Abstract:
PURPOSE: A method for generating a large area holographic grating and an apparatus thereof are provided, which fabricates a large area grating below an effective area of a lens as using an optical system of small caliber. CONSTITUTION: A light projected by an ultraviolet ray laser(10) of a single wavelength is focused to a pin hole(14) with an object lens(12) and then passes through a spatial lens removing noise in the air, and then the beam extended using a collimating lens(16) and passes through an inverse Gaussian transparent filter(22) and is irradiated to a sample(18) in parallel. The sample is located to have an angle to a path of the light, and a mirror(20) is attached to the sample so that a reflected light has a specific angle with the incident light to control an interval of an interference pattern.
Abstract:
PURPOSE: A wavelength transformation system for increasing an extinction ratio and a wavelength transformation bandwidth of an optical signal is provided to increase an extinction ratio and a wavelength transformation bandwidth of an optical signal by coupling a wavelength transformation process due to a four-wave mixing phenomenon of a semiconductor optical amplifier and a wavelength transformation process due to a four-wave mixing phenomenon of a distributed transaction fiber. CONSTITUTION: The first wavelength transformer(100) receives a DFB(Distributed FeedBack) semiconductor laser beam and a variable wavelength semiconductor laser beam and performs a wavelength transformation process due to a four-wave mixing phenomenon of a semiconductor optical amplifier. The second wavelength transformer(110) receives an output signal of the first wavelength transformer(100) and the variable wavelength semiconductor laser beam and performs a wavelength transformation process due to the four-wave mixing phenomenon of a distributed transaction fiber.
Abstract:
PURPOSE: A method for locally forming a different band gap in a quantum well by a dielectric-semiconductor composite cover layer is provided to regulate a degree of disorder of the quantum well. CONSTITUTION: The method begins with growing an InGaAs/InGaAsP quantum well substrate by a chemical beam epitaxy technique. Next, a dielectric thin layer made of such as SiO2 or SiNx is formed as a cover layer on the quantum well substrate by a plasma-enhanced chemical deposition technique. After a heat treatment step is carried out at a temperature of 600 - 800°C for 4 - 16 minutes, the dielectric thin layer is removed. In addition, InP, InGaAs or InGaAsP is used as a semiconductor cover layer.