Experiment setup for optical tweezer experiment.
Experiment setup for lock-in and Hall effect experiment.
Experiment setup for photoluminescence experiment.
Experiment setup for single photon interference experiment.
Lecturer: Prof. Changyoung Kim
Colleagues: Jaewon Jung*, Juwon Choi, Junyoung Lee, and Hyeonsung Jo
Contributions: J. Jung constructed measurement protocols using a Python module, PyVISA and conducted measurements. All the students contributed equally to the experiment setup. Attached reports are my individual works.
Intermediate Physics Laboratory 1 Spring Semester 2024
Optical Tweezer*
In this experiment, we utilized an optical tweezer system to manipulate and trap small particles, such as polystyrene beads of varying diameters (0.75 μm, 2 μm, and 3 μm). The 658 nm laser was used to observe Brownian motion and measure trapping forces. By analyzing the beads’ Brownian motion, we were able to calculate the viscosity of the surrounding fluid and estimate the trapping force, which was in the piconewton range. This experiment also involved statistical techniques like Gaussian fitting and bootstrapping to ensure the observed Brownian motions closely matched theoretical predictions.
Lock-in Detection and Hall effect*
In this experiment, we employed lock-in detection techniques to measure the small Hall voltage in a noisy environment. After calibrating the components of the lock-in amplifier, we measured the magnetic fields of two cylindrical neodymium magnets across different axes using a GaAs Hall sensor. The magnetic moment of the magnets was calculated based on the geometry of the magnet, and the results were consistent with theoretical models.
Photoluminescence*
In this experiment, we measured the photoluminescence (PL) signals from Rhodamine 590 and ruby crystals under varying temperature and pressure conditions. Using a 532 nm laser, we captured PL spectra and analyzed the emission properties, such as Stokes sidebands and R-lines in the ruby crystal. We explored the molecular band structures and used the Debye theory to explain the observed temperature dependence of the spectral lines, finding good agreement with theoretical predictions.
Single Photon Interference*
This experiment recreated Young’s double slit experiment to demonstrate the wave-particle duality of light using two different light sources: a 670 nm laser and a 546 nm bulb dimmed to approach the single-photon limit. We measured diffraction and interference patterns, confirming the wave-like behavior of light in the laser experiment and validating the single-photon interference limit using Poisson distributions and noise filtering. The experiment also implemented Feynman’s path integral formulation to analyze the observed interference fringes.