Sol–Gel-Derived Spheres for Spherical Microcavity

Abstract

Encapsulation of light to small spheres ensures the highest quality factor ( Q factor) to enhance the interaction between light and materials. In this Account, we describe the fabrication of micrometer-sized spherical particles of organic-inorganic hybrid materials to study the potential ability as a spherical cavity laser. The spherical particles prepared by the vibrating orifice technique included those of nondoped and doped with organic dyes and rare-earth-metal ions, and some of them were cladded with low-index-coating hybrid materials. Coating of the spheres was carried out by aiming at practical applications: high refractive index spheres from n D = 1.72 to 2.5 prepared by the technique and glass spheres of n D = 1.93. They were pumped by second harmonic pulses of a Q-switched Nd:YAG laser (532 nm wavelength) and CW Ar (+) laser (514 nm wavelength) to investigate as spherical cavity microlasers. The emission from spheres originated from the photoluminescence of dopants and Raman scattering of matrix materials. Lasing or resonant light emission from these spheres were performed by the direct-laser-light-pumping and the light-coupling techniques using an optical waveguide coupler.

Spherical Cavity Glass Lasers for Multiwavelength Emission

“… Thresholds of laser emission in various small‐sized resonators: fiber lasers (R) 3,4 ; waveguide lasers (Nd 3+ ) 6 ; glass sphere lasers pumped by direct pumping, 19 half‐polished fiber coupler (R and Nd 3+ ), 17 terrace (R), 8,23 and taper fibers (R). 15 (R) and (Nd 3+ ) represent stimulated Raman emission and laser emission due to Nd 3+ .…”

“…Spherical resonators have potential uses, such as a multiwavelength laser, a low threshold laser, and optical signal processors. A brief history of spherical cavity lasers has been summarized in our previous report 8 . The first trial of laser action in spherical resonator was reported in Sm 2+ ‐doped CaF 2 spheres of millimeter size in 1961 9 .…”

“…A brief history of spherical cavity lasers has been summarized in our previous report. 8 The first trial of laser action in spherical resonator was reported in Sm 21 -doped CaF 2 spheres of millimeter size in 1961. 9 Early works have already shown the ability of spherical resonators through Raman excitation in microdroplets of 60 mm in diameter.…”

Enhancement of stimulated Raman scattering in terrace-microspheres

“…In our previous work, a micrometer-sized spherical cavity laser having a terrace-shaped pumping light entrance was investigated [10][11][12]. A terrace portion was formed on microspheres of multicomponent glasses (n D ¼ 1:93) several tens of micrometers in diameter using organic-inorganic hybrid materials (n D ¼ 1:45) in the binary system of 3-methacryloxypropyltrimethoxysilane (MOPS) and tetramethoxysilane (TMOS).…”

Enhancement of stimulated Raman scattering in Nd3+-doped terrace-microspheres

“…Therefore efficient coupling technique to the multicomponent glass spheres is required for practical devices. In our previous works, micrometer-size spherical cavity laser having a terrace-shaped pumping light entrance was investigated [10][11][12]. Terrace portion was formed on the microspheres of multi-component glasses (n D =1.93) of several tens of micrometers in diameter by using organicinorganic hybrid materials (n D =1.45) in the binary system of 3-methacryloxypropyltrimethoxysilane (MOPS) and tetramethoxysilane (TMOS).…”