tailieunhanh - Advances in Optical and Photonic Devices 2011 Part 10

Tham khảo tài liệu 'advances in optical and photonic devices 2011 part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 214 Advances in Optical and Photonic Devices recognize. However by regarding the null-output port as the port indicating the address the address can be recognized. The maximum output intensity Pic rnax and the second smallest output intensity are plotted in . The decrease of Plc min and the increase of Plc max limit the recognized address bits. These values are -12dB and 18dB respectively for 5-bit addresses. Fig. 11. Comparison of the contrast ratio of the outputs for two cases. Fig. 12. Relative output intensity of the maximum output and the second smallest output for the second case of a 2 -1. The recognition characteristics were verified with computer simulation by FD-BPM. A twodimensional model of the 2-stage device for label length three is shown in . The waveguide circuit is assumed to be made of slab-type Ge-doped silica waveguides. The refractive indices of the core and the cladding regions are and respectively at wavelength 1550nm. The core width is l V 3 for the input waveguides 1 and 2 l V3 .im for the wider waveguide 3 and V4 for the narrower waveguide 4. The effective indices are calculated to be Nw and N at Ằ 1550 nm from the dispersion equation of guided waves. The crossing angle 0 is . The parameter w of eq. 7 is then evaluated to be . This value is enough larger than and the routing function of eq. 6 is expected. The hatched waveguides with width l V and Vl . are introduced to compensate the path-length difference. The total device length L is 20mm. The BPM simulation was performed for TE mode. Examples of the results for address 00 and n0 with a2 1 are shown in where the intensity profiles is shown. The incident fields to Integrated-Optic Circuits for Recognition of Photonic Routing Labels 215 I1 I2 and I3 are assumed to be ej0 eJ0 and 1 V2 ej0 for address 00 and eJ0 ej and 1l42 ej0 for address n0 respectively. The results agree well with the .