“…In the past decade, many applications of the sol−gel process to the preparation of thin film, fiber, and monolithic optical materials have been reported. − The potential advantages of the sol−gel method for preparing optical materials include obtaining new chemical compositions, better purity, and more convenient processing conditions. Optical properties achieved in sol−gel materials include 1,2 graded refractive indexes, waveguiding, chemical sensing, optical amplification, frequency doubling, and lasing.…”