Optical Science and Engineering ETDs


Seth Melgaard

Publication Date



This dissertation compiles recent achievements in optical refrigeration, cooling a 10% wt. Ytterbium doped Yttrium Lithium Fluoride (Yb+3:YLF) crystal via anti-Stokes fluorescence to a record low temperature ~114(+\\-1)K (below NIST-defined cryogenic 123 K) from room temperature (ΔT ~185 K) in a single stage with a cooling power of 190mW. The demonstration of the coldest temperature to date, without the use of liquid cryogens or mechanical refrigerators, is achieved by taking advantage of the Stark manifold resonance and high doping concentration available in a crystalline host, outperforming multi-stage Peltier coolers. A novel technique probing local temperature changes experimentally verifies the cooling efficiency model with expected cooling to 93 K with the current crystal. With modest improvements to parasitic background absorption through the reduction of identified impurities, theory predicts cooling that approaches liquid nitrogen temperatures at 77 K. With this accomplishment, implementation of all solid-state cryo-cooling has begun.

Degree Name

Optical Science and Engineering

Level of Degree


Department Name

Optical Science and Engineering

First Advisor

Sheik-Bahae, Mansoor

First Committee Member (Chair)

Lester, Luke

Second Committee Member

Hehlen, Markus

Third Committee Member

Malloy, Kevin


Air Force Office of Scientific Research, Defense Advanced Research Projects Agency

Document Type