The construction and computational modeling of a fiber Bragg grating tunable laser diode

The widespread adoption of wavelength division multiplexing to increase the bandwidth of optical fiber communication systems has provided a major impetus for research on low cost, single-mode, wavelength stable tunable diode lasers for use in optical telecommunications due to the large volume of lasers required. Other applications, such as demodulation of fiber Bragg grating sensor systems can also make use of inexpensive tunable laser diodes. In addition, the steady increase in the amount of computational power available has led to the widespread use of computers to model physical systems both to predict system performance and to gain insight into physical behavior.; Following a brief review of the application and construction of optical fiber Bragg gratings and a discussion of diode lasers and common methods of tuning diode laser wavelengths, a coupled-cavity approach to modeling laser diode output spectra, the construction of a fiber Bragg grating wavelength tunable laser, and the coupled cavity model of the fiber Bragg grating wavelength tunable diode laser are detailed. The physical laser system consists of a commercial Fabry-Perot diode laser with a cavity length of 300 microns, antireflection coated with a single layer of SiO, and coupled into an optical fiber containing a fiber Bragg grating. Wavelength tuning is accomplished by applying axial strain to the fiber grating. The coupled cavity model directly includes the antireflection coating, includes the fiber Bragg grating as an index step, and is the first reported implementation of this method to model fiber Bragg grating coupled laser diodes. The measured output spectra of the physical laser diode system and the calculated output spectra are given and compared. Continuous tuning of the diode laser by applying axial strain to the fiber grating is not observed nor calculated to occur for a single-layer silicon monoxide antireflection coating. To achieve continuous wavelength tuning, better antireflection coatings will need to be developed.