A Photonics Enabled Millimetre Wave Frequency Domain Spectrometer for Glucose Concentration Sensing

This study reports the experimental demonstration of a free space frequency domain self-heterodyne spectrometer utilising a high-speed Uni- Travelling Carrier photodiode (UTC-PD) as a coherent receiver. The transmission signal through the glucose solution was measured in the V-band (50 - 75 GHz) frequency range with a frequency resolution step of 40 MHz. Variations in glucose concentrations of as small as 1 % weight were resolved.