| Summary: | 博士 === 國立臺灣大學 === 電機工程學研究所 === 90 === Vertical Cavity Surface-emitting Laser has become important light source for the optical data communication and optical interconnects, due to their advantageous properties such as low threshold current, low divergence circular beam, one and two- dimensional array. In recent years, the 850nm VCSEL has been adopted in giga-bit-Ethernet for local area network (LAN). In most applications, the VCSEL with a stable single mode and stable polarization are important for low-noise, data rate communication, optical storage, and printing systems. Stable polarization can reduce noise and result in the better bit-error-rate (BER) performance of optical transmission system, while single mode operation can maximize the modulation bandwidth.
In this thesis, we develop a viable method to fabricate the single mode and stable polarization 850nm vertical-cavity surface emitting lasers. In addition to the conventional oxide or ion-implanted confinement aperture, our method introduces a shallow zinc diffusion (~0.5μm) optical aperture in the VCSELs structure. The fabricated devices operate at a stable single mode and stable polarization over the entire drive current range. The VCSEL with an optical aperture of 5x5μm2 and an active region diameter of 15x15μm2 is demonstrated. The threshold current is ~3mA, the output power is ~3.5 mW , and variation of the threshold currents is less than 1mA. The VCSEL operates at the single transverse mode up to a high bias current level at the temperature range from 00C to 700C with a side mode suppression ratio (SMSR) greater than 30dB.
For polarization control in VCSELs, we have demonstrated two methods to achieve stable polarization in VCSELs. First method employs the intrinsic anisotropic of the DBR grown on the (001) on-axis substrate by MBE. Stable polarization along [011] direction can be produced. The second one using the rectangle zinc diffused aperture to control the polarization direction along the long side of the aperture.
The structures proposed in this thesis provide us a viable way to fabricate the suitable light source for both discrete and OEIC’s applications.
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