Recent advances in the field of phosphate glass fiber lasers are reviewed. Fabrication of microstructured fiber and
writing of fiber Bragg gratings in passive and active phosphate glass fiber are demonstrated. Based on these novel
components we fabricate cm-long, Watt-level fiber lasers that allow for tunable, single longitudinal mode operation.
Optical and electron confinement are utilized to tailor the optical characteristics of active materials and photonic devices. A technique to incorporate semiconductor quantum dots into planar glass waveguides with low propagation loss is demonstrated. The waveguides are fabricated by potassium-sodium and silver-sodium ion exchange processes in glasses that contain PbS quantum dots with radii of a few nanometers. The unique optical properties of the quantum dots are preserved throughout the waveguide fabrication process. We also demonstrate novel compact fiber lasers based on active, highly doped fibers with photonic crystal cladding. The flexibility provided by microstructuring the fiber enables improved fiber laser performance and several Watts of laser output are generated from few centimeters of active fiber.
A three element, 15.3 cm, fiber Bragg grating array (FBGA) operating at 1550 nm wavelength is fabricated using a single mode photosensitive fiber. The FBGA is initially simulated using in-house developed software based on the Transfer Matrix Method, then fabricated using a double frequency Argon laser and a phase mask technique, and interrogated using Optical Frequency Domain Reflectometry. A single fiber Bragg grating (FBG) is accurately strain calibrated using a Fabry-Perot interferometer and piezoelectric actuation. The piezoelectric is linearly ramped, and the shifts in the Bragg wavelength along with the fringe count from the Fabry-Perot interferometer are recorded. The fringe count is then used to determine the strain on the FBG and compared to changes in the Bragg wavelength in-order to calculate the strain gage factor. This result is used to calibrate the FBGA for strain measurements. The FBGA is then bonded to a cantilever beam with three electric strain gages attached next to each FBG in the array. The axial strain results obtained from the electric strain gages and FBGA are compared for various displacements of the cantilever beam. The Fabry-Perot interferometer and piezoelectric calibration method is a non-destructive process that eliminates the need to bond the FBG to an external support during the calibration process, and can also be used to calibrate electric strain gages.