ABSTRACT
As an essential integrated photonic device, photonic crystal laser plays a very important role in the fields of all-optical computing, optical communication, and ultrahigh speed information processing. Photonic crystal possesses unique photonic bandgap properties, which can effectively prohibit the spontaneous radiation, which makes it possible to achieve a thresholdless laser [1]. The dream of thresholdless laser has inspired people to make great efforts in the fields of low-power photonic crystal laser. The simplest photonic crystal laser uses two one-dimensional photonic crystals as high reflection mirrors to construct a microcavity. When the active material was filled in the microcavity structure, a photonic crystal laser can be reached [2]. This approach often leads to a large size of the photonic crystal laser. The micro/nano laser could be realized in two-dimensional photonic crystals based on the photonic bandedge effect or defect states [3]. In the photonic bandgap, the photon state density is zero. The value of photon state density rapidly increased from zero to a large magnitude in the photonic bandedges and the center of defect modes. Moreover, the group velocity vg of electromagnetic waves almost approaches zero in the photonic bandedges and the center of the defect modes, which enhances the lifetime of photons and interactions of light and matter greatly. These two factors indicate
that the Bloch waves in the photonic crystal can provide a strong and intrinsic feedback mechanism in the photonic bandedge and defect states for the realization of laser oscillation [4].
