Cascading nonlinearities in an organic single crystal core fiber: The Cerenkov regime

The large nonlinear phase shifts imparted to the fundamental beam during Cerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to nonlinear phase shifts produced by the second order nonlinear coupling of the guided fundamental mode and the component of the Cerenkov second harmonic field trapped in the fiber cladding

Measurement Of The Complex Nonlinear Refractive-Index Of Single-Crystal P-Toluene Sulfonate At 1064-Nm

Z-scan at 1064 nm was used with single, 35 ps pulses to measure the nonlinear refraction and absorption in single crystal PTS (p-toluene sulfonate). Detailed analysis of the Z-scan data based on DELTAn = n2I + n3I2 and DELTAalpha = alpha2I + alpha3I2 yielded n2 = 5(+/-1) X 10(-12) cm2/W, alpha2 = 100(+/-20) cm/GW, n3 = 5(+/-1)X 10(-21) cm4/W2 and alpha3 = - 5 (+/- 1) cm3/GW.2 The resulting two photon figure of merit T for PTS is marginal for high throughput, all-optical waveguide switching at 1064 nm

Assessment Of Single-Crystal P-Toluene Sulfonate As An All-Optical Switching Material At 1.3-Mu-M

We evaluate the potential of single crystal PTS (p-toluene sulfonate) for all-optical applications at the 1.32 mum communications wavelength by measuring the electronic and thermo-optic nonlinearities, and the multiphoton absorption with picosecond pulses. With appropriate heat sinking, duty cycles greater than 25% should be possible without significant cumulative thermal effects for 1 W operating powers

Models of classroom assessment for course-based research experiences

Course-based research pedagogy involves positioning students as contributors to authentic research projects as part of an engaging educational experience that promotes their learning and persistence in science. To develop a model for assessing and grading students engaged in this type of learning experience, the assessment aims and practices of a community of experienced course-based research instructors were collected and analyzed. This approach defines four aims of course-based research assessment—(1) Assessing Laboratory Work and Scientific Thinking; (2) Evaluating Mastery of Concepts, Quantitative Thinking and Skills; (3) Appraising Forms of Scientific Communication; and (4) Metacognition of Learning—along with a set of practices for each aim. These aims and practices of assessment were then integrated with previously developed models of course-based research instruction to reveal an assessment program in which instructors provide extensive feedback to support productive student engagement in research while grading those aspects of research that are necessary for the student to succeed. Assessment conducted in this way delicately balances the need to facilitate students’ ongoing research with the requirement of a final grade without undercutting the important aims of a CRE education

Nonlinear Materials For Information Processing And Communications

The current state-of-the-art of nonlinear optical materials suitable for ultrafast all-optical applications is discussed. This survey will include progress in the third-order nonlinear properties of semiconductors, polymers and glasses and examples of their applications to devices. Also discussed will be \u27cascading\u27, a second-order nonlinearity-based approach to all-optical effects

Measurement Of Chi(3)(-Omega3;Omega1,Omega1,-Omega2) Spectra For Poly[3-Tetradecylthiophene]

We demonstrate that the Maker fringe technique can be applied to third order frequency mixing experiments designed to measure the electronic χ(3)(- approximately ega 3; approximately ega1, approximately ega1,- approximately ega2) dispersion with approximately ega1 for a poly[3-tetradecylthiophene] thin film. Both the magnitude and the phase of the χ(3) were obtained. In the magnitude spectrum there was a strong three-photon resonance where the output frequency (approximately ega3=2 approximately ega1- approximately ega2) corresponds to the energy level of the first one photon state. We also found a peak which could be either a 2 approximately ega1 or a Δ approximately ega (= approximately ega1- approximately ega2) resonance. Since this method is considered to be more sensitive to two-photon resonances that third harmonic generation, it can be used as a powerful tool to probe two photon states in the case of thin film polymer samples

Observation Of Mutual Trapping And Dragging Of Two-Dimensional Spatial Solitary Waves In A Quadratic Medium

We report experimental evidence for trapping of two-dimensional (2 + 1) spatial solitary waves in a KTP crystal resulting from its second-order nonlinearity. In addition, dragging of the solitary beams is observed as a function of fundamental input intensity and of the relative phase difference between the fundamental and the second harmonic when beams at both frequencies are coherently launched. © 1995, Optical Society of America

Third Order Nonlinear Optical Spectroscopy And Two Photon States In Rigid-Rod Benzobisthiazole Polymers

Third-Harmonic-Generation has been used to probe the dispersion of the third-order optical susceptibility of two rigid-rod liquid crystal Benzobisthiazole polymers in thin film form. Fitting to a two excited state model gives information about the existence, location and transition moment of the two photon excited state

Two-Dimensional Solitons With Second-Order Nonlinearities

We investigate the propagation of intense Gaussian beams in materials with quadratic nonlinearity. Excitation of (2 + 1) solitons is numerically predicted at finite phase mismatch and in the presence of linear walk-off between the fundamental and second-harmonic waves. The numerical results are interpreted in terms of the conserved quantities of the wave evolution, and the appropriate conditions for the experimental observation of the solitons are discussed. © 1995, Optical Society of America

Cascading nonlinearities in an organic single crystal core fiber: the Čerenkov regime

The large nonlinear phase shifts imparted to the fundamental beam during Čerenkov second harmonic generation (SHG) in a DAN, 4-(N,N-dimethylamino)-3-acetamidonitrobenzene, single crystal core fiber are explained and modelled numerically. Cascading upconversion and downconversion processes leads to nonlinear phase shifts produced by the second order nonlinear coupling of the guided fundamental mode and the component of the Čerenkov second harmonic field trapped in the fiber cladding. © 1994