Lithium niobate fibers

Hashimoto T., Kamiya K., Nasu H. Strengthening of sol-gel-derived Si02 glass fibers by incorporating colloidal silica particles. J. Non-Cryst. Solids 1992 143 31-39 Hirano S., Hayashi T., Nosaki K., Kato K. Preparation of stoichiometric Cryst. lithium niobate fibers by sol-gel processing with metal alkoxides. J. Am. Ceram. Soc. 1989 72 707-709 Horikiri S., Tsuji K., Abe Y., Fukiu A., Ichiki E. US Patent 4,101,615 (1978)... 

Lithium Niobate. Lithium niobate [12031 -64-9], LiNbO, is normally formed by reaction of lithium hydroxide and niobium oxide. The salt has important uses in switches for optical fiber communication systems and is the material of choice in many electrooptic appHcations including waveguide modulators and sound acoustic wave devices. Crystals of lithium niobate ate usually grown by the Czochralski method foUowed by infiltration of wafers by metal vapor to adjust the index of refraction. 

Liquid crystal, thermochromic material Fiber itself Lithium niobate Gallium arsenide, various phosphors... 

M.A. Arbore et al.. Frequency doubling of femtosecond erbium fiber soliton lasers in periodically poled lithium niobate. Opt. Lett. 22, 13 (1997)... 

M. Matsukura, Z. Chen, M. Adachi and A. Kawabata, Growth of potassium lithium niobate single-crystal fibers by the laser-heated pedestal growth method, Jpn. J. Appl. Phys., 36, Part 1, No. 9B. 5947-5949 (1997). 

W. Que and S. Lim, Evaluation of micro-structure characteristics of lithium niobate single-crystal fiber with... 

Lithium niobate [niobium + -ate[ (1966) n. LiNb03. A crystaUine material whose physical properties change in response to pressure or the presence of an electric field and which is used in fiber optics and as a synthetic gemstone. 

Adding all of these losses together results in fiber-to-fiber losses of commercial devices for the Mach-Zehnder configuration of 3-5 dB in lithium niobate and 10-12 dB in GaAs. 

In virtually aU cases the modulator has two fiber attachments, instead of the one the diode laser required. The fiber coupling loss in lithium niobate is low because the waveguide mode is reasonably closely matched to the fiber mode. However, active alignment is still required, which today is done manually. Automated fiber attachment equipment is in development to eliminate this labor intensive, and hence costly, step. 

Lithium niobate modulators have been used for a number of years in high capacity fiber optic transmission systems. The combination of an external modulator and a CW laser produces a more noise-free signal than a diode laser modulated by current drive. In spite of this advantage, large-scale use of modulators was not realized until recently because of earlier stability problems (Ko-rotky and Veselka, 1996). 

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