To study the effect of change in incident angle on the optical properties of a DBR

Presented by:

Muzammil Khan

Department of Electronic Engineering, BUITEMS

Contents

Motivation

Introduction

Methodology

Results & discussion

Conclusion

References

Motivation

Distributed Bragg reflector(DBR) used to make the partially reflected mirrors which have broad applications in optics. DBR are also used as waveguide in fibre optics. DBR are being used in interferometers which are then being used in spectroscopy.

DBR used in formation of optical filters which are tunable over a wide bandwidth and can be used to pass or reflect the desired amount of light or to focus the light of desired wavelengths.

This lab purpose is to learn broad prospective of the DBR and to provide the insight to the different optical properties of it.

Introduction DBR (Distributed Bragg Reflector) is a reflector which is formed by the multiple

layers of different materials of varying refractive index and produce the partially reflected mirrors. The properties of material such that material thickness or refractive index or the gap between the respective layers can be varied depending upon the applications of DBR mirrors. DBR provide high reflectivity and finite absorption as well.

Methodology

Create a new project in “Open filter” software.

Then add filter in it and select the range of the central wavelength upto 550nm.

Then create stack formula in a filter. Use (HL) for single and (HL)^2 for 2 layers.

Took dielectric material SiO2 and air whose refractive index is 1.42 and 1.

The symbol “H” is used for SiO2 and “L” for air respectively.

Then click on analyse and calculate reflection, as well as changing the incident angle start from zero, 30 degree, 45 degree and 90 degree.

Results & Discussion Results showed below tells us about the comparison of reflection at different

incident angle used in DBR.

Through this we can say that changing the incident angle will makes the reflectivity wider.

When 2 pair of SiO2 and air used and central wave length is 550 nm and incident angle is 0 degree the results becomes.

Results & Discussion

When 2 pair of SiO2 and air used and central wave length is 550 nm and incident angle is 45 degree the results becomes

When 2 pair of SiO2 and air used and central wave length is 550 nm and incident angle is 30 degree the results becomes

Results & Discussion

When 2 pair of SiO2 and air used and central wave length is 550 nm and incident angle is 89 degree the results becomes

In last when all the results are combined is show that how the reflection increases with the change in incident angle.

Conclusion

From this lab we concluded that as the incident angle is changing from 0 degree to 89degree the reflectivity increases.

changing the incident angle will change the output of DBR.

90 degree is parallel with DBR so light don’t pass through DBR and no result is shown means no reflectivity with 90 degree

References Lab lectures by DR. Anayat.

Optical effects in solids book by David B. Tanner.

THANKS