Abstract. Laser induced line narrowing effect, discovered more than thirty years ago, can also be applied to recent studies in high resolution spectroscopy based on electromagnetically induced transparency. In this paper we first present a general form of the transmission width of electromagnetically induced transparency in a homogeneously broadened medium. We then analyze a Doppler broadened medium by using a Lorentzian function as the atomic velocity distribution. The dependence of the transmission linewidth on the driving field intensity is discussed and compared to the laser induced line narrowing effect. This dependence can be characterized by a parameter which can be regarded as "the degree of optical pumping". : 32.70.Jz, 42.50.Gy, Over the last decade, considerable attention has been paid to the studies of the atomic coherence effects and their applications [1,2]. The technique of Electromagnetically Induced Transparency (EIT) which makes an opaque medium become transparent by applying an external coherent radiation field [3,4], yields various applications from enhancement of nonlinear optical processes [5][6][7], to slow light [8][9][10][11][12][13][14]. In addition to the elimination of absorption, the absorption profile reveals a narrow transmission line, which has been applied to high resolution spectroscopy and high sensitivity magnetometer [15][16][17][18]. PACSSince many of these experiments are performed in an atomic cell configuration, the Doppler broadening effect on EIT is an important concern. Recent theoretical investigations of Doppler broadening effects on EIT, however, has been focused mainly on the existence of EIT for certain configurations [19][20][21]. The issue of EIT linewidth for a Doppler broadened medium has been lately addressed by Taichenachev and coworkers [22]. As the width of transmission line is directly related to the dispersion near the EIT resonance, it is also a key issue in dispersive measurements.In a three-level Λ-type system if the system is homogeneously broadened, as is well known, EIT can be achieved when the intensity of the driving field (Ω 2 ) is larger than the product of the decay rate of the coherence between the lower levels (γ bc ) and the homogeneous linewidth (γ). Then, if the system is inhomogeneously broadened (say, with the width W D ), one might guess that EIT can be achieved when Ω 2 is larger than γ bc W D instead of γ bc γ. This is not so. We show that one can still have EIT when Ω 2 ≫ γ bc γ even in the case of inhomogeneous broadening.For the spectral width of EIT, if the system is homogeneously broadened, the two absorption lines are separated approximately by the Rabi frequency of the driving field Ω when Ω is larger than the homogeneous linewidth γ. When Ω ≪ γ, it becomes Ω 2 /γ. Then, if the system is inhomogeneously broadened, it might be inferred that the EIT width goes as Ω when Ω is larger than the inhomogeneous linewidth W D , and becomesIn the literature, however, we find that the narrow feature superimposed on the Doppler broadened p...

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Using atomic force microscopic and tribometry techniques, we characterized the cuticle surface of the American cockroach (Periplaneta americana) and studied lubrication properties of the wax developed to protect the cuticle. Experimental results showed that the roach cuticle had the ability to self-clean and that there were dimples on its surface to naturally disperse wax. It was observed by changes in friction that a thicker layer of wax was formed at the ventral abdomen, where dimples were present, than at the dorsal abdomen, which had no major features. The wax was found to have similar lubrication properties as commercial automobile oil, but with the ability to form thin films and repel dust. The dust repelling qualities make it a potential candidate for the lubrication of microelectromechanical system and nanoelectromechanical system devices that require supercleaning surfaces that is cost effective.

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