Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems

Abstract EN

A compact instrument consisting of a distributed feedback laser (DFB) at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS) technique.

The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively.

Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C.

For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal.

In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS) technique involving extraction of harmonic signals.

The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition.

This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.