InGaAs image sensors operate in two spectral ranges, 0.9 to 1.67 µm and 0.9 to 2.55 µm. CMOS multiplexers concentrate the data from the diodes into a shift register for convenient data acquisition. Dark current can be reduced by the use of one or two-stage thermoelectric coolers, capable of cooling to -20 °C. Hermetically sealed and lower cost ceramic DIP packages are available. InGaAs image sensors are used for near infrared (NIR) spectrophotometry, industrial inspection and as channel monitors in dense wavelength division multiplexing (DWDM).
