding and separation
[11]
, and proved a BLAZE-V
model for describing mathematical calculations on the XPAL
system. In their model, the theoretical performance of XPAL
under CW operation has been predicted and analyzed
[12]
.
Pan’s team carried out research on the significance of thermal
effects on an operating XPAL system. The results showed
that due to the high heat loading generated by multiple
transitions, a sharp temperature gradient occurs in the cell,
which may cause the experimental device to melt down
and the stimulated emission to quench. Therefore, they
introduced gas flow into the system to reduce the temperature
gradient
[13]
and applied fluid methods to the CW XPAL
system, with good simulation results being achieved
[14]
. In
1