Waveguide birefringence

Fig.4. Schematic representation of the different common phase-matching techniques in the k space representation. (ADM) anomalous dispersion (WBM) waveguide birefringence (MD) modal dispersion (QPM) quasi-phase-matching (C) Cerenkov and (CP) counter propagating Cerenkov...

Lagorceix, H., Reynaud, R, 1995, Squeezing highly Birefringent Fiber for an Accurate Nondestructive Determination of Principal-Axis Orientation along the Waveguide application to Fiber Babinet Compensator Implementations Optical Fiber Technology 1, 171... 

Figure 10. Calculated variation with cladding thickness of the birefringence in a SOI ridge waveguide, for different Si02 cladding film stress values. The model waveguide is formed in a 2.2 [j,m thick Si layer and has a typical trapezoidal wet etched ridge profile, with a base width of 3.8 pm, a top width of 1.1 pm, and an etch depth or 1.47 pm.

Figure 11. Comparison of calculated and measured birefringence for different Si02 cladding thicknesses for a trapezoidal waveguide formed in a 2 im thick Si layer as shown in the inset. The ridge base width is 3.8 p,m, the top width is 1.1 pm, and the etch depth is 1.47 pm.

W.N. Ye, D.-X. Xu, S. Janz, P. Cheben, M.-J. Picard, B. Lamontagne, and N.G.T. Tarr, "Birefringence control using stress engineering in sihcon-on-insulator (SOI) waveguides," IEEE J. Lightwave Technol. (in press, 2005). 

The natural way to increase the efficiency of such a frequency conversion process is to use a focused fundamental beam (or, alternatively, a waveguide structure). An established theory of SHG using focused cw beams " predicts, for negligible birefringence waUc-off, an optimal focusing condition which is expressed by the ratio L/b 2.83, where b is the confocal parameter (b = k wQ, where Wqi and ky are the focal spot radius and the wave vector of the fundamental wave respectively). However, this theory applies only to the long-pulse or cw case, where GVM is negligible... 

The refractive index must be precisely controlled because it is essential for optical components such as single-mode optical waveguides. This control can be achieved by copolymerization of low- and high-refractive-index polyimides. Birefringence control can be achieved by a film elongation technique using a particular polyimide. 

This chapter describes the synthesis of partially fluorinated polyimides for optical teleconununications applications," " 2 their optical transparency (optical loss), refractive index, and birefringence properties" in addition to their fundamental properties. It also describes their device application as optical interference filters," " optical waveplates," and optical waveguides." -" ... 

The experimental value reported for PDN6S in Table V is very preliminary and is based on only three experimental points derived from prism-coupled waveguide reflectivity measurements. At this point, spurious effects due to heating, photoinduced birefringence etc. can not be conclusively ruled out. This preliminary data is presented only to provide a comparison with the calculated value. 

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