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wdm optical interfaces for future fiber radio systems phần 8

Tham khảo tài liệu 'wdm optical interfaces for future fiber radio systems phần 8', kỹ thuật - công nghệ, kĩ thuật viễn thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 5 Enabling Wavelength Interleaving in Millimetre-Wave Fibre-Radio Networks 5.4.1.5 Free Spectral Range As stated above FSR of a periodic AWG is defined as the frequency separation between adjacent passband positions of a given port and it happens to be normally equal to the product of the number of input output waveguides and the frequency separation between two adjacent channels FSR N.ẠẠ Therefore FSR of the 8 X 8 Wavelength nm Fig. 5.7 Measured combined optical spectra at the outputs of the AWG generated using the ASE of an EDFA covering three FSRs of the AWG used. AWG under investigation is 100 GHz. FSR of any AWG can be measured by connecting a broadband light source such as asynchronous spontaneous emission ASE from erbium-doped-fibre-amplifier EDFA to any input waveguide and measuring the output at any output waveguide. Multiple periodic peaks can be seen with a periodic channel separation of N.A However in some instances due to design and fabrication constraints especially while adjacent channel separations 195 Chapter 5 Enabling Wavelength Interleaving in Millimetre-Wave Fibre-Radio Networks between the waveguides are very low the periodic property of the AWG is enabled to repeat after multiple of FSRs n x FSR instead of each FSR. The device under investigation is a such type of AWG where periodic properties were enable to repeat after 5 multiple of FSRs FSR 100 GHz . The spectra at the output waveguides of the 8 X 8 AWG with three periodic peaks are shown in Fig. 5.7. The noise level between the periodic peaks is the indication of crosstalk. Therefore the AWG under investigation can only support periodic frequencies which are at multiple of 500 GHz although FSR of the device is 100 GHz. 5.4.2 Experimental Demonstration of the Proposed WI-MUX This section presents the experimental demonstration of the wavelength interleaved multiplexer proposed in Section 5.4. The 8 X 8 AWG characterised in OSSB Mod. WI-MUX PC ị I Ị S1 C1 S2 C SC nA Dd A2 B2 A3 B3 .