The reflectivity () of the DBR is given by
where and are the respective refractive indices of the surrounding medium, the two alternating materials, and the substrate; and is the number of repeated pairs of low/high refractive index material.
The bandwidth of the photonic stopband can be calculated by
Thus increasing the number of pairs in a DBR increases the mirror reflectivity and increasing the refractive index contrast between the materials in the Bragg pairs increases both the reflectivity and the bandwidth.
Distributed Bragg reflectors are critical components in vertical cavity surface emitting lasers and other types of narrow-linewidth laser diodes such as distributed feedback lasers. They are also used to form the cavity resonator (or optical cavity) in fiber lasers and free electron lasers.
This section discusses the interaction of Transverse Electric and Transverse Magnetic polarized light with the DBR structure, over several wavelengths and incidence angles. This reflectivity of the DBR structure (described below) was calculated using the transfer-matrix method (TMM), where the TE mode alone gets highly reflected by this stack, while the TM modes are passed through. This also shows the DBR acting as a polarizer.
For TE and TM incidence we have the reflection spectra of a DBR stack, corresponding to a 6 layer stack of dielectric contrast of 11.5, between an air-dielectric layers. The thickness of air layer is 0.8 of the period, and dielectric is 0.2 of the period. The wavelength in the figures below, correspond in multiples of the cell-period.
This DBR also corresponds to a simple example of 1D Photonic Crystal's that have only a complete TE band gap, while only a pseudo TM band gap.
US Patent Issued to National Central University on Aug. 24 for "Method for Fabricating Distributed Bragg Reflector Waveguide" (Taiwanese Inventors)
Aug 25, 2010; ALEXANDRIA, Va., Aug. 31 -- United States Patent no. 7,783,151, issued on Aug. 24, was assigned to National Central University...
US Patent Issued to Seoul Opto Device on Feb. 12 for "Light Emitting Diode Having Distributed Bragg Reflector" (South Korean Inventors)
Feb 14, 2013; ALEXANDRIA, Va., Feb. 14 -- United States Patent no. 8,373,188, issued on Feb. 12, was assigned to Seoul Opto Device Co. Ltd....
WIPO ASSIGNS PATENT TO SEOUL OPTO DEVICE FOR "LIGHT EMITTING DIODE CHIP HAVING DISTRIBUTED BRAGG REFLECTOR AND METHOD OF FABRICATING THE SAME" (SOUTH KOREAN INVENTORS)
Aug 24, 2011; GENEVA, Aug. 24 -- Publication No. WO/2011/099771 was published on Aug. 18. Title of the invention: "LIGHT EMITTING DIODE CHIP...
WIPO PUBLISHES PATENT OF SEOUL OPTO DEVICE FOR "LIGHT EMITTING DIODE HAVING DISTRIBUTED BRAGG REFLECTOR" (SOUTH KOREAN INVENTORS)
Feb 07, 2012; GENEVA, Feb. 7 -- Publication No. WO/2012/015153 was published on Feb. 2. Title of the invention: "LIGHT EMITTING DIODE HAVING...