The Application of Cryogenic Laser Physics to the Development of High Average Power Ultra-Short Pulse Lasers

Abstract

Ultrafast laser physics continues to advance at a rapid pace, driven primarily by the development of more powerful and sophisticated diode-pumping sources, the development of new laser materials, and new laser and amplification approaches such as optical parametric chirped-pulse amplification. The rapid development of high average power cryogenic laser sources seems likely to play a crucial role in realizing the long-sought goal of powerful ultrafast sources that offer concomitant high peak and average powers. In this paper, we review the optical, thermal, thermo-optic and laser parameters important to cryogenic laser technology, recently achieved laser and laser materials progress, the progression of cryogenic laser technology, discuss the importance of cryogenic laser technology in ultrafast laser science, and what advances are likely to be achieved in the near-future.

Cryogenic nanosecond and picosecond high average and peak power (HAPP) pump lasers for ultrafast applications

“…Previous publications also provide a wealth of information [1][2][3][15][16][17][18][19][20][21][22] . It is now well known that the value of the thermal conductivity increases as temperature is lowered, for all measured single crystals as well as for their ceramic counterparts.…”

“…We have recently provided a detailed comprehensive review of the important thermal, thermo-optic, elastic, laser, optical, nonlinear and dispersion effects for a number of laser materials [3] , and will not repeat that discussion here. Previous publications also provide a wealth of information [1][2][3][15][16][17][18][19][20][21][22] .…”

“…Figure of merit Γ T addresses changes in the index of refraction due to temperature gradients, and Γ S applies to changes in the index due to stress (or strain) effects. For a detailed discussion of Equations (1) and (2) please consult [3] .…”

“…For the case where a major design goal is to eliminate or reduce aberrations to residual levels, we can define two figures of merit Γ as follows [3] : YLF thermal conductivity along a-axis (blue diamonds) and c-axis (green triangles), thermal expansion coefficient along a-axis (red squares) and c-axis (black diamonds), and (dn/dT ) along the a-axis (pink circles) and the c-axis (orange circles), all as a function of absolute temperature. Figure 5.…”

“…The progress made has been well documented in two landmark papers [1,2] , and more recently in a comprehensive review of the technology [3] , including its applicability to ultrafast lasers. In this paper, we discuss cryogenic nanosecond and picosecond lasers, the former having the potential to substantially increase the performance of traditional Ti:Al 2 O 3 lasers, and the latter to provide powerful pump sources for optical parametric chirped pulse amplification (OPCPA) systems.…”