Mark J. Rosker

Salt-based approach for frequency conversion materials

A salt-based approach for the development of frequency conversion materials is presented. Salts are generally rugged materials due to their strong ionic bonding. A high degree of chemical substitution (both of anion and cation) is possible, including highly nonlinear organic ions. This flexibility is consistent with the use of empirical survey techniques to identify promising candidate materials. We describe in detail our experimental approach and present examples of nonlinear optical crystals we have identified in our materials surveys.

Picosecond pulsed diode ring-laser gyroscope.

We have demonstrated a novel solid-state ring-laser gyroscope, which utilizes as the gain media a pair of semiconductor diodes in an external ring cavity. The use of homogeneously broadened gain media is made possible by actively mode locking the laser. We observe no evidence of frequency locking between the counterpropagating optical pulse trains generated in the cavity to within the limit of our experimental resolution.

Time‐resolved degenerate four‐wave mixing studies of solid‐state poly(p‐phenylene) oligomers

We have measured χ(3) for a series of solid‐state samples of polyphenylene oligomers, (Ph)n, where n=4–8 is the number of phenyl ring units, using optical pulses of 140 fs duration and 650 nm wavelength. A degenerate four‐wave mixing (DFWM) signal was only observable for n≥6, and thereafter the measured values of χ(3) increased monotonically with n. Measurements of the linear absorption are also reported. Although the DFWM measurements were performed at wavelengths far from resonance, the figure of merit χ(3)/α was essentially flat beyond n≥6. In contrast to previous studies of oligomers in solution, the principal nonlinear responses were instantaneous within the 140 fs temporal resolution.

Pulsed diode ring laser gyroscope

We have demonstrated a novel solid-state ring laser gyroscope by actively modelocking a pair of InGaAsP diodes in an external ring cavity. We observe no evidence of gain competition or frequency locking between the counterpropagating optical pulse trains circulating in the cavity to within the limit of our experimental resolution.

Frequency locking in phase-conjugate ring oscillators

Frequency locking in a photorefractive phase-conjugate ring oscillator was studied by injecting a seed beam into the resonator. For a seed beam coherent with the pump, frequency locking of the oscillator was observed at large seed powers. At lower seed levels, the beat signal displayed multiple harmonics in its frequency behavior. No evidence of locking was found for a seed incoherent with respect to the pump.

CeGeCl/sub 3/: A ferroelectric material with -0.4-20 /spl mu/m transparency for NLO applications

Oxides such as LiNbO3 and KDP are the most familiar nonlinear optical materials since they are readily available and bave Tiner desirable properties, such as reasonable nonlinear coefficients and high laser-da mage thresholds.

Picosecond-pulsed diode ring laser gyroscope

An external ring cavity containing as its active medium a pair of InGaAsP diodes is modelocked to produce picosecond pulses. In such a laser, a small frequency difference proportional to the nonreciprocal phase shift (resulting from, e.g., the Sagnac effect) can be observed by beating together the counterpropagating laser arms; the device therefore acts as a rotation sensor. In contrast to a conventional (cw) ring laser gyroscope, the pulsed gyroscope can avoid gain competition, thereby enabling the use of homogeneously broadened gain media like semiconductor diodes. Temporal separation of the pulses within the cavity also discriminates against frequency locking of the lasers. The picosecond pulsed diode ring laser gyroscope is reviewed. Both active and passive modelocking are discussed.