Optimization And Design Of Arrayed Waveguide Grating Multiplexer/demultiplexer And Its Software Realization

With the development of modern telecommunication and networks, moreand more attentions have been paid to dense-wavelength-division multiplexing(DWDM) systems. And N×N arrayed waveguide grating (AWG) multiplexer hasbeen very attractive in optical DWDM networks since it is capable of increasingthe aggregate transmission capacity of single strand optical fiber. So, it becomesone of the key technologies in studying DWDM systems to fabricate AWGdevice and develop its performance. The AWG multiplexer consists of input/output rectangular waveguides (i.e.I/O channels), two focusing slab waveguides, and an AWG which containsnumbers of arrayed rectangular waveguides. The AWG joins the two slabs andprovides a constant length difference between adjacent arrayed waveguides. Inthis paper, the operation principle and fundamental characteristics are presentedaccording to the waveguide model equation and basic grating principle, such asangle dispersive, free spectral range (FSR), inching function, wavelengthdistributing, temperature response and so on. The request of the WDM systemsto AWG is wavelength stabilization, low crosstalk, low insertion loss, flatresponse bandwidth, easy integration and interconnection, low cost and easyencapsulation. The characteristics and its application in telecommunication andnetworks are analyzed and described. The single-mode optical waveguide is the basic element of optoelectronic 128吉林大学博士学位论文circuits and integrated optoelectronic devices including AWGs. Based on theelectric-magnetic theory, we introduced the Emn mode and E mn mode, and the y xwidth and the effective refractive index of the waveguide are given. According tothe results we have got, we optimized a polymer AWG multiplexer. First someimportant parameters are optimized for the structural design of a polymer AWGmultiplexer around the central wavelength of 1.55 μm with the wavelengthspacing of 1.6 nm. These parameters include the thickness and width of the guidecore, mode effective refractive indices and group refractive index, diffractionorder, pitch of adjacent waveguides, length difference of adjacent arrayedwaveguides, focal length of slab waveguides, FSR, the number of input/outputchannels, and that of arrayed waveguides. Then the bent angles, radii and lengthsof all the input/output channels and arrayed waveguides are determined. Finally,a schematic waveguide layout of this device is presented, which contains 2 slabs,11 input channels, 11 output channels, and 91 arrayed waveguides. The transmission characteristics play important roles in the application ofAWG to telecommunication. The transmission characteristics are analyzed for apolymer AWG multiplexer around the central wavelength of 1.55 μm with thewavelength spacing of 1.6 nm. We introduce the expressions of the normalizedfield of AWG according to the AWG diffraction theory. The power profile in theinput slab waveguide and output slab waveguide are analyzed, transmissionspectrum, diffraction efficiency, polarization and crosstalk are investigated anddiscussed for different values of parameters, such as the core width, pitch ofadjacent waveguides, the number of arrayed waveguides, propagatingwavelength and diffraction order. Larger core width and larger number of thearrayed waveguides lead to weaker background of the output power profiles andtransmission spectra of the device. Smaller pitch of adjacent waveguides, largercore width and larger diffraction order can result in higher diffraction efficiency.By using a taper to widen the input ends of the arrayed waveguides, thediffraction efficiency can be increased efficiently. There exists a minimum of thecrosstalk with the variation of the pitch of adjacent waveguides. Therefore, weshould select its value nearby this minimum to reduce the crosstalk of the device.