Ultra High-Q Photonic Crystal Nanocavities Based on Compound Semiconductors
Akihiko Shinya1, Shinji Matsuo2, Yosia1, Takasumi Tanabe1, Eiichi Kuramochi1,
Takehiko Tawara1, Kouta Tateno1, Tomonari Sato2, Takaaki Kakitsuka2, and Masaya Notomi1
1Optical Science Laboratory, 2NTT Photonics Laboratories
Photonic crystal (PhC) is a promising candidate as a platform to construct devices with dimensions of several wavelengths. A PhC is an artificial structure with light wavelength periodicity that can confine light in an ultra small area of about 0.1 µm3 with an ultra high Q factor. We have been studying ways of strongly confining light in ultra small areas with the aim of minimizing the light propagation speed and enhancing the light-material interaction by using Si based PhCs. In this report, we adopt new materials, namely InGaAsP and AlGaAsP, to develop a new photonic technology. These materials have certain features that Si does not have, e.g. they exhibit large refractive index modulation owing to optical nonlinearity, and they are expected to be used for PhC based active devices.
Figure 1 shows a scanning electron micrograph of an InGaAsP PhC and transmission spectra of InGaAsP and AlGaAs PhC nanocavities. The PhCs are composed of air holes arranged 420 nm apart in a triangular pattern and they function as a light insulator at a wavelength of around 1.55 µm. The area with no linearly arranged holes is the light waveguide and the area where some holes are shifted few nanometers away from the center of the waveguide functions as a cavity that can confine light . InGaAsP and AlGaAs PhC nanocavities have estimated Q factors of 130,000 and 690,000, respectively. These values are around ten times larger than those previously reported for PhC nanocavities with these materials. They are expected to provide all-optical memories with very low operating power  and highly efficient optical-mechanical power converters .
This work was supported by the National Institute of Information and Communications Technology (NICT).
 E. Kuramochi, et al., Appl. Phys. Lett. 89 (2006) 241124.
 T. Tanabe, et al., Opt. Lett. 30 (2005) 2575.
 M. Notomi, et al., Phys. Rev. Lett. 97 (2006) 023903.
Fig. 1. PhC cavity structure and transmission spectra of InGaAsP and AlGaAs PhCs.
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