Bioplastic Diffraction Gratings Based On Chitosan Extracted from Crab Shell Waste

The Department of Physics
School of Science and Engineering

invites the public to the dissertation defense titled

“Bioplastic Diffraction Gratings Based On Chitosan Extracted from Crab Shell Waste” 

by

MR. EFREN G. GUMAYAN

PhD Physics Student

on

March 24, 2023 (Friday)
2:00 PM to 4:00 PM
Online via Zoom
Join the session by scanning the QR code on the poster.

 Adviser

 Raphael A. Guerrero, PhD

Panel Members

Caironesa P. Dulpina, PhD
Ramon M. delos Santos, PhD
Ian Ken D. Dimzon, PhD
Joel T. Maquiling, PhD

Abstract

A bioplastic diffraction grating made of chitosan extracted from crab shell wastes is fabricated using simple soft lithography. Bioplastic gratings are replicated from PDMS master grating replicas with groove densities of 600 lines/mm and 1200 lines/mm. Imaging with atomic force microscopy revealed the successful copying of triangular groove structures with the correct periodicity on the chitosan replicas. Fidelity of the replication process and diffraction performance of the bioplastic gratings were confirmed through diffraction experiments using a laser source with the beam at normal incidence to the grating. With a 514.5 nm laser wavelength, the bioplastic replica with 600 lines/mm exhibited a first-order diffraction angle θ = 18.4⁰, only 2% higher than the theoretical value (18⁰). On the other hand, the bioplastic grating with 1200 lines/mm produced a first-order diffraction angle θ = 38.9⁰, differing from the theoretical value (38.1⁰) by only 2%.  Using a laser operating at 632.8 nm, the first-order diffraction angle for the 600 lines/mm bioplastic grating was θ = 23.3⁰, deviating from the theoretical value (22.3⁰) by 4.6%.  At the same wavelength, the 1200 lines/mm bioplastic replica had a first-order diffraction angle θ = 51.5⁰, higher than the theoretical value (49.4⁰) by 4.3%.  Power efficiency of bioplastic gratings was found to be comparable with the output of PDMS master gratings. At 514.5 nm, power efficiency of a bioplastic grating was 0.2% and 0.3% for 600 lines/mm and 1200 lines/mm, respectively. Power efficiency at 632.8 nm was found to be 0.2% for both groove densities.