Scaleable LED-pumped Room-temperature Maser using a Multi-blade Optical Injector

TL;DR

This paper introduces a novel multi-blade optical injector for room-temperature masers, enhancing pump efficiency and scalability, demonstrated through simulation, fabrication, and experimental validation with a pentacene:para-terphenyl gain medium.

Contribution

It presents a new multi-blade optical injector design that improves pumping uniformity and scalability for room-temperature masers, validated through interdisciplinary methods.

Findings

Multi-blade injector achieves more complete and uniform pumping.

Experimental maser oscillator successfully demonstrated with the new injector.

Analysis shows improved scalability over previous injection strategies.

Abstract

Though the performance of room-temperature masers has improved over the last decade, relatively little attention has been paid to the optics used to pump the maser's gain medium. In this work, we investigate a novel multi-blade optical ``injector'' that permits more effective and more scaleable pumping. The reported work encompasses an interdisciplinary mix of conceptualization, simulation, crystal growth, fabrication, and microwave engineering. Our gain medium is pentacene dissolved as a solid solution with para-terphenyl (Pc:PTP) molecular crystal. We accurately determine this pentacene's molecular absorption cross-section as a function of wavelength. Ray-tracing is then used to assess how different designs of waveguide inject light into the Pc:PTP crystal. A multi-blade injector made of high-refractive-index glass (namely Ohara S-TIH6) is predicted to pump it more completely and uniformly than previous designs. Upon hand-fabricating such an injector and Bridgman-growing a crystal of 0.1% Pc:PTP over it, an experimental maser oscillator using this combined injector-crystal assembly is demonstrated. The performance and scaleability of multiblade injection vis-a-vis alternative strategies is analyzed.