Ross Schermer

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.

Synthesis of optical directional coupler modulators with linear response

The variable coupling directional coupler modulator is of interest for analog RF/microwave links because it can be synthesized to give linear electrical to optical conversion. The synthesis methods are still relatively undeveloped, however. This paper introduces an improvement to the preferred synthesis technique, the iterative Newtons method, which allows a closer match to the desired modulator response. A variable coupling directional coupler modulator synthesized with this improved method is then introduced, which has a response substantially more linear than previously reported.

Linearized electro-optic directional coupler modulator in stoichiometric lithium niobate

This paper reports on a novel optical linearized directional coupler modulator in stoichiometric lithium niobate (SLN). The linearized design has important applications in analog and RF communications systems where fiber optic link performance depends critically on the spurious-free dynamic range of the modulator. Newly available SLN has several distinct advantages over the congruently grown crystals commonly used for high speed integrated optic devices, including higher electrooptic coefficient and better ferroelectric properties. The higher electrooptic coefficient yields lower drive voltage, while the enhanced ferroelectric properties enable better velocity-matched electrode structures using domain inverted waveguides. This paper addresses the operation of the linearized directional coupler design, and the critical advantages of the SLN substrate for implementing high-speed operation using velocity-matching.

Graphical design of directional coupler devices

A graphical method of solving the first-order coupled mode equations is discussed and demonstrated, which provides a simple, intuitive approach to designing optical devices based on the directional coupler.