Technological implementation of Bragg grating reflectors in Ti:LiNbO3 waveguides by proton exchange

Abstract

The authors propose and demonstrate a simple and novel method for fabrication of efficient Bragg grating reflectors at telecommunication wavelengths in titanium-indiffused lithium niobate single-mode channel waveguides. This technique is based on the patterned proton-exchanged process. The validity of the method is verified by the good agreement of the spectral responses and the Bragg phase-matching condition. Reflectivity as high as 94% at 1546 nm was measured with 4-mm distributed parameter waveguides in z-cut lithium niobate.

Photonic applications of lithium niobate crystals

“…(c) Bragg gratings can also be constructed for the extraordinary waves propagating in a Ti waveguide by PE formation [68]. After deposition of a Si 2 O layer on the sample surface, a Bragg grating pattern mask is produced by photolithographic techniques.…”

Narrowband Bragg reflectors in Ti:LiNbO 3 optical waveguides and implantation to optical modulators

“…The nearly constant attenuation α indicates that the grating waveguide loss is due primarily to field redistribution and absorption in the Si film rather than scattering from the grating. [11,15] which assumes ideal lossless waveguide grating, gives values that are slightly larger than those obtained experimentally for all the tested samples. This verifies that the presence of loss α affects the value of such a defined spectral width.…”

“…It is of particular interest for the development of integrated optics devices such as slow-wave electrooptic modulators [1][2][3][4], and has been implemented in making polarization mode dispersion compensators [5], waveguide lasers [6], and several other components that are attractive for wavelength division multiplexed (WDM) network applications. Various techniques have been used for making Bragg reflection gratings on optical waveguides in LiNbO 3 [7][8][9][10][11]. To reflect a light of specific wavelength λ, the period Λ of the grating must satisfy the Bragg condition Λ = m λ/2n, where m is the grating order, λ is the free space optical wavelength at the reflectance peak, and n is the effective refractive index of the guided mode [12].…”

Chalcogenide As<sub>2</sub>S<sub>3</sub> Sidewall Bragg Gratings Integrated on LiNbO<sub>3</sub> Substrate

“…On the one hand, lithium niobate (LiNbO 3 ) has become an attractive material for integrated optical applications because of its outstanding electro-optical, acousto-optical and optical transmission properties [15]. In LiNbO 3 substrate, high-quality channel waveguide can be made by annealed proton exchange (APE) [16] or by thin film titanium (Ti) diffusion [17]. The mode size of such channel waveguides is comparable with optical fiber, making their coupling loss extremely small.…”