What we believe to be a new optical waveguide is introduced consisting of direct coupled diatomic microresonators, we call the diatomic coupled-resonator optical waveguide (CROW), where the inter-resonator coupling and/or the optical length of adjacent resonators alternate so that the unit cell comprises two resonators. We investigate this device analytically and numerically to find new transmission, group delay, dispersion, and switching characteristics, including a subsidiary stop band within the passband, a result of the alternating resonator parameters, whose width and extinction ratio are directly related to the parameter perturbation, displaying the signature characteristics associated with a finite Bragg grating. Analytical expressions are derived for the band-edge frequencies and the subsidiary stop band width, and numerical simulations illustrate the extent of versatility of the diatomic CROW design, including dispersion slope manipulation. The use of a simple matching structure terminating the diatomic CROW is found to significantly improve the device performance. The sensitivity of the diatomic CROW to the resonator loss is investigated and fabrication issues are also addressed.
© 2010 Optical Society of America
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