Spatially and spectrally stable semiconductor light sources for near infrared spectroscopy

LEDs have narrow radiation bandwidth which should be broadened for use them in near infrared spectroscopy. The well-known methods are not satisfactory for this purpose. We modified the output spectrum of the GaInAsP/InP LED chip by introducing wavelength converter layers into a normal LED structure outside from p-n junction. LEDs with luminescent layers made by us have spatially and spectrally stable structure, negligible current and temperature dependence. We made LEDs with two luminescent layer with new improved wavelength converter system which has further advantages and good efficiency.