Laser Graphic

Welcome to the Home Page of

Dr. John Varriano

Physics Department
Christian Brothers University

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Biographical Info


Professional Interests


Curriculum Vitae

My Courses


My Schedule


My Applet Collection

Physics at CBU


Plough Library


Degree Checklists

Please send comments or inquiries to: jvarrian@cbu.edu





Biographical Info

Professor of Physics (2005 - present)
Associate Professor of Physics (1997 - 2005)
Assistant Professor of Physics (1993 - 1997)
Christian Brothers University, Memphis, TN
Presently serving as Chair of Department of
Physics and Natural Science
CBU is located in the heart of midtown in Memphis, home of Elvis and birthplace of the blues.
Memphis is the best city for music and barbecue, both of which I enjoy tremendously.

Ph.D. in Optics (1993), The Institute of Optics, University of Rochester, Rochester, NY
The University of Rochester (U of R) is located just south of the city on the Gennessee River. The Institute of Optics is in the College of Engineering and Applied Sciences.

B.S. in Physics (1987), University of Pittsburgh, Pittsburgh, PA
The University of Pittsburgh (Pitt) is located on an urban campus in the neighborhood of Oakland in the city of Pittsburgh. The Department of Physics & Astronomy offers undergraduate (B.A., B.S.) and graduate (Master, Ph.D.) degrees.

Pittsburgh is located in the southwestern corner of Pennsylvania where the Allegheny and Monongahela Rivers meet to form the Ohio River.

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Professional Interests

Physics Education
I am very interested in different methods of physics instruction. If you have any comments in this area, please contact me at the address at the top of my page.

Here at CBU, I have students in the introductory physics courses perform computer assisted homework problems that were written by Dr. Johnny Holmes and myself. We have found the problems to be a tremendous tool in motivating and assisting the students.

Optics
My graduate research involved the growth, fabrication, and testing of semiconductor lasers. I continue to be interested in semiconductor optics, as well as other optical phenomena. I have developed and teach an introductory optics course for nonscience and natural science undergraduate students. If you have any suggestions for the course, write to me at the address at the top of my page.

Philosophy of Science
My continued teaching of physics, particularly quantum physics, has increased my interest in the philosophy that arises from the scientific theories that we presently use. In particular, the externalization of mathematics from the pure abstract to "real", physical models fascinates me. I also like discussing the issue of determinism vs. randomness that is at the crux of the debate in quantum mechanics today. Write to me at the address at the top of my page if you have any comments.

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My Courses

Physics 150 Physics 201 Physics 347 Physics 447 Physics 460
Physics 251 Physics 202 Physics 353 Physics 452 Physics 491/492
Physics 252 Nat Sci 122 Physics 415

Download computer problems for Physics 150,251,252 and Physics 201,202
Download programs.

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Fall Semester 2014

MON TUE WED THU FRI
8:00
8:30
Physics 251
AH 005
Physics 251
AH 005
Physics 251
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8:30
9:00
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9:30
Physics 251
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office Physics 251
AH 005
office Physics 251
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office office office office office
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office Physics 353
AH 122
office Physics 353
AH 122
office
11:30
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12:00
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12:30
1:00
meeting
1:00
1:30
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2:00
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Physics 251 Lab
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Physics 251 Lab
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Physics 251 Lab
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Physics 201 Lab
AH 008
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Checklists
Natural Science 2014-15
Natural Science (Biology Licensure)2014-15
Natural Science (Chemistry Licensure)2014-15
Natural Science (Biology&Chemistry Licensure)2014-15
Natural Science (Physics Licensure)2014-15
Natural Science (Physics&Math Licensure)2014-15
Physics2014-15
Engineering Physics2014-15

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Cover Photo

Laser Graphic (Photo by Glenn Kohnke.)

This cover photo shows a magnified view of the operation of a semiconductor quantum well laser. The laser was fabricated at the Institute of Optics at the University of Rochester as part of my graduate research in visible semiconductor lasers under the advisement of Dr. Gary Wicks.

The laser consists of a thin active layer (about 100 Angstroms) of Gallium Indium Phosphide sandwiched between several layers of Aluminum Gallium Indium Phosphide. The active layer is so thin (about 50 atomic layers) that the electrons and holes trapped in the layer behave as if they were inside a square, one-dimensional, quantum well. Hence, these devices are called quantum well lasers. The crystal structure was grown in a Molecular Beam Epitaxy (MBE) machine operated by Michael Koch. Once the material was grown, I fabricated individual, rectangular lasers by defining metal electrical contacts and cleaving out end mirrors.

The photo shows a top view of the laser. The laser is 0.03 millimeters wide and 0.3 millimeters long. Current is injected into the top by a metal probe. (The presence of the probe causes the break in the red line around the top edge of the laser in the photo.) Red light with a wavelength of 676 nanometers is being emitted out of the two ends of the laser. The striations in the output light are caused by the light reflecting off of scratches in the copper block on which the laser is sitting.

Semiconductor lasers are used extensively in optical communication and in optical storage devices such as CD and DVD players. This particular laser was the first visible quantum well laser grown in an MBE machine that utilized solid phosphorus as a source. Advances in material science have led to the development of shorter wavelength lasers such as in blue-ray players. The shorter wavelength allows the light to be focused to a smaller spot, enabling more information to be recorded on the disc.

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Background courtesy of me!