Whispering gallery mode (WGM) lasers are well-known for their small sizes, low thresholds and narrow linewidths, and have been the subject of research and development for more than two decades. However most of the initial reports and studies have focused on near-IR and visible WGM microlasers. Recent advances in the synthesis, doping and processing of high quality mid-IR transparent glasses have provided the means to extend the wavelengths of these microlasers to the mid-IR range. In this paper, we present a detailed characterization of a compact and low-cost mid-IR spherical WGM microlaser based on heavily doped Er:ZBLAN glass operating near 2.7 µm with an estimated linewidth less than 1 MHz. We describe experimental results on observed single-mode and multimode spectra, thermal tuning, and polarization characteristics of such microlasers. Using a simple analysis of spherical microresonator modes and including considerations of pump and laser mode overlap we provide guidelines for optimized microlaser design.
We describe the design of a new family of high spectral brightness narrow linewidth (NLW) mid-infrared (MIR) lasers --of < 1 MHz anticipated linewidths --with potential for operation at any target wavelength between 2.5 and 9.5 µm. More specifically, we analyze the potential performance characteristics of mid-infrared distributed feedback (DFB) Raman fiber lasers (RFLs) based on π-phase-shifted (PPS) Fiber Bragg Gratings (FBGs) written in appropriately chosen low-phononenergy glass fibers. In particular, we calculate anticipated threshold pump powers for optimal laser designs and pump wavelengths for single frequency (fundamental mode) operation of specific mid-infrared DFB-RFLs operating at chosen target wavelengths, and show that these pump powers can be as low as a few milliWatts for MIR DFB-RFLs fabricated with appropriate low-loss small mode area single mode fibers. As such, we clearly establish the PPS-DFB RFL platform as a very practical approach for constructing a broad range of narrow linewidth MIR coherent sources for numerous applications, including proximal and remote sensing of molecules and various high spectral brightness and long coherence length MIR applications.
We discuss issues re: power scaling of mid-IR Er:ZBLAN spherical microlasers and demonstrate achievement of near-milliwatt power levels from a narrow-linewidth (Δλ < 50 pm) 2.71 µm laser source based on an Er:ZBLAN microlaser.Narrow linewidth mid-infrared (MIR) lasers are important sources for trace level detection of a broad range of molecular species by spectroscopic methods [1,2]. For this application, interband and quantum cascade semiconductor lasers (ICLs and QCLs) --of distributed feedback (DFB) design [3,4] --are currently the most readily available compact sources of narrow-linewidth mid-IR emission (Δν < 30 MHz). However, the complexity of the growth and fabrication process of these semiconductor lasers makes them relatively expensive, particularly when different designs are needed in small quantities. Moreover, since the circulating optical power is not easily accessible in ICLs and QCLs, these lasers are not easily adaptable for ultrahigh-sensitivity intracavity molecular detection. In addition, the 2.7 -2.8 µm MIR spectral range for high-sensitivity molecular detection application of several important molecular species (such as H 2 O, CO 2 , HF, HOCL) is not easily achievable by narrow linewidth ICLs or QCLs [3,4].Glass-based whispering gallery mode lasers (WGMLs) are alternative compact sources of narrow linewidth NIR [5,6] and MIR radiation [7,8,9] that are not only highly amenable for intracavity sensing applications (because of the extension of the evanescent tail into the surrounding analyte-bearing medium), but also readily lend themselves to much simpler fabrication processes [5-10], largely because high quality factor ("high-Q") glass WGML microspheres of variable dimensions are relatively easy to fabricate individually, and the doped-glass gain medium also serves as the laser cavity without the need for any external mirror or feedback
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.