Narrow-band detector for underwater communication system

There is growing interest in optical detectors for underwater communication and imaging systems [1]. Seawater is most transparent over the wavelength range of 450-550 nm, with the peak transmittance shifting to the longer wavelengths as the turbidity of the water increases from deep to coastal water [2]. Commercial silicon photodiodes typically have high efficiency of > 90% at such wavelengths however their broad spectral response which covers the entire visible spectrum introduces considerable noise to the system due to the presence of ambient light. While a narrow band-pass filter can be installed with the detector, this will introduce some attenuation and the filter peak transmittance will be sensitive to the light incident angle.