A study on optical microring-resonator for optical wavelength filter

The rapidly increase in demand for bandwidth from end users forces network infrastructure to be replaced by Dense Wavelength Division Múltiplexing (DWDM).

Some key devices for DWDM are add/drop filter, multiplexer and demultiplexer.

This dissertation provides study on using microring-resonators for wavelengtlı- selective devices such as add/drop filters, demultiplexers or multiplexers. Since wide free spectral range (FSR) in wavelength-selective devices is required to cover large channel counts, we proposed the new structure to expand FSR without decreasing radius of microring-resonator, and it is called as multi-path ring-resonator (MPRR). The investigation result shows that MPRR has better performances compared with other proposed structures such as double-cavity ring-resonator (DCRR) or triple- coupler ring-resonator (TCRR). Under assumption of proton-exchanged LN waveg- uide, for a typical expansion factor of 10, crosstalk of-18dB with low ripple ratio of~0.2dB and -1dB-bandwidth of 4GHz are obtained in this study. The device size is also~50% smaller than DCRR BPPT This dissertation also presents comparison study of serial and parallel-cascaded

microring-resonator when they are used as interleavers. In serial-cascaded, the 3- stage is the best choice if there are limitation on crosstalk (≤ -20dB), ripple ra- tio (≤ 1dB) and insertion loss (≤ 2dB). Optimization result shows that -1dB- bandwidth of 22GHz is obtained in 3-stage serial-cascaded for above requirements. With parameters on this condition, risetime of 30ps and settling time of 220ps are observed. Comparison with the saine order of parallel structure (3-stage parallel- cascaded), 3-stage serial-cascaded shows advantages of bandwidth and crosstalk per- formances but not in insertion loss and response time. For crosstalk requirement <-20dB, 3-stage parallel-cascaded shows-1dB-bandwidth of 12GHz, settling time of 60ps and risetime of 30ps. For the system permitted insertion loss ≤ 2dB, 3-stage parallel-cascaded permits waveguide loss ≤ 9.6dB/cm, but 3-stage serial-cascaded permits waveguide loss ≤ 4.2dB/cm.