Study Of Boa-type Optical Switch With Double-Heterostructure GaAs/GaAlAs

All-Optic-Network based on OXC and OADM needs high-speed optical switch to realize photonic switching. Due to high switching speed, waveguide optical switch will be applied widely to optical switching systems. It is urgent and important to develop waveguide optical switch with high performance.In this dissertation, a BOA-type waveguide optic switch with double-heterostructure GaAs/GaALAs has been researched. GaAs-based integrated optical devices have good temperature, good anti-radiation and optical-transmission characteristics, and also have wide transparent range of wavelength. They can also be integrated on a chip with optical active devices and electronic devices, such as semiconductor laser, optical modulation, optical amplifier, PIN, and so on. The optical switch with double-heterostructure GaAs/GaALAs has low switching-voltage and light loss. And the BOA-type optical switch utilizes maximum modal dispersion (A P ), does not require a specific fabrication length or length range to operate, has simple structure, and can exhibit very high extinction-ration from its two output ports; So it is suitable for a 2 X 2 unit of optical switch array. In this dissertation, the BOA device with high extinction-ration, low drive-voltage, high-speed switch and insensitive to wide range of light wavelength, has been developed on double-heterostructure GaAs/GaAIAs.In this dissertation, the design of the BOA-rype waveguide optical switch mainly consists of two parts:1. The design of rib waveguide and structure. Analyzing the characteristic of rib waveguide, we obtain that the loss of different modes (TE or TM mode) is different in the dual-zone of up-electrode. So, it can be used as TE/TM mode polarizer to eliminate the polarization of input light by meanings of optimal design of rib waveguide. A S-bend symmetric Y-branch has been proposed to obtain lower light transmission loss.2. The design of electrode structure. The relationships between extinction-ration, half-wave voltage and electrode structure have been analyzed with transfer matrix theory and effective index method. The following conclusions have been made: 1). The electrode width can be optimized to get the lowest half-wave voltage of BOA-type optical switch. 2). The symmetry of electrode is crucial forthe extinction-ration. Results show: To gain extinction-ration greater than 40dB, the offset of electrode position should be less than 0.3 micron. 3). A process so-called Self-adjustable Technics has been proposed to get high extinction-ration. With adopting the technics, the BOA device fabricated will have the excellent symmetry of electrode and the high extinction-ration (>40dB). According to our theoretic analysis and the realistic fabricating condition, the BOA device with double-heterostructure GaAs/GaALAs has been proposed to obtain 3dB bandwidth greater than 2.5 GHz, half-wave voltage about 5V, extinction-ration less than -40dB, transmission loss of TM mode greater than 45dB and transmission of TE mode less than 0.15dB.To obtain higher switching speed, we proposed that traveling-wave electrode is applied to BOA device. The traveling-wave electrode BOA-type device has been analyzed with Spectrum Domain Method. The results show: The BOA device of N+-doped substrates can not obtain the velocity-match between the lightwave and microwave due to the slow-wave and skin effect of N+-doped substrates; we can choose the thickness of N^-doped layer on the S.I. substrates so as to give a microwave index close to the optical index, thus the high bandwidth and high switching speed of the BOA device can been gained; Combining the characteristics of the BOA device, we proposed a traveling-wave electrode BOA-type device of 3dB bandwidth greater than 20GHz.On the basis of the theoretical analysis, design and the study on the fabricating technique, we have made the fabrication of the chip using the self-adjusted technics. The size of the chip is within 15xlmm2. The shape of the optical switch unit satisfied our design. Because of the limitation of the m...