Tunable laser light source

Abstract

Abstract : A laser diode and a fiber Bragg grating can be used to construct a tunable laser light source. This new tunable laser has a central wavelength of 682.6 nm (red light) and a bandwidth less than one twentieth of one nanometer. It is tunable over a range greater than five nanometers. Tunable light sources have applications in fundamental research such as noise studies in optical amplifiers and high precision spectroscopy, as well as applications in optical engineering, including communications and LIDAR systems. Although tunable lasers exist for these purposes now, this new tunable laser has an unique construction. It contains a laser diode, which is a semiconductor pn junction diode that emits coherent light once a sufficient drive current is supplied, and an in-fiber Bragg grating that is used to modify the output of the laser diode. The grating provides additional feedback to the laser diode at the wavelength of the grating's Bragg condition. The combined system lasers at this wavelength. Tuning is accomplished by straining the grating within its fiber and thus changing the wavelength of its Bragg condition. This strain is evolved by embedding the grating in a composite beam and deflecting the beam.