Waveguide Fabrication

Waveguide Fabrication Techniques Unique to Chromophore-Doped Polymers... 

Several methods can be used for waveguide fabrication in LiNbOs. Among them, titanium in-diffusion and proton exchange (PE) are the most popular ones since they lead to the formation of well-confined and low-loss layers. PE is mainly applied because it results in a considerable decrease of the photorefractive effect in LiNbOj. However, waveguides obtained by pure PE have reduced EO and NL coefficients and usually a post exchange aimealing (APE) is required for restoration of the EO activity. 

Three-dimensional wavelength demultiplexing has also been recently introduced as the multilevel extension of the planar AWG. It, however, suffers from difficulties in its packaging. On the other hand, the 3D MMl PHASAR is compatible with the planar waveguide fabrication technologies and has no special packaging problems. 

The refractive index of fluorinated polyimide can be controlled precisely by adjusting the election beam irradiation dose as described in Section 3.2.2, and this feature can be exploited in fabricating polyimide optical waveguides. This section describes fluorinated polyimide waveguides fabricated by the direct electron beam writing method. ... 

Structuring of polymer films attracts considerable attention, and various radiation sources have been employed to crosslink selectively suitable polymers for, e.g., waveguide fabrication [99], Incompatible polymer blends have been forced into certain demixing morphologies along pre-patterned surfaces [55], Persistent structures could be formed by laser radiation in various nonabsorbing polymer solutions, such as polyisoprene in n-hexane [57, 58],... 

Korishko YN, Fedorov VA, Feoktistova OY (2000) LiNbOS Optical waveguide fabrication by high-temperature proton exchange. J Lightwave Technol 18 562-568... 

TABLE 3. Propagation losses in glassy polymer waveguides fabricated by various techniques... 

Furthermore, half-ellipsoid voxels and half-cylindrical rod shapes were fabricated by TP polymerization where a single voxel was obtained by a laser power of 50 pW and an exposure time of 0.5 s [135]. The half-cylindrical rod shapes based on poly(methylmethacrylate) possess a higher reflective index compared to air of about 0.5. Hence, this material can be used as waveguide material. The channel waveguide fabricated using a scanning speed of 40 pm/s and an input laser power of 500 pW of a femtosecond laser beam with a 0.65 NA microscope objective exhibits a width of 2 pm. In a similar way, a grating was made with 10 lines per 50 pm [135]. 

J.W. Chan, T.R. Huser, S.H. Risbud, and D.M. Krol, Modification of the fused silica network associated with waveguide fabrication using femtosecond laser pulses, Appl. Phys. A, 76, 367-372 (2003). 

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