| New optical coupler devices have been designed with both analytical and numerical simulation tools. Using these tools, design rules were derived for both 3dB and full adiabatic couplers. The design rules are in excellent agreement with numerical calculations using the beam propagation method (BPM). It is shown that the length scaling for the 3dB adiabatic couplers compared to full adiabatic couplers makes the former more difficult to design. The design in each case is optimized to obtain an upper limit of performance. A comparison is carried out between two different design geometries to select the optimum adiabatic coupler design which requires the shortest length for a given coupler performance. An improvement in, the fabrication tolerance of the optimum design has yielded a new more-tolerant 3dB adiabatic-coupler, which is distinguished by a coupler region where both waveguide width and separation are tapered.; A novel 1 x 4 coupler-multiplexer permutation switch (CMPS) is proposed for applications in wavelength-division-multiplexing (WDM) networks. The CMPS integrates the functions of a 1 x 4 multiplexer followed by a 4 x 4 switch-array in a single compact device. It consists of a single-mode/multimode-waveguide grating-assisted backward-coupler multiplexer followed by a digital optical switch (DOS). Two different InP-based designs of the CMPS, which use InGaAsP/InP multiple-quantum well (MQW) output waveguides, are introduced. In both of these designs, the CMPS channels are unequally spaced which reduces unwanted four-wave mixing.; Finally the electro-optic response is measured in single-crystal LiNbO 3 thin films obtained by crystal-ion-slicing (CIS). This technique uses ion implantation of singlecrystal bulk samples followed by selective etching. Post liftoff annealing (PLA) is shown to be a key step in improving the light transmission properties of these films for hybriddevice applications. It is shown that PLA must be used, as opposed to pre-liftoff annealing, in order to eliminate the change in modal attenuation, which is created upon liftoff. This attenuation mismatch, explains the poor performance of CIS films before annealing, and is attributed to stress-induced rather than implantation-induced effects. |
