## Research Journal

### June 16th, 2006

This was my first week working here at the laser teaching center with Professor Noe and Professor Metcalf. Karen, Stephanie, and I are the three undergrads that are working in this lab. Maaneli is also in our group, but he has his own project with Professor Metcalf. On Tuesday Dr. Noe took us all outside and showed us a few examples of optical phenomena. We burned paper with a magnifying glass by finding its focal point and we looked at linear polarizers to name a few. Later in the week we started learning how to program in linux which allowed me to make this journal. We also had two lectures on laser cooling given by Professor Metcalf. The idea is to use multiple lasers to create an optical molasses that slows down atoms that enter it. It slows them down so much so that they get extremely cold to the order of 10's of microkelvin which is really interesting. Dr. Metcalf had told us that before laser cooling the coolest tempertures reached were on the order of millikelvin.

### June 23rd, 2006

This week we continued getting lectured on laser cooling by Professor Metcalf.

### June 30th, 2006

This past week the high school students, Matt, Hamsa, Scott, and Victor, started working here at the laser center. They will be here until August 11th. After getting to know them and finding out their interests, Steph, Karen and I each gave a lecture on topics related to optics. On Tuesday, Steph gave a spectacular lecture on complex numbers. The high schoolers really enjoyed it and took especial interest in the magic of euler's formula. On Wednesday, Karen gave her own dazzling powerpoint lecture on geometric optics which included multiple derivations of both the law of reflection and snell's law. She also discussed elliptical, parabolic, and spherical mirrors and did a great job despite my computer running out of bateries in the middle of it. On Thursday, I gave my lecture on interference and diffraction, I first discussed plane and spherical waves which led into interference via Young's two slit experiment. I showed them the usefullness of complex numbers in deriving the intensity pattern on a screen from Young's experiment. Then I went into multiple slit interfence which led to describing diffraction as interfence from an infinite number of slits in a finite distance. This is Huygens diffraction principle described as interfence from an infinite number of point sources.

### July 7th, 2006

This was a short week because of the 4th of July. On Thursday, I decided to pursue a research project in photorefractive nonlinear optics. The photorefractive effect is the fluctuation of the index of refraction of a nonlinear material in response to an applied laser light intensity that is spatially modulated. Applications of photorefractive materials can be found in image processing, optical computing, and optical data storage which is what, in particular, I am interested in. I want to develop some type of experiment to discover some of the different properties of photorefractive materials and possibly use this to store some form of information as a hologram. I am reading a paper on the subject and Dr. Noe is going to contact an expert in the field to possibly help me develop an experiment.

### July 14th, 2006

This week I started coming up with ideas for a specific project dealing with the photorefractive effect. I think I found a possible project that is interesting and hopefully feasable. My plan is to create a phase conjugate wave using a photorefractive crystal and three input waves. There is a reference wave and an object wave that are incident on one side of the crystal. The reference and object both come from the same laser sourse, but the object has passed through the object that is going to be imaged which is how a normal hologram is developed. The third input wave is the reading wave which is incident on the other side of the crystal, travels in the exact opposite direction of the reference wave, and originates from the same original laser source. These three waves combine and are coupled in such a way so that the output wave is in the exact opposite direction of the object wave. It is the phase conjugate wave. I am not totally sure what I am going to use the wave for. Possibly for image cleaning or instantaneous holography. Hopefully next week I can start actually setting up the experiment because I still need to find a photorefractive crystal because we do not have one here in the lab.

### July 21st, 2006

This week I began setting up my project. I still do not have a photorefractive crystal, but that will change soon because luckily Marty has a contact at Crystal Technologies who is going to send us a crystal. It should get here early next week. In the mean time, I have started setting everything up around where the crystal will go. I'm using a random polarized helium neon laser as my source. Since I need polarized light incident on the crystal, I need to put a rotating polarizing crystal just after the laser. Unfortunately this cuts the laser intensity by a little more than half. I measured, with a photodetector, the original laser to be 16mw and the polarized light to be 7.2mw. Then I put a beam splitter in that transmits about 50% of the light and reflects about 50% in a different direction. One of these beams will go directly to the crystal and the other will be reflected off another mirror before reaching the crystal. After the beams hit the crystal they will each continue on to a photodetector. I will then measure the intensity of each beam both with the crystal and without. I am not sure exactly what I am going to do from there. Also this week, I taught Hamsa, Victor, and Scott about matrices and there applications to geometrical optics and ray tracing.

 Mike Kornhausermkornhau (a) rochester.edu Home  Laser Teaching Center Calender