Fabrication of Bragg Gratings Using Interferometric Lithography

A setup has been designed and realized for the fabrication of Bragg Gratings in edge emitting semiconductor laser. In this setup a HeCd laser, at 325nm, is used in a Lloyd’s mirror configuration, to interferometrically expose a sinusoidal grating on photoresist…


Chapter 1: Introduction/Motivation
Chapter 2: Theory
2.1. Bragg Gratings
2.1.1. Introduction
2.1.2. Periodic Waveguide
2.1.3. Effective Index Method for DBR laser
2.1.4. Finite Length Gratings
2.2. Standing Wave
2.2.1. Interference of Light
2.2.2. Unwanted Standing Wave
Chapter 3: Experimental Setup / Desig.
3.1. Lloyd’s Mirror Setup
3.2. Propagating a Gaussian
3.2.1. Laser Cavity
3.2.2. Aperture to Lens
3.2.3 Lens to Lloyd’s Mirror
3.2.4 Pinhole size
3.3. Mirror
3.3.1. Aligning Lloyd’s Mirror
3.3.2. Angle Calibration
3.3.3. Range of angles
3.4. Variation across Sample
3.4.1. Intensity of Electric Field
3.4.2. Grating Period
3.5. Grating Period Measurement
3.5.1. Alternate Setup
3.5.2. Limit to Grating Measurement
3.5.3. Making a measurement
Chapter 4: Fabrication
4.1. Preparing the Sample
4.2. Exposing Positive Resist using Lloyd’s Mirror
4.2.1. Turning the Laser On
4.2.2. Loading the Sample
4.2.3. Getting Flat Bottoms
4.3. Etching Gratings into Semiconductor
Chapter 5: Conclusion

Author: Pizarro, Ricardo Andres

Source: University of Maryland

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