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To promote the feasibility of using photonic crystals to enhance light extraction of light-emitting diodes (LEDs) for industrial applications, the request for the high-yield and simple exposure process to pattern two-dimensional photonic crystals (2DPCs) becomes rather urgent. In this work, we developed a one-shot three-beam laser interference system to fabricate a 2DPC on an InGaN-based green LED to address its performance for backlight display applications. Using the current exposure system we develop here, a submicro-patterned area of 6 mm in diameter can be achieved. The experimental results show that the operating voltage of a 1 times 1 mm2 in-area LED incorporated with the 2DPC is around 4 V, and the light extraction efficiency is enhanced by a factor of 2.1.

We demonstrate a new approach for fabricating a compact loss-tunable long-period fiber grating (LPFG) by gluing a fiber onto a corrugated metal substrate filled with ultraviolet-cured epoxy. The strain caused by the difference in thermal expansion among the adhesive, the substrate, and the silica fiber induces a periodic microbending along the fiber when the device temperature is changed. The LPFG has an initial flat spectrum at room temperature. With 35 grating periods, a tuning range of -21 dB is achieved through core-cladding coupling for a temperature change from room temperature to 4/spl deg/C. A theoretical model is presented to explain the high tuning efficiency and the operating mechanisms of the device.

We present a novel low temperature bonding technique for fabricating long wavelength vertical cavity surface emitting lasers (VCSEL's). The technique relies on a 750 /spl Aring/-thick intermediate spin-on glass layer to join a highly efficient InP-based InGaAs-InGaAsP strain-compensated multiple quantum well (SC-MQW) gain medium on a GaAs substrate. We fabricated the device on GaAs in order to take advantage of highly reflective AlAs-GaAs Bragg reflectors. The optically-pumped device has a low threshold pump power of 4.2 kW/cm/sup 2/ at room temperature and operates at a wavelength of 1.44 /spl mu/m. >

The effects of strain and number of quantum wells on optical gain, differential gain, and nonlinear gain coefficient in 1.55- mu m InGaAs/InGaAsP strained-quantum-well lasers are theoretically investigated. Well-approximated empirical expressions are proposed to model these effects. Using these formulas, one can easily and accurately predict the performance of a laser diode for a given structure. Therefore, these empirical formulas are useful tools for design and optimization of strained quantum well lasers. As a general design guideline revealed from the empirical formulas, the threshold current is reduced with the compressive strain, and the modulation bandwidth is most efficiently increased with the number of wells. >