Carlos Owusu-Ansah

The trajectory of an Anisotropic Particle Near a Light-Transmitting Optical Nanofiber

April 3, 2021   /  

Name: Carlos Owusu-Ansah
Majors: Physics, Mathematics
Advisors: Dr. Cody Leary, Dr. Robert Kelvey

Hi, I am Carlos. I love to do research. When I am not working on research or studying, I like to explore the world. Recently, I started taking long bike rides in my neighborhood. I got lost a few days ago, and since I had left my phone at home, I had to ask for directions from friendly neighbors. My IS project was about the interaction between visible light and small particles. We model an experiment where red light is transmitted through a thin optical fiber. As it travels through the optical fiber, it leaks out and affects the motion of a nearby tiny particle. We derive equations that describe the behavior of the particle and use those equations to predict the behavior of a kyanite particle when it is close to the optical fiber. We find that the light causes the kyanite particle to follow a helical trajectory along the surface of the optical fiber. As the kyanite particle moves along the fiber, it also vibrates.We hope that experiments can be designed to probe our results in the lab, but we are not certain of this because the vibrations we are predicting are very small.

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Carlos will be online to field comments on April 16:
4-6 pm EDT (PST 1pm-3pm, Africa/Europe: late evening)

43 thoughts on “The trajectory of an Anisotropic Particle Near a Light-Transmitting Optical Nanofiber”

  1. Hi Carlos- This looks like a cool project. I love that you are so interested in learning and exploring. All the best to you in your future endeavors!

  2. Carlos, congratulations! This is an interesting project – thanks for sharing all your hard work. Since the transmitted red light affects the motion of a nearby small particle, can you speculate how we might apply these ideas to use light to move a nearby large object? I’m looking forward to the day you can develop for us a sort of ‘ray gun’ that can help move heavy objects. Is that theoretically possible?

    1. haha. Thanks so much for going through it. I think it may be theoretically possible to move large objects with low frequency and high-intensity beams. Low frequency because you want to give the object time to react to the acceleration from the electric field and high-intensity because you will need a strong electric field to move a large object. This is just a guess. I am not really sure, but I think it should be theoretically possible to scale things up.

  3. Congratulations, Carlos, on completing your IS! All my best wishes for graduate school!

  4. Congratulations, Carlos! This is very interesting work! I had a question about the oscillations you see in your analysis. You noted that you see different patterns in those oscillations depending on the timescale you select Is there one shortest time scale where it appears you are able to see all the detail of the oscillations? It sounds like there are still more interesting results to be discovered in understanding these trajectories!

    Great work on your IS, and all the best for the future!

    1. Hi Dr. Bolton! Thanks for the great question! And thank you so much for coming to see this work.

      The truth is I don’t fully understand the nature of the oscillations. The reason they are hard to interpret is that we are not really measuring the vibrations directly because those are so small compared to other length scales in the theoretical experiment. The oscillations are an effect of the vibrations. There is definitely a lot more work to be done here. Perhaps there is a time scale that captures all the detail in the oscillations. I would have to think about that some more.

  5. First and foremost, I love your abstract. Really speaks to the wonder you have for the world. As for your I.S., I love the way you’ve blended math as a means of understanding or succinctly modeling the characteristics of the particles. A great way of combining the two fields, where one enhances the understanding of the other. Great project, amazing execution, and brilliant presentation. Thank you for showing a practical interdisciplinary approach to math, Carlos. I would not put a project of this caliber past you. Honored to have done research with you during our summer at OSU, and truly in awe to call you a friend!!

  6. Hello Carlos, this is a great presentation. I read that you were unable to test your experiment in a lab, but I have heard of a study conducted to use the reflection of light to push low-mass sails which could potentially be used to propel spacecraft. Have you ever seen this study before, and could it be used by you as a basis to conducting your future lab experiment?

    1. Hey Zach! thanks so much for going through this work.

      Yesss. I have seen that. It’s so cool. There is a lab in Japan with all the resources necessary to test out our predictions. Maybe they will take it on.

  7. Congratulations Carlos!! Wishing you the very best from Wooster and hoping to see you very soon!!

  8. Hey Carlos! I am so impressed but not at all surprised by the thoughtfulness of your project and the quality of this poster!!! One question: what do you think would happen if you were to analyze the vibrations directly? I’m so excited for all that is to come at OSU and how you will continue to make a difference in the world around you. Can’t wait to see you soon, God willing!

    1. Thank you, Gracie. That’s a great question. Thanks for the kind words. See you soon!

      I think an analogy might help explain. Imagine a super bright light source like the sun with a tiny flicker that is about 0.0001% of its intensity. It would be hard to notice the flicker by just looking at the light source. But if you could reduce the average brightness of the light source, so that the flicker causes a much bigger change in the relative brightness, then you would be able to notice the flicker. That’s similar to what we are doing here: since the vibrations are so small compared to the displacement of the particle, we are trying to filter out the displacement in the particle that is not caused by the vibrations. Hope this makes sense.

  9. I’m fascinated by your project! I’m sure it was difficult to do this work exclusively conceptually, so congratulations on your hard work. What are the potential applications of anisotropic particles, beyond maybe aesthetics?

    1. Thanks for coming Janelle! And thanks for your kind words.

      Most crystals are anisotropic either because of the way they are shaped or the arrangement of their molecules. So learning how to move anisotropic crystals with light has plenty of potential applications. Sometimes physical tweezers are too cumbersome to be used for small particles, and it would be great if light could be used to move particles.

  10. Great work on this project, Carlos! Is the lack of detectable vibrations beneficial for applications of the optical fiber or are there circumstances when it would be desirable?

    1. Hi Dr. Feierabend. Thank you for coming around to check this out.

      Some scientists think it may be possible to use the interaction between anisotropic particles and optical nanofibers to improve our understanding of light by distinguishing between its spin and
      orbital angular momentum components. If this is the goal, then it will be important to be able to detect the vibrations and compare experiments with theoretical predictions.

      But if the focus is on moving particles from one place to another, then the absence of detectable vibrations is not as important, and may even be beneficial.

  11. Nice work Carlos! If you have more time, what would you investigate next in this project?

    1. Thanks, Dr. Leary – couldn’t have done it without your help.

      I think I would work on understanding what the vibrations really look like. Also, I would change the parameter space to see what other motions are possible.

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