PhD Physics Dissertation Defense: Generation of Periodic Beams with a Volume Holographic Axicon by Alvie Asuncion


The Department of Physics of Ateneo de Manila University cordially invites you to a dissertation defense:

  • PhD Physics Candidate: Alvie Asuncion
  • Schedule and venue: May 4, 4 PM, F106

Dissertation panel

  • Dr. Raphael A. Guerrero (Physics), Dissertation Adviser
  • Dr. Paul Leonard Atchong C. Hilario (UPD), Dissertation Examiner
  • Dr. Marienette Vega (Physics), Dissertation Examiner
  • Dr. Mikaela Irene D. Fudolig (Physics), Dissertation Reader
  • Dr. Joel T. Maquiling (Physics), Dissertation Reader


Superimposed Bessel beams (SBBs), which exhibit periodic behavior along the propagation axis, have been found useful in optical micromanipulation, atom trapping, laser drilling and other applications. The oscillating core diameter of such beams gained attention due to a pre-defined longitudinal pattern, which can be modified by varying certain experimental parameters. In this study, photorefractive volume holography is employed to generate SBBs with tunable periodicity. This is performed by using an axicon-telescope (a-t) system to generate quasi-Bessel beams (QBBs) with different transverse profiles corresponding to different cone angles. The generated QBBs are recorded as a thick hologram in a LiNbO3 photorefractive crystal. Stored holograms were considered as equivalent to a volume holographic axicon that effectively transforms the profile of Gaussian readout beams into QBBs. Retrieved QBBs from the crystal are focused by the original axicon to produce SBBs. Results show that both the QBB profile and the SBB period can be tuned by simply varying the a-t distance d. SBB oscillation periods that range from 4.3 cm to 6.1 cm were obtained. The method presented in this study allows tunability of SBB period through a simple rearrangement of optical elements.

Ateneo Physics student Mariel Dee recounts her Junior Term Abroad experience in Lille Catholic University

by Quirino Sugon Jr.

Fabian Lorenzo Dayrit, Tiffany Kang, Joyce Villanueva, and Mariel Dee before the Eiffel Tower in France

Fabian Lorenzo Dayrit, Tiffany Kang, Joyce Villanueva, and Mariel Dee before the Eiffel Tower in France

Mariel Alexis S. Dee, 4 BS Applied Physics with Applied Computer Systems, went to Lille Catholic University for her Junior Term Abroad (JTA) last August 26 to December 14, 2010. Mariel went with three Computer Science students:  Tiffany Kang, Joyce Villanueva, and Fabian Lorenzo Dayrit.  Below is an interview with Mariel by the Ateneo Physics News.

1. Why did you choose Physics?

I really intended to go to Psychology.  That is what I placed in my forms when I applied to other colleges. Then I asked myself: Should I really go to Psychology? Physics seems to be really cool. I thought that if I learn physics, I would also be cool.

2. Did you enjoy your first year in Physics?

Physics was really hard. I thought about shifting. But I do not want to be a quitter. I want to be a conqueror. Physics is fun–sometimes. Sometimes, I see the light.

3. What are your favorite subjects?

Ps 108 (Modern Physics) and Ps 43 (Electromagnetics and Relativity).

4. What research do you do in the Photonics Laboratory?

The thesis topic Dr. Raphael Guerrero gave me is measurement of microscopic deformation using double exposure volume holographic interferometry. There is the object beam and the reference beam. The object beam passes through an Sylgard elastomer. We leave it for a while until we make our first hologram. The Sylgard is then stretched and deformed. The object beam will have a phase difference than the original beam. A second hologram is recorded on the same spot of the photorefractive crystal. So even if you block the object beam, it is as if there is still the object as long as there is the reference beam. Then we take the hologram recorded so that we can analyze the deformation.

5. When did you go for your Junior Term Abroad (JTA)?

Last year, August 26 to December 14, 2010. I went with three Computer Science majors: Tiffany Kang, Joyce Villanueva, and Fabian Lorenzo Dayrit. My parents funded my travel.

We traveled a lot. We went to France, Italy, Germany, Switzerland, Belgium, and Netherlands. We traveled whenever we have a vacation. That was during the mid semester week or something.

Mariel Dee the computer geek

Mariel Dee the computer geek

6. What did you do in your classes?

We were taking computer subjects and Linux. We had to get Linux. We learned how to do Linux commands and made a website using Python or Django. We have a class on the C language and virtual LANs (Local Area Networks). I have four or five classes, which should have been part of some of my 5th physics year subjects.

7. Did you have culture shock?

We studied in Lille Catholic University. Actually, it is ISEN, which is the engineering school of the Lille Catholic university. In our first day in Lille, we were afraid. We do not know what to eat. We thought there would be no rice. But there was rice. We usually cook our own food because it is cheaper. We live in dorms. In Europe, the ground floor is the ground floor not the first floor. When you go up to the second floor, it is the first floor. When two of my friends in the dorm were assigned rooms in the fourth floor, we initially thought we were lucky because it is not the fifth floor. We carried our luggages up to the fourth floor. We then realized that the rooms are actually in the fifth floor.

In ISEN, we were the only international students. People are mostly afraid to talk to us. But we met a lot of nice people in the dorm. There are also other international students in the dorm. I met someone from Hungary. Her name is Kati Schmidt. She really became my friend even until now . We send mails to each other using Facebook.

Mariel Dee with the pigeons in Rome

Mariel Dee with the pigeons in Rome

8. Do you remember seeing a cross or a church in Lille?

I never noticed the cross in the classrooms.  I am a nominal Catholic.  I was baptized Catholic but do not go to mass anymore.  Maybe my last mass was in St. Paul’s College in High School.  There was a church there in Lille.  I do not know what it is called. It is not like the Church of St. Agustin nor the Church of the Gesu. It’s a different old European church.

9. What was your most memorable experience?

What I enjoyed the most was meeting different people. Your life there is different. You have different experiences. Dfferent people. You have to travel. You get to learn new things. Here I don’t cook. But there I learned to cook and be independent. We cooked sinigang but without kangkong. We cooked carbonara. We searched the recipe in the Internet or I asked my mom. We cooked adobo. There’s a supermarket where you can buy all the ingredients even those from the Philippines.

10. What is your favorite French cuisine?

I enjoyed the bread, especially the pain au chocolat. I enjoyed hearing it pronounced in French. The milk is also very delicious. When I went home, we tried all brands of milk in the supermarket . But I can not find any milk that tastes as good as that in France.

11. What was your worst experience?

Nothing much. But there were a lot of rallies. The French government planned to move the retirement age of from 60 to 62. So the people rallied. But it is far from our place.

French breakfast

French breakfast

12. Would you recommend the Junior Term Abroad (JTA) program to Physics majors?

It was a difficult year before the JTA. I have class by myself. I have nobody to relate to. When I got back, I have classmates. But I have to catch up for my physics subjects. It was really hard. But I would like to thank the physics department for giving me this experience. Even though the department had to open a new class just for me, the department still allowed me to do it.

But I would still recommend JTA, because it opens you to many new experiences. After the JTA, I feel like anything is possible. I can do anthing. Now I feel the world is not that big. I can do something in this world.

13. Any plans after college?

Not yet. I want to do something not physics, but I will try to be useful to the world as a physicist. After college I want to learn languages–French, Spanish, Mandarin, Chinese, Japanses, Italian, and German.

14. What are your other interests?

I want to do photography and film. I want to make movies and cartoons. I have a WordPress blog about pictures. Last Wednesday I made one minute video using stop motion animation with my toys. I also make cartoons. My website is I bought the domain. The tagline is “adventure is in you and me.”

I also love Sudoku. I have three trophies at home: one first place and two third place in the nationwide competion. That was when I was in third year high school. Do you know Sarah Cua? She is the Sudoku champion. She was not anymore asked to join this year. In the news articles, I am only one of the details about Sarah Cua. I went to the World Sudoku championship twice. The third world Sudoku was in Czech Republic. The fourth was in India, Goa.

Ateneo Physics News: Thank you, Mariel, for the wonderful interview.

Mariel: Thank you, too, sir.