Real-time baseline correction technique for MWIR and LWIR time-resolved photoluminescence spectroscopy (Presentation Recording)

Abstract

The time-resolved photoluminescence (TRPL) measurement provides rich information about carrier dynamics and recombination mechanisms. However, TRPL measurements are quite challenging in mid-wave infrared (MWIR) and long-wave infrared (LWIR) regimes due to noise in photodetectors and data acquisition systems. Our analysis and experimental results show that the noise in a conventional TRPL system using a traditional averaging method is dominated by 1/f noise from 10 Hz to 3 kHz. The signal is also mixed with sub-Hertz noise associated with the boxcar baseline oscillation, commonly known as the “baseline drift” issue which results from numerous fluctuations in the system. A real-time baseline correction method is proposed and demonstrated to suppress these low frequency noise sources. The real-time baseline correction method is realized by modulating the signal. The modulation can be achieved by either electrical, mechanical, or optical approaches. Analysis indicates that the noise of this method is proportional to the noise spectral density at the modulation frequency, this argument is confirmed by the simulation results. The simulated noise achieved by the real-time baseline correction method is much lower than the traditional method. Experimental results show that the low frequency baseline oscillations associated with the traditional TRPL experiments are absent using the real-time baseline correction technique, and the noise of the measurement is significantly reduced. This work establishes a more efficient experimental method for TRPL measurements on weak MWIR and LWIR PL signals, such as the InAs/InAsSb type-II superlattice samples which are used here to demonstrate the proposed method.