Carol M. Ford

Guided-mode grating resonant filters for VCSEL applications

A brief summary of both VCSEL technology and guided-mode grating resonant filters (GMGRFs) is presented. We then discuss benefits and issues of integrating the two technologies, emphasizing control of wavelength, polarization, and laser cavity modes. We present a GMGRF design suitable for a 980 nm InGaAs VCSEL and show that a significant loss (-4%) in reflectivity results from the slight loss associated with the minimum mirror conductivity required to inject current through the mirror. Experimental data are presented at 850 mm for gratings designed for and fabricated on fused silica substrates and illustrate that GMGRFs are also very sensitive to other forms of loss such as scatter caused by roughness in the grating lines. We suggest a hybrid approach of a GMGRF on a reduced distributed Bragg reflector stack as a means to circumvent the high sensitivity to loss in the GMGRF.

Optical amplification at 1534 nm in erbium-doped zirconia waveguides

We have developed planar waveguides with net gain in erbium-doped zirconia. Ion-beam sputtering was used to deposit amorphous high-refractive-index zirconia films, which were fabricated into single-mode waveguides. By adjusting oxygen flow rates while sputtering, and annealing the films after deposition, waveguide losses were reduced to 0.45 dB/cm at 1534 nm. Erbium in the zirconia, added by co-sputtering, had a wide, 54-nm full-width at half maximum emission band centered at 1538 nm, which offers potential advantages for wideband amplification in wavelength division multiplexing systems. When pumped with 36 mW at 980 nm, a 6.5 cm long, 8.8 /spl times/ 10/sup 19/ cm/sup -3/ doped waveguide produced 2.95 dB of optical amplification at 1534 nm. This was enough to overcome the waveguide loss and produce a small amount of net gain. With a higher pump power, substantial net gain appeared to be possible. These results show that wide-bandwidth erbium-doped optical amplifiers should be possible in zirconia.

Cavity element for resonant micro optical gyroscope

There is a need for an environmentally rugged, inertial based attitude and navigation control system with performance in the 10 degree/hr range but with an ultimate performance goal of 1 degree/hr. This non-GPS based system must withstand accelerations in the 3000 G range with a wide spectrum of vibrations. Optical gyros have good performance to size ratio and are insensitive to vibrations, acceleration, and are capable of handling a large range of rates. Cost, however, has been a limitation to wide use of optical gyros. Previous attempts using waveguides as the cavity have been limited by the performance of the waveguide, modulators, couplers, and the injection laser. However, telecommunications and optical computing developments have driven performance of the major components needed for a waveguide gyro. These improvements make a waveguide based gyro feasible. Honeywell and the University of Minnesota have been making significant strides toward a feasible resonant micro optic gyro (RMOG). Uniquely crucial components have been developed. Experimental measurements, when coupled with theoretical analysis predicts that 1 degree/hour performance can be achieved. This paper reports the results of the work conducted to date.

Rare earth doped planar waveguides in Zirconia

Zirconia (ZrO2) thin dielectric optical films demonstrate excellent transmission characteristics in the infrared for wavelengths [1] in the 1-5µm range important for optical communications.