Design of high-Q microcavities for proposed two-dimensional electrically pumped photonic crystal lasers

Electrically pumped photonic crystal lasers are of practical importance for future integrated photonic circuit systems. This paper proposes a methodology for achieving high quality (Q) factor photonic crystal defect cavities that allow current injection into their active regions. It is shown that by combining certain high Q-factor photonic crystal cavity designs with the technique of wet oxidation of (Al,Ga)As layers, Q factors of up to ∼10⁴ can be obtained within the scope of existing semiconductor planar process technology. The proposed device structures can be optimized through use of finite-difference time-domain methods to obtain optimal separation of the high refractive index substrate from the active core; furthermore, the effects of the top ohmic contact layer, the top and bottom cladding layers of the structure, and the current injection opening can be taken into account to achieve an optimal Q factor in electrically pumped lasers.