A transversely excited atmospheric pressure nitrogen laser (TEA N2 Laser) is a molecular pulse gas laser, operated at atmospheric pressure, which generates an electromagnetic wave in ultraviolet wavelength of 337.1 nm. It can operate without an optical resonator. We present a TEA N2 laser setup excited by an electronic discharge circuit known as the Blumlein circuit. Our setup is composed of simple components commonly found in everyday life. The setup can be utilized in classroom to demonstrate the dependence of the laser intensity on the flow rate of nitrogen gas.
Carbon nanotubes (CNTs) were grown on Ni catalyst with Al catalyst supported layer prepared on silicon substrate at different temperatures by TCVD. TEM images clearly showed the multi-wall structure of carbon nanotubes (MWCNTs) and SEM images revealed that the average diameters of MWCNTs were 116, 121, 142 and 162 nm for the growing temperatures of 600, 700, 800 and 900°C, respectively. The increase of tube diameter was due to the difference of Ni particle size and distribution after pretreatment. Raman spectrum revealed the two peaks of the D and G band at 1282- 1290 and 1588-1598 cm-1, respectively. The tubes grown at 800°C showed a shoulder peak of G band at 1598 cm-1. The minimum of defect induced disorder (ID/IG) of 1.19 was found at 800°C whereas the maximum disorder of 1.70 was observed at 600°C. All results confirm that the tube growth at 800°C shows the minimum imperfective disorder and the tube diameter can be manipulated by the Ni particle size and distribution.
The optical bistability is a fundamental nonlinear feature of the ring resonator. A geometric and potential dynamics interpretation of the bistability is given. Accordingly, the bistability of the nonlinear system is shown to be a consequence of geometric laws of vector calculus describing the resonator ring. In contrast, the so-called transcendental relations that have been obtained in the literature in order to describe the optical wave are interpreted in terms of potential dynamical systems. The proposed novel interpretation provides new insights into the nature of the ring resonator optical bistability. The fundamental work by Rukhlenko, Premaratne and Agrawal (2010) as well as a more recent study by Chiangga, Pitakwongsaporn, Frank and Yupapin (2013) are considered.
We present results of numerical simulations of a supercontinuum generation (SCG) in a Ge11:5As24Se64:5 chalcogenide rectangular waveguide with air as an upper cladding and the lower cladding is magnesium fluoride. A broadband infrared 1.3-3.0 μm SCG could be achieved by pumping with femtosecond pulses in the two zero dispersion wavelengths. The effect of chirp on SCG spectrum has been also investigated. The simulation shows a significant SCG spectral flatness in the mid-infrared range with positive frequency chirp input pulses.
In this paper, we analyzed and investigated the nonlinear switching characteristics of an optical device using a double-coupler silicon ring resonator in the presence of the linear losses, the Kerr nonlinearity, two-photon absorption, thermo-optic effects, free-carrier-induced absorption, and dispersion. Results obtained have shown that the general features of the nonlinear switching of the throughput and drop port signals are similar to a single-couple ring and nonlinear Fabry-Perot resonators, respectively. The interesting results of the double-coupler silicon ring resonator are the low switching power conditions and the linear amplification gain. The various applications can be provided by controlling the input-output of silicon-based resonators, for instance, by controlling the coupling ratio, free-carrier lifetime, and input wavelength, in which the multiple applications for optical switches, logic gates, and memories can be provided.