Extremely small multimode-interference coupled triangular resonator with sharp angle of incidence.

Novel triangular ring resonators combining extremely small multimode-interference (MMI) coupler, low loss total internal reflection (TIR) mirrors, and semiconductor optical amplifiers are reported for the first time. The MMI length of 90 microm is among the shortest reported. The incidence angle of the TIR mirror inside the resonator is 22 degrees. A free-spectral range of approximately 2 nm is observed near 1550 nm along with an on-off ratio of 17 dB. The triangular resonators with a sharp angle are very attractive components due to their promise of compact size and high levels of integration. Therefore, large numbers of resonators can be integrated on a chip to increase functionality in future optical wavelength division multiplexing system.

Design of monolithically integrated vertical cavity laser with depleted optical thyristor for optical programmable gate array.

We have theoretically analyzed the depleted optical thyristor structure and experimentally demonstrated optical logic gates implemented by monolithically integrated vertical cavity laser--depleted optical thyristor (VCL-DOT) for an optically programmable gate array. The optical AND-and OR-gates have been realized by changing a input bias of the single VCL-DOTs and all kinds of optical logic functions are also implemented by adjusting an intensity of the reference input beams into the differential VCL-DOTs. To achieve the high sensitivity and low threshold current, a small active region of lasing part and a wide detecting area are simultaneously designed by using a selective oxidation process..

Simultaneous noise and distortion reduction of a broadband optical feedforward transmitter for multi-service operation in radio-over-fiber systems.

The broadband optical feedforward transmitter with uncooled and unisolated distributed-feedback laser diodes (DFB LDs) is developed for a radio-over-fiber system. Although we use DFB LDs for digital communications, the feedforward compensation method can significantly suppress the intermodulation distortions and background noise. For the wide frequency range from 2.05 to 2.60 GHz (550 MHz), the third-order intermodulation distortion (IMD3) is suppressed by more than 10 dB. We also analyze the variation of IMD3 and noise for the bias current of LDs. With the linearization technique, the maximum IMD3 suppression and spurious-free dynamic range enhancement are 21.3 dB and 7.11 dB, respectively, at 2.3 GHz.

Optical AND/OR gates based on monolithically integrated vertical cavity laser with depleted optical thyristor structure.

Latching optical switches and optical logic gates with AND and OR functionality are demonstrated for the first time by the monolithic integration of a vertical cavity lasers with depleted optical thyristor structure. The thyristors have a low threshold current of 0.65 mA and a high on/off contrast ratio of more than 50 dB. By simply changing a reference switching voltage, this single device operates as two logic functions, optical logic AND and OR. The thyristor laser fabricated by using the oxidation process and has achieved high optical output power efficiency and a high sensitivity to the optical input light.