Distributed Bragg Reflector Filter

Application ID: 22561

A distributed Bragg reflector (DBR) is a periodic structure formed from alternating dielectric layers that can be used to achieve nearly total reflection within a range of frequencies. The main advantage of DBRs over ordinary metallic mirrors is that DBRs can be engineered to have custom reflectances at selected wavelengths.

This application allows the performance of two different kinds of DBR filters to be simulated and characterized: Band-stop filters and Notch filters.

A band-stop filter prevents wavelengths within the range of the stop-band from transmitting. This is useful for filtering out unwanted wavelength regions from a spectrum. Band-stop filters are commonly included in many kinds of optical measurement setups, where they are used to prevent stray laser light from entering the sensitive detector equipment.

A notch filter allows a narrow range of wavelengths to pass while reflecting all other wavelengths. This is useful for selecting emission from a spectrally narrow source, such as individual transitions in a gas, while rejecting optical contamination from other emission sources.

The inputs to this application configure the properties of the geometry and the layer refractive indices.Results are presented as plots of the reflectance over a range of radiation wavelengths. The width of the stop-band is presented for both filter cases, while the reflectance of the notch and the width of the notch pass-band is also calculated.

This application example illustrates applications of this type that would nominally be built using the following products: