Research

In addition to teaching, the Faculty in the Department of Physics are actively engaged in the search for new knowledge and novel applications of physics. Researchers in the Department work in topics ranging from the very small (quantum systems) to the very large (space weather, astrophysics, and cosmology), from the highly theoretical (geometric algebra, many-body physics) to the very practical (photonics, vacuum physics technology, and instrumentation), and from pure hardcore physics (condensed matter physics, general relativity, and mathematical physics) to highly interdisciplinary topics (atmospheric physics, climate physics, and materials science). Listed below are the research groups in the Department:

Earth System Physics:
     •  Air Quality Group
               •  Cambaliza,  Simpas
     •  Physics of the Climate and Weather Group
               •   Narisma, Olaguera, Villarin
     •  Geophysics Group
               •  Maquiling
     •  Space Weather Group
               •  Bennett, McNamara, Sugon

Materials Science:
     •  Auxetic Materials Group
               •  Chan
     •  Materials Characterization Group
               •  Chan
     •  Thin Films and Plasma Processing Group
               •  Culaba, Delos Santos, Mahinay

Photonics:
     •  Photonics Group
               •  Guerrero, 

Physics Education:
     •  Physics Education Group
               •  Cambaliza, Chan, Culaba, Dailisan, Maquiling

Theoretical and Computational Physics:
     •  Geometric Algebra Group
               •  McNamara, Sugon
  
 
Some Selected Publications:

2015

Skew ray tracing in a step-index optical fiber using geometric algebra

By Sugon, Quirino Jr., McNamara, Daniel J., SJ

We used geometric algebra to compute the paths of skew rays in a cylindrical, step-index multimode optical fiber. To do this, we used the vector addition form for the law of propagation, the exponential of an imaginary vector form for the law of refraction, and the juxtaposed vector product form for the law of reflection. In particular, the exponential forms of the vector rotations enables us to take advantage of the addition or subtraction of exponential arguments of two rotated vectors in the derivation of the ray tracing invariants in cylindrical and spherical coordinates. We showed that the light rays inside the optical fiber trace a polygonal helical path characterized by three invariants that relate successive reflections inside the fiber: the ray path distance, the difference in axial distances, and the difference in the azimuthal angles. We also rederived the known generalized formula for the numerical aperture for skew rays, which simplifies to the standard form for meridional rays.

2012

Ray transfer matrix perturbation for an optical component with aberration

By

Jerry T. Barretto, Clark Kendrick C. Go, and Stein Alec C. Baluyot, "Ray transfer matrix perturbation for an optical component with aberration," Chin. Opt. Lett. 10, 080801- (2012)

The perturbation theory of matrices is applied to ray transfer matrices (RTMs) to describe an optical component with aberration. A quantitative description of the perturbation extent corresponding to aberration strength is provided using condition numbers and absolute errors for the perturbed RTM. An application to a single small aberration is presented, and the results are compared with those of the diffraction theory of aberrations.

OCIS codes: 080.0080, 080.2720, 080.2730.
doi: 10.3788/COL201210.080801.

Polarization ellipse and Stokes parameters in geometric algebra

By Sugon, Quirino Jr., McNamara, Daniel J., SJ

Adler G. Santos, Quirino M. Sugon, Jr., and Daniel J. McNamara, "Polarization ellipse and Stokes parameters in geometric algebra," J. Opt. Soc. Am. A 29, 89-98 (2012).

In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell’s equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation. © 2012 Optical Society of America

2011

Modeling local climate extremes in central Philippines

By Narisma, Gemma Teresa T.

Faye Abigail T. Cruz1*, Gemma Teresa T. Narisma1, 2 and Julie Mae B. Dado1, “Modeling local climate extremes in central Philippines,” SPP 2011-172 Abstract The climate extremes of selected areas in central Philippines are simulated using a regional climate model. Model results are validated with observed data from station and gridded reanalyses using different metrics. While the observed seasonal variability in mean temperature and rainfall are reproduced in the model, magnitudes are slightly underestimated. Probability density functions indicate the model’s tendency to overestimate temperature extremes. Recent trends in the extremes indices show fewer hot days and fewer cool nights at the selected sites.

(poster, national conference)

Reflectance measurements and optical simulation of spectral filters in Philippine beetle

By Guerrero, Raphael A.

Erika B. Aranas* and Raphael A. Guerrero, “Reflectance measurements and optical simulation of spectral filters in Philippine beetle,” SPP 2011-013.

Interesting photonic assemblies in nature are continuously discovered and characterized because of their ingenuity and sophistication which often inspire biomimicry. The natural optical filter found in a Philippine beetle is characterized via reflectance experiments and modeled as a multilayer stack of air and chitin planes. Geometric parameters are predicted via Bloch’s theorem, and reflected spectra are simulated using ray transfer matrices. Results are consistent with the observed iridescent behavior of the insect.

(poster, national conference)

Fluidic actuation of a binary optical element

By Guerrero, Raphael A.

Johanna Mae M. Indias1*, Sarah Jaye C. Oliva2 and Raphael A. Guerrero3, “Fluidic actuation of a binary optical element,” SPP 2011-052.

Characterization of a fluid-controlled elastomeric grating is presented. Using a HeNe laser beam (λ = 632.8nm), changes in diffraction angle and beam profile are measured and observed as gradual volumetric increments of water are introduced into a fluidic chamber. A diffraction angle range of 17 degrees was achieved with the addition of 1.0 mL of water.

(poster, national conference)

Impact of Problem-Based Learning (PBL) on Student Achievement in Secondary Physics Course

By

M.L. Bergantin and J.T. Barretto, “Impact of Problem-Based Learning (PBL) on Student Achievement in Secondary Physics Course”

This paper examines the effectiveness of problem based learning in developing the problem solving skills of students. A pre-test post test control group was adopted for the study. Statistical tests on two hypotheses involving problem solving skills developed using traditional and PBL-based instruction were performed. Results showed that there is no significant difference on the problem solving skills developed using PBL and traditional methods. © 2011 Samahang Pisika ng Pilipinas

(poster, national conference)

An alternative approach for quantifying climate regulation by ecosystems

By Narisma, Gemma Teresa T.

Paul C West, Gemma T Narisma, Carol C Barford, Christopher J Kucharik, and Jonathan A Foley. 2011. An alternative approach for quantifying climate regulation by ecosystems. Frontiers in Ecology and the Environment 9: 126–133. doi:10.1890/090015 Concepts and Questions An alternative approach for quantifying climate regulation by ecosystems Paul C West1,2*, Gemma T Narisma1,3, Carol C Barford1, Christopher J Kucharik1,4, and Jonathan A Foley5

Ecosystems provide multiple benefits to people, including climate regulation. Previous efforts to quantify this ecosystem service have been either largely conceptual or based on complex atmospheric models. Here, we review previous research on this topic and propose a new and simple analytical approach for estimating the physical regulation of climate by ecosystems. The proposed metric estimates how land-cover change affects the loading of heat and moisture into the atmosphere, while also accounting for the relative contribution of wind-transported heat and moisture. Although feedback dynamics between land, atmosphere, and oceans are not modeled, the metric compares well with previous studies for several regions. We find that ecosystems have the strongest influence on surface climatic conditions in the boreal and tropical regions, where temperature and moisture changes could substantially offset or magnify greenhouse-forced changes. This approach can be extended to estimate the effects of changing land cover on local, physical climate processes that are relevant to society.

1Center for Sustainability and the Global Environment (SAGE), University of Wisconsin-Madison, Madison, WI; current address: Institute on the Environment, University of Minnesota, St Paul, MN

2The Nature Conservancy, Madison, WI

3Ateneo de Manila University, Loyola Heights, Quezon City, Philippines

4Department of Agronomy, University of Wisconsin-Madison, Madison, WI

5Institute on the Environment, University of Minnesota, St Paul, MN