Studies On Low-loss Flat-field Arrayed Waveguide Grating

Arrayed waveguide grating (AWG) is of great importance to the future dense wavelength division multiplexing (DWDM) all optical network (AON). In this dissertation, new-type and special-type AWG schemes are studied, the low insertion loss design method is discussed and a novel high-efficiency fiber-to-waveguide coupler is presented. The researches on the fabrication of a polymeric AWG are also reported.Based on the aberration theory of AWG, a new-type flat-field AWG is designed. The focal signals of all wavelengths of operation are focusing along a straight line perpendicular to the propagation direction. Three stigmatic points restrain three dominant geometry parameters. Furthermore, a new-type flat-field wavelength router with both flat input field and flat focal field is also designed.A novel integrated DWDM interleaver scheme is presented based on double-channel AWG with multimode interference (MMI) couplers instead of standard Rowland-circle star couplers. MMI-AWG interleaver can realize narrow channel spacing through simple design procedure. It's simple in structure, compact in size, and convenient for integration with integrated planar waveguide multi/demultiplexers.The insertion loss of AWG is analyzed and the low-loss design method is discussed. A low-loss polymeric flat-field AWG is designed by optimizing the structure and geometry parameters.An integrated diffractive optical mode converter scheme is presented to eliminate the mode mismatch between optical waveguide and single mode fiber (SMF). Then, a high coupling efficiency can be achieved. The diffractive optical element (DOE) is designed using iterative phase retrieval algorithm. In the iterative algorithm, a new modification of far-field amplitude constraint is introduced to provide very high mode-conversion quality. The scheme is applicable for low-loss coupling between SMF and any type of waveguide structure. And it's also applicable for efficiently coupling SMF with semiconductor laser diode (LD) of any aspect ratio of the elliptical field.For the first time, a new-type flat-field AWG is fabricated using electron-beam direct writing based on polymeric optical waveguide. The waveguide core-layer material is a newly-developed negative tone epoxy Novolak resin (ENR) polymer. The polymeric flat-field AWG sample is tested by an optoelectronics passive device test set. The feasibility of the fabrication technique is prelimimarily proved. The performance deteriorations due to fabrication errors are analyzed. And besides, a silica-based standard Rowland-circle AWG sample is also tested and compared with the polymeric one.