High-sensitivity frequency domain filtering baffle plate Z-scan method for measuring material nonlinearity

Abstract

The invention discloses a high-sensitivity frequency domain filtering baffle plate Z-scan method for measuring the material nonlinearity, and belongs to the fields of nonlinear photonic material and nonlinear optical information processing. The method of the invention comprises: the focus of a lens forms an image through another lens, and a filtering pinhole is arranged at the point of the image; and a circular diaphragm forms an image through a lens set formed by the above two lenses, and a coaxial circular baffle plate is arranged in the image plane. During the action of pulse laser, a sample moves from side to side near the focus of the lens. Through measuring the non-linear transmittance of an opening, the baffle plate, and the filtering pinhole, the non-linear absorption coefficient and the non-linear refraction coefficient of the material can be determined. The method of the invention is characterized by simple work measurement system optical path, obvious stray light influence filtering effect, high measuring sensitivity, and simple data processing, and can measure non-linear absorption and non-linear refraction at the same time.

Description

technical field [0001] The invention relates to a method for measuring optical nonlinearity of materials, which belongs to the field of nonlinear photonic materials and nonlinear optical information processing. Background technique [0002] With the rapid development of technologies in the fields of optical communication and optical information processing, the research on nonlinear optical materials is becoming increasingly important. The realization of functions such as optical logic, optical memory, optical transistor, optical switch and phase complex conjugation mainly depends on the research progress of nonlinear optical materials. There are many methods for measuring optical nonlinearity of materials, such as nonlinear interferometry, degenerate four-wave mixing, near-degenerate three-wave mixing, ellipsometry, beam distortion method, etc. Among them, the Z-scan method (Mansoor Sheik-Bahae, Ali A.Said, Tai-Hui Wei, David J.Hagan, E.W.Van Stryland. "Sensitive measuremen...

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Problems solved by technology

Flat-top beam Z-scan (zhao w.Palffy-Muhoray P., "z-scan technique using top hat beams", Appl Phys lett, 63:1613-1615 (1993)), which increases the sensitivity of z-scan measurement by 2.5 times, Japan Eclipse Z-scan (T.Xia, D.J.Hagan, M.sheik-Bahae, and E.W.Van Stryland, "eclipsing z-sdan measurement of λ / 10 -4 wave-front distortion, Optics letters, 19: 317-319 (1994)) replaces the far-field pinhole of the ordinary Z-scanning device with a disc, and uses a lens behind it to collect the edge beam into the detector, which can measure about λ / 10 -4 However, due to the weak light intensity at the edge, the edge noise reduces the measurement signal-to-noise ratio, thus limiting the further improvement of sensitivity

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