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J. M. Ward

Publications and source records attributed to J. M. Ward.

3 recordsLinked to original sources

Optical Micro- and Nanofiber Pulling Rig

We review the method of producing adiabatic optical micro- and nanofibers using a hydrogen/oxygen flame brushing technique. The flame is scanned along the fiber, which is being simultaneously stretched by two translation stages. The tapered fiber fabrication is reproducible and yields highly adiabatic tapers with either exponential or linear profiles. Details regarding the setup of the flame brushing rig and the various parameters used are presented. Information available from the literature is compiled and further details that are necessary to have a functioning pulling rig are included. This should enable the reader to fabricate various taper profiles, while achieving adiabatic transmission of ~ 99% for fundamental mode propagation. Using this rig, transmissions ranging from 85-95% for higher order modes in an optical nanofiber have been obtained.

physics.optics

Trapping of a microsphere pendulum resonator in an optical potential

We propose a method to spatially confine or corral the movements of a micropendulum via the optical forces produced by two simultaneously excited optical modes of a photonic molecule comprising two microspherical cavities. We discuss how the cavity enhanced optical force generated in the photonic molecule can create an optomechanical potential of about 10 eV deep and 30 pm wide, which can be used to trap the pendulum at any given equilibrium position by a simple choice of laser frequencies. This result presents opportunities for very precise all-optical self-alignment of microsystems.

physics.optics

Optical bistability in Er-Yb co-doped phosphate glass microspheres at room temperature

We experimentally demonstrate optical bistability in Er3+-Yb3+ phosphate glass microspheres at 295 K. Bistability is associated with both Er3+ fluorescence and lasing behavior, and chromatic switching. The chromatic switching results from an intrinsic mechanism exploiting the thermal coupling of closely-spaced energy levels, and occurs simultaneously with the intensity switching. A contrast ratio of 3.2 has been obtained for chromatic switching, and the intensity switching shows ratios of 2.4 for 550 nm and, 1.8 for the 660 nm fluorescence emissions, and 11 for the IR lasing at 1.5 um. Concurrent with these observations, we investigate a temperature dependent absorption of pump power which exhibits bistable behavior. The influences of the host matrix on lasing and fluorescence mechanisms are highlighted.

physics.optics