Application of Arrayed-Waveguide Grating to Compact Spectroscopic Sensors

An arrayed-waveguide grating (AWG) fabricated using silica-based waveguides has good stability, good channel uniformity, high wavelength accuracy and low cost. The AWG is attractive not only for use in optical wavelength-division-multiplexed networks but also for potential applications to various spectroscopic measurements. We propose a compact spectroscopic sensor based on the AWG, and fabricated an AWG module for sensing. A liquid sample under test is poured into a groove in the first slab region of the AWG. The detector that is placed at the end face of the second slab region measures the spectral transmittance of the liquid. A preliminary experiment was carried out using the water solution of sodium acetate. We achieved the relative error in terms of the optical transmittance of 2.5%. Fundamental device characteristics and preliminary experimental results are reported.