Optimization of 1.5 µm-Band LiNbO3 Quasiphase Matched Wavelength Converters for Optical Communication Systems

Chang-Qing XU  Ken FUJITA  Andrew R. PRATT  Yoh OGAWA  Takeshi KAMIJOH  

IEICE TRANSACTIONS on Electronics   Vol.E83-C   No.6   pp.884-891
Publication Date: 2000/06/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Advanced Optical Devices for Next Generation High-Speed Communication Systems and Photonic Networks)
Category: WDM Network Devices
wavelength converters,  LiNbO3 ,  quasiphase match,  waveguide,  WDM systems,  

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1.5 µm-band LiNbO3 quasiphase matched (QPM) wavelength converters consisting of a periodical domain inverted structure and a proton exchanged waveguide, have been studied in detail both theoretically and experimentally. Optimum device fabrication conditions are investigated with respected to waveguide propagation loss, coupling loss to a single-mode fiber and wavelength conversion efficiency. A normalized conversion efficiency as high as 200 %/W (by a SHG measurement) and a fiber-to-fiber insertion loss of less than 3.5 dB (@1.55 µm) is obtained for a wavelength converter module with a device length of 40 mm. It is shown that a highly uniform periodical domain inverted structure and a uniform proton exchange waveguide are key to obtaining efficient wavelength conversion. The tolerance of the waveguide width fluctuation is found to be very critical and is less than 20 nm for a 40 mm-long device. Future optimization of LiNbO3 QPM wavelength converters and the possible device applications in future optical communication systems are also presented.