One-Dimensional Photonic Crystal with a Defect Layer Utilized as an Optical Filter in Narrow Linewidth LED-Based Sources

A one-dimensional photonic crystal (1DPhC) with a defect layer is utilized as an optical filter in a simple realization of narrow linewidth LED-based sources. The 1DPhC comprising TiO(2 )and SiO2 layers is characterized by two narrow defect mode resonances within the 1DPhC band gap, or equivalently, by two peaks in the normal incidence transmittance spectrum at wavelengths of 625.4 nm and 697.7 nm, respectively. By combining the optical filter with LEDs, the optical sources are employed in interferometry experiments, and the defect mode resonances of a Lorentzian profile with linewidths of 1.72 nm and 1.29 nm, respectively, are resolved. In addition, a simple way to tune the resonances by changing the angle of incidence of light on the optical filter is demonstrated. All-dielectric optical filters based on 1DPhCs with a defect layer and combined with LEDs thus represent an effective alternative to standard coherent sources, with advantages including narrow spectral linewidths and variable output power, with an extension to tunable sources.

Automated summary

A one-dimensional photonic crystal (1DPhC) with a defect layer is used as an optical filter for narrow linewidth LED-based sources. The 1DPhC consists of TiO2 and SiO2 layers and exhibits two narrow defect mode resonances. By combining the optical filter with LEDs, interferometry experiments are conducted and the Lorentzian profile defect mode resonances with linewidths of 1.72 nm and 1.29 nm are successfully resolved. Additionally, a simple method to tune the resonances by changing the angle of incidence of light is demonstrated. All-dielectric optical filters based on 1DPhCs with a defect layer and combined with LEDs provide an effective alternative to standard coherent sources, offering advantages such as narrow spectral linewidths and variable output power, with the potential for tunability.