Highly Directive and Broadband Radiation From Photonic Crystals With Partially Disordered Cavities Arrays

Two-dimension hexagonal photonic crystals (PhCs) with ordered and partially disordered cavities arrays, such as missing holes, were studied using numerical modeling by the 3-D finite-difference time domain method. First, we examined an obvious case of PhCs with the ordered array of 19 coupled cavities which produce a highly directive and 19 times enhanced emission, while the single peak radiation mode and the peak wavelength width remain about the same as those for the PhC with a single cavity. The modified PhC with a partially disordered cavities array is found to emit a three times broader peak than that of the single-cavity PhC, saving the integral peak intensity and highly directive emission. These are the results of the constructive cavities-coupling radiation interference. The found peak-broadening effect may lead to efficient broadband Si-based light emitters fabrication. This is interesting for numerous sensing applications, including fiber Bragg grating interrogation.