Compact and ultrathin back-reflection grating spectrometer with improved spectral resolution

Handheld spectrometers have been reduced in size due to advanced microfabrication processes, but have significantly poor spectral resolution compared to conventional spectrometers. Here we report compact and ultrathin spectrometer that improves optical performances in visible region. Designed spectrometer improves low spectral resolution and high optical sensitivity through the back-reflection grating structure. Spectrometer is fabricated with the ultrathin structure with the overall thickness of 6 mm. With these simple internal optical elements, this compact and ultrathin spectrometer can be utilized in non-invasive biomonitoring sensor.