Design and Simulation of a Band Pass Fabry-Perot Filter
Design and Simulation of a Band Pass Fabry-Perot Filter
“A.A. Cruz
The University of Alabama in Huntsville Physics Department,
137 Madison Hall Huntsville, Al 35899, US
April 2009.”
Abstract
In this study, a novel design of a Fabry-Perot band pass filter using as low and high index coating materials silicon dioxide (SiO2) and titanium dioxide (TiO2) is presented. Two high reflectance dielectric materials separated by a half wavelength “cavity” which is made up of SiO2 that allows light surrounding the central wavelength (550 nm) to be transmitted partially while the remaining spectrum range outside the bandwidth to be almost totally reflected. The matrix approach is the physical tool utilized to get the complex expressions that explains this behavior. The maximum transmittance peak achieved was 95.72 %, bandwidth at -3dB : 2.98 nm and bandwidth at -20 dB : 10.40 nm.
A further analysis is done by increasing the number of cavities or spacers from a single to a double one and letting them have the same thickness as the first configuration. A simulation using C++ programming shows that a better and steeper slope is gotten letting the energy spectrum range within the bandwidth to be transmitted more efficiently.
Key words: multilayer antireflection coatings, band pass filter, narrow band pass filter, Fabry-Perot filter, multi-cavity Fabry-Perot filter.
1. Introduction
An optical band pass filter (BPF) is a device that allows a certain range of electromagnetic frequencies to be transmitted and the other ones to be rejected. This range varies according to our needs and what the filter will be used for. They’re a key component for optical communications devices, laser- line cleaning and medical imaging apparatus.
Currently, were facing an era where technology and high quality devices work together in such a way that the more advanced and accurate technology we work with the better the performance of the apparatus with can can build.
“A.A. Cruz
The University of Alabama in Huntsville Physics Department,
137 Madison Hall Huntsville, Al 35899, US
April 2009.”
Abstract
In this study, a novel design of a Fabry-Perot band pass filter using as low and high index coating materials silicon dioxide (SiO2) and titanium dioxide (TiO2) is presented. Two high reflectance dielectric materials separated by a half wavelength “cavity” which is made up of SiO2 that allows light surrounding the central wavelength (550 nm) to be transmitted partially while the remaining spectrum range outside the bandwidth to be almost totally reflected. The matrix approach is the physical tool utilized to get the complex expressions that explains this behavior. The maximum transmittance peak achieved was 95.72 %, bandwidth at -3dB : 2.98 nm and bandwidth at -20 dB : 10.40 nm.
A further analysis is done by increasing the number of cavities or spacers from a single to a double one and letting them have the same thickness as the first configuration. A simulation using C++ programming shows that a better and steeper slope is gotten letting the energy spectrum range within the bandwidth to be transmitted more efficiently.
Key words: multilayer antireflection coatings, band pass filter, narrow band pass filter, Fabry-Perot filter, multi-cavity Fabry-Perot filter.
1. Introduction
An optical band pass filter (BPF) is a device that allows a certain range of electromagnetic frequencies to be transmitted and the other ones to be rejected. This range varies according to our needs and what the filter will be used for. They’re a key component for optical communications devices, laser- line cleaning and medical imaging apparatus.
Currently, were facing an era where technology and high quality devices work together in such a way that the more advanced and accurate technology we work with the better the performance of the apparatus with can can build.
References: [1] Hecht E. Optics 4th ed. California US. Pearson Addison Wesley. 2002. 426, 427, 428, 429, 430. [2] Mikhail Polyanskiy. Refractive Index Database. April, 2009. http://refractiveindex.info/index.php?group=CRYSTALS&material=TiO2&option=HO&wavelength=6.18 [3] Mikhail Polyanskiy. Refractive Index Database. April, 2009. http://refractiveindex.info/index.php?group=CRYSTALS&material=SiO2&option=o&wavelength=1.5