We have designed and integrated a high density micro-ring resonator and photonic crystal waveguide array for wavelength division multiplexing (WDM) microsystem applications. First, we designed and optimized micro-ring resonators. Using the non-unitary transfer matrix method (NU-TM), we have been able to analyze the transfer characteristics of the micro-ring and micro-racetrack resonator system. The track-length dependence, which is not obvious in the unitary transfer method (U-TM) analysis, is clearly found in the NU-TM analysis. By optimizing the WDM filter characteristics such as FSR (Free Spectral Range) and cross-talk, we have found the optimal dimensions, such as length, of the racetrack resonator. And then for improving the WDM filter characteristics of microring resonator, we have designed bent photonic crystal waveguide. Integrating microring resonator with bent photonic crystal waveguide can offer additional functions such as band pass filtering function.
We show that the self-imaging principle still holds true in multi-mode photonic crystal (PhC) line-defect waveguides just as it does in conventional multi-mode waveguides. To observe the images reproduced by this self-imaging phenomenon, the finite-difference time-domain computation is performed on a multi-mode PhC line-defect waveguide that supports five guided modes. From the computed result, the reproduced images are identified and their positions along the propagation axis are theoretically described by self-imaging conditions which are derived from guided mode propagation analysis. We report a good agreement between the computational simulation and the theoretical description. As a possible application of our work, a photonic crystal 1-to-2 wavelength de-multiplexer is designed and its performance is numerically verified. This approach can be extended to novel designs of PhC devices.
We present a new approach in the design of a photonic crystal bandpass filter by using waveguide bending. The bandpass filter was designed by introducing two bends with the modified geometry into the both ends of a photonic crystal waveguide. We show that such a filter exhibits step-like spectral profile in the range of 1500-1600 nm, with a maximum transmission of 100%. In contrast to the other designs proposed, the present one does not involve either insertion of small defects or control of cavity-lengths.