| Single-atom laser or maser,in which no more than one atom or a quantum dot is in interaction with the quantized field of high-Q microcavity,is an important tool for the investigation of novel quantum electrodynamic effects。It has aroused widespread interest and concern since one atom microlaser was first realized experimentally in 1985。At present,research in the area of the laser theory is mostly focused on single-atom lasers and their practical applications in photonics,nano and quantum technologies。In this paper,We study the statistical properties of the cavity field for dressed-atom laser in a photonic band-gap material。We demonstrate the capability of complete thresholdless lasing operation between dressed states of a two-level atom located inside a microscopic cavity engineered in a photonic band-gap material。We distinguish between threshold and thresholdless behaves by analyzing the Mandel' s Q parameter for the cavity field。We find that the threshold behave depends on whether the spontaneous emission is or is not present on the lasing transition。In the presence of the spontaneous emission,the mean photon number of the cavity field exhibits threshold behavior indicating that the system may operate as an ordinary laser。When the spontaneous emission is eliminated on the lasing transition,no threshold is observed for all values of the pumping rate indicating the system becomes a thresholdless laser。Moreover,we find that under a thresholdless operation,the mean photon number can increase nonlinearly with the pumping rate,and this process is accompanied by a sub-Poisson statistics of the field。This suggests that the nonclassical statistics can be used to distinguish a nonlinear operation of the dressed-atom laseroWe also investigate the radiative characteristics of the system,the spectral features are interpreted in terms of transitions among these dressed states of doubly dressed atom,and we analyze the influence of a photonic crystal on the spectrum of resonance fluorescence and the output spectrum of the cavity for the system。As the change of the detuning between the atomic transition frequency and the laser field frequency ,the structure of cavity field spectra and atomic fluorescence spectroscopy have experience from the double-peak spectrum to the multi-peak spectrum,and then to the single-peak spectrum。These detailed structure depend on the atom-cavity coupling,the cavity decay and spontaneous emission and the photon-number distribution of the cavity mode。So it can provide a nonintrusive measurement of the photon-number distribution of the cavity field by measuring the spectrum of the system。Moreover,we can get stronger,narrower and more spectrum in photonic crystal。Our study reveals new and enhanced,spectrally narrower emission resulting from the radiation reservoir of the photonic crystal。Under the condition of the detuing withδ(?)0,we find the linewidth in photonic crystal is six percent of the microcavity in ordinary vaccum。Whose linewidths are each smaller than the natural linewidth and cavity decay rate。... |
