Investigations of laser oscillation and switching using a resonance at the band edge crossover in an hetero-structure of one-dimensional photonic crystals

This paper presents a theoretical investigation of a laser oscillator and a laser switch, using a hetero-structure made of two one-dimensional photonic crystals with active materials and a period ratio of r (r > 1). Lasing is achieved near frequencies where the upper and lower band edges of the adjacent photonic crystals overlap (i.e., band edge resonance). Near the band edge resonance, two modes of laser oscillations are found; mode A – the threshold gain increases with r and mode B – the threshold gain decreases with r. By assuming a homogenously broadened gain medium at any particular r, only one of the two modes is able to participate in lasing. We also found the lasing mode is switchable upon a very small alteration in the refractive index of the materials present in the photonic crystal. The results of the paper will be very useful for designing a new class of tunable lasers and high sensitivity sensors.