Cascaded all-optical operations in a hybrid integrated 80-Gb/s logic circuit.

We demonstrate logic functionalities in a high-speed all-optical logic circuit based on differential Mach-Zehnder interferometers with semiconductor optical amplifiers as the nonlinear optical elements. The circuit, implemented by hybrid integration of the semiconductor optical amplifiers on a planar lightwave circuit platform fabricated in silica glass, can be flexibly configured to realize a variety of Boolean logic gates. We present both simulations and experimental demonstrations of cascaded all-optical operations for 80-Gb/s on-off keyed data.

Effects of mechanical stress on the transmission properties of optical fiber packaged in a composite structure.

Optical circuit boards for system-level interconnection may be fabricated by bonding segments of optical fiber, in the configuration necessary for signal distribution, to a substrate such as a printed wiring board. To measure the effects of mechanical stress on optical transmission, a four-point bend test is applied to prototype optical circuit boards. The results show that flexing a board to a strain of approximately 0.3% leads to a decrease in loss of 0.012 ± 0.002 dB for multimode fiber. Flexing of a thin board, in two directions, around 40-in.- (101.6-cm-) bend-radius mandrels decreases fiber loss by almost 1 dB after 700 cycles. Single-mode fiber bonded to aboard, however, exhibits an increase in loss of 0.11 ± 0.05 dB under an induced strain of 0.3%, a change that is not significant relative to typical loss-per-line budgets in real systems.

Kinetic differences at low temperatures between R and T state carbon monoxide-carp hemoglobin.

We use the low-temperature recombination kinetics of carbon monoxide with carp hemoglobin to determine that the R and T states of hemoglobin exhibit different low-temperature geminate recombination kinetics. The peak of the fitted Gaussian activation energy spectrum is at 1.5 kcal/mol for R state and 1.8 kcal/mol for T state. The distribution in activation energies is fit well by the Agmon-Hopfield linear strain model. The T state is fit with a stronger elastic constant than R, and has a larger displacement of the protein conformation coordinate than does the R state, indicating that the T state does have a significantly greater rigidity and also stores more strain energy in its conformational states than does R hemoglobin. The pre-exponential in the activation energy spectrum is only a factor of two greater in the R than the T state and the low-temperature activation energy spectrum does not correctly predict the difference in the on rates for R and T states at 300 degrees K, indicating that processes removed from the binding site are important in cooperativity.