Nonlinear Nanowire Close to a Truncated Metallic Film: a Step Toward Nanosized Light Sources
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Nonlinear Nanowire Close to a Truncated Metallic Film: a Step Toward Nanosized Light Sources Nafiseh Zavareian & Reza Massudi
Received: 26 April 2012 / Accepted: 5 November 2012 / Published online: 19 December 2012 # Springer Science+Business Media New York 2012
Abstract A controllable nanosized light source based on nonlinear interaction of light and a semiconductor nanowire is proposed. Surface plasmon polariton (SPP) waves with different frequencies propagate along the upper and lower surfaces of a truncated metallic film and are scattered at its end face. A nanowire, in that vicinity, is pumped by the scattered light, and new harmonics are generated via second-order nonlinear optical effects. Green's function surface integral equation method is exploited to numerically calculate the electric field, the magnetic field, and the power of the generated frequency components. Results show that the power of the generated harmonics depends on the position and radius of the nanowire, thickness of the metallic film, as well as the wavelength of the incident SPP waves. On the other hand, by controlling the phase difference between incident SPP waves having the same frequencies, it is possible to manipulate the electric field pattern and also to change the power of the generated harmonics. Keywords Surface plasmon polariton . Green's function surface integral equation method . Nonlinear nanowire . Second-order nonlinearity
Introduction In recent years, semiconductor nanowires with subwavelength dimensions have attracted great interest due to their unique optical and electrical properties which are important in scientific researches and technological applications [1–10]. In particular, their nonlinear optical properties, N. Zavareian : R. Massudi (*) Laser and Plasma Research Institute, Shahid Beheshti University, Evin, GC, Tehran, Iran 19839 e-mail: [email protected]
especially second-order nonlinearity, suggest them as an efficient frequency converter [11–15] and, consequently, as a nanosized light source to generate harmonic frequencies. These nanosized sources can be used to detect single chemical or biological molecules. Different techniques have been proposed for pumping nonlinear semiconductor nanowires. In most of them, a beam is focused on the nanowire to generate second-order harmonics [11–15]. Although those techniques are simple, it is impossible to focus light in subwavelength scale in order to excite a single nanowire. One solution to overcome the diffraction limit of the light is to use a highly localized electromagnetic field generated by near-field techniques such as that generated in scanning near-field optical microscopy (NSOM) [16]. But, such system is not easily available. Furthermore, nonlinear processes require an intense incident beam, and hence, using NSOM in illumination mode is not preferred. Moreover, to use NSOM in other modes, a strongly confined optical field should be generated by focusing the beam of a laser on the apex of NSOM. But, since a second-order nonlinear process can occur not o
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