High performance dense wavelength division multiplexing/demultiplexing based on blazed grating and ion-exchanged glass waveguide technique
Dense Wavelength Division Multiplexing (DWDM) is one of the key technologies in today’s high bit rate optical communications. In this dissertation, we conducted research on blazed grating based DWDM devices, which are advantageous over other WDM technologies in many aspects. Theoretical analysis showed that three major challenges exist for the grating based DWDMs, i.e., pulse broadening, 1dB passband and device dimensions. Specifically, the pulse broadening induced by the optical path delay of grating is a bottleneck for data bit rate. To overcome these challenges, we proposed integrating an ion-exchanged glass waveguide fan-out chip into the DWDM. In order to fabricate this single-mode fiber-compatible waveguide fan-out, both purely thermal ion exchange and field-assisted ion exchange have been investigated. Waveguide properties under different fabrication conditions were compared for optimization. With the optimized field-assisted process, we obtained waveguides with propagation loss and mode mismatch to SMF of 0.16dB/cm and 0.1dB, respectively. Based on this ion exchange process, we designed and fabricated the waveguide fan-out chip that contains 48 S-bend channel waveguides. This waveguide fan-out was then successfully bonded with a standard 48-channel SMF fiber array, with an average total insertion loss of 0.7dB for each channel and very good uniformity. Finally, a 48-channel 100GHz-spacing DWDM centered at wavelength of 1550nm was designed and demonstrated. The performance of this DWDM device has verified the effectiveness of the proposed solution and the successfulness of the ion-exchanged glass waveguide technique.