Angelmahr, MartinMartinAngelmahrMiklos, AndrásAndrásMiklosHess, PeterPeterHess2022-03-042022-03-042008https://publica.fraunhofer.de/handle/publica/21598610.1364/AO.47.002806Photoacoustic (PA) spectra generated by current modulation of a distributed feedback diode laser (DFB-DL) were measured for the ammonia absorption line at 1.53 mu m and calculated using absorption spectra taken from a database. The algorithm is based on a combined amplitude- and wavelength-modulation (AM-WM) scheme. The spectral characteristics of the DFB-DL were determined by comparing simulated spectra with Fourier transform infrared measurements. PA spectra were measured and simulated from the first to fourth harmonic and a variation of the modulation depth with modulation frequency was observed. It was found that combined AM-WM modulation may produce larger PA signals than separate AM or WM detection for the first harmonic.en690535journal article