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Posted: Apr 08, 2011

Researchers report a novel nanoscale integrated all-optical diode

(Nanowerk News) Recently, new achievements were made in the integrated optics by the Creative Research Group of Femtosecond Photophysics & Integrated Optics at Peking University. The group realized a novel nanoscale integrated all-optical diode having ultralow power and ultrahigh transmission contrast after the realization of the all-optical switch device with ultralow power and high-speed photonic crystal.
The related research paper, titled "Low-Power and High-Contrast Nanoscale All-Optical Diodes Via Nanocomposite Photonic Crystal Microcavities", has been published in the journal Advanced Functional Materials.
The photonic crystal all-optical diode is one of the important integrated photonic devices, which has potential applications in the fields of optical computing, optical interconnection systems, and integrated photonic circuits. Low operating power and high transmission contrast are the two key characteristics for the photonic crystal all-optical diodes. Owing to the relatively small nonlinear optical coefficients of the conventional optical materials, the operating threshold power is rather high with a threshold intensity of several hundred GW / cm2. Moreover, the transmission contrast was achieved only less than 100. This has greatly restricted the practical applications of the photonic crystal all-optical diodes.
By combining the strong plasmonic response of metal nanoparticles and the strong photon confinement effect of photonic crystal microcavity, the group has constructed a nanocomposite photonic crystal microcavity with very large third-order nonlinear susceptibilities. A prototype device of photonic crystal all-optical diode is realized based on the effect of surface-plasmon resonance enhancing optical nonlinearity and dynamic coupling of asymmetrical microcavity modes. An ultralow threshold photon intensity of 2.1 MW / cm2 and an ultrahigh transmission contrast of 11875 are achieved simultaneously. Compared with previously reported all-optical diodes, the operating threshold power is reduced by four orders of magnitude, while the transmission contrast is enlarged by three orders of magnitude.
The research achievement will not only promote the practical application research on the integrated photonic devices like all-optical diodes, but also provide a new approach for the study of nonlinear optical material.
This work is supported by the National Basic Research Program of China (973 Program) and the National Nature Science foundation of China (NSFC).
Source: Peking University
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