Photonic Devices Based on In-Plane Hetero Photonic Crystals

Photonic crystals (PCs) are optical materials of periodic refractive index, designed to block light of certain wavelengths. Artificial defects such as line- and/or point-defects can be introduced into PCs to allow light to be manipulated. Ultra-small photonic devices, with sizes 1/1000 to 1/10,000 of those of conventional optical devices, are expected to be realized by using optical coupling among the artificial defects. However, devices with convincing performance have yet to be realized. This is due, in part, to the immature nanofabrication technique of PCs, but mainly due to a lack of a general design rule to obtain optimum performance for a broad range of wavelengths. Because performance is determined by a balance of various optical couplings among artificial defects, changing the resonant wavelength of just one point-defect to tune the operational wavelength, the balance can be seriously affected and the performance reduced. We demonstrate the ability to produce in-plane arrays of multiple PCs with proportional unit-cell sizes, in-plane hetero PCs (IP-HPC), to address the above issues and to fabricate an ultra-small channel add-drop functional device as an example. It is also shown that the hetero interface plays an important role to improve the device characteristics. (Author)