Optical Science and Engineering ETDs

Publication Date

Spring 4-15-2020


This dissertation reports recent advances in mid-infrared (mid-IR) optical refrigeration and Radiation Balanced Lasers (RBLs). The first demonstration of optical refrigeration in Ho:YLF and Tm:YLF crystals as promising mid-IR laser cooling candidates is reported. Room temperature laser cooling efficiency of Tm- and Ho-doped crystals at different excitation polarization is measured and their external quantum efficiency and background absorption are extracted. Complete characterization of laser cooling samples is obtained via performing detailed low-temperature spectroscopic analysis, and their minimum achievable temperature as well as conditions to achieve laser cooling efficiency enhancement in mid-IR are investigated. By developing a Thulium-doped fiber amplifier, seeded with a Continuous Wave Optical Parametric Oscillator, power cooling experiments on Tm-doped crystals are performed. Finally, different approaches towards realizing mid-IR RBLs in Tm- and Ho-doped crystals are discussed, and optimized operation of such RBLs with conditions to achieve kW-level output intensities are modeled.

Degree Name

Optical Science and Engineering

Level of Degree


Department Name

Optical Science and Engineering

First Committee Member (Chair)

Mansoor Sheik-Bahae

Second Committee Member

Markus P Hehlen

Third Committee Member

Arash Mafi

Fourth Committee Member

Ganesh Balakrishnan


optical refrigeration, radiation balanced lasers, mid-IR optical parametric oscillator, Thulium, Holmium, Tm fiber amplifier

Document Type