Distributed Bragg reflector

<p>A distributed Bragg reflector (DBR) is a <a href="/facts/Reflection_(physics)/BhcjDs79">reflector</a> used in <a href="/facts/Waveguide_(optics)/CQ6AnRAl">waveguides</a>, such as <a href="/facts/Optical_fiber/5ruuIFbj">optical fibers</a>. It is a structure formed from multiple layers of alternating materials with different <a href="/facts/Refractive_index/yjkzvgeE">refractive index</a>, or by periodic variation of some characteristic (such as height) of a dielectric waveguide, resulting in periodic variation in the effective refractive index in the guide. Each layer boundary causes a partial reflection and refraction of an optical wave. For waves whose vacuum <a href="/facts/Wavelength/kcJU0ymz">wavelength</a> is close to four times the <a href="/facts/Optical_path_length/qpXIMzqz">optical thickness</a> of the layers, the interaction between these beams generates <a href="/facts/Constructive_interference/lI5f78I4">constructive interference</a>, and the layers act as a high-quality reflector.  The range of wavelengths that are reflected is called the photonic <a href="/facts/Stopband/rfIhELus">stopband</a>. Within this range of wavelengths, light is "forbidden" to propagate in the structure.
</p>

Distributed Bragg reflector open-in-new

Distributed Bragg reflector