All-optical modulation in Mid-Wavelength Infrared using porous Si membranes

作者：Park Sung Jin; Zakar Ammar; Zerova Vera L; Chekulaev Dimitri; Canham Leigh T; Kaplan Andre^*

来源：Scientific Reports, 2016, 6(1): 30211.

DOI：10.1038/srep30211

We demonstrate for the first time the possibility of all-optical modulation of self-standing porous Silicon (pSi) membrane in the Mid-Wavelength Infrared (MWIR) range using femtosecond pump-probe techniques. To study optical modulation, we used pulses of an 800 nm, 60 femtosecond for pump and a MWIR tunable probe in the spectral range between 3.5 and 4.4 mu m. We show that pSi possesses a natural transparency window centred around 4 mu m. Yet, about 55% of modulation contrast can be achieved by means of optical excitation at the pump power of 60 mW (4.8 mJ/cm(2)). Our analysis shows that the main mechanism of the modulation is interaction of the MWIR signal with the free charge carrier excited by the pump. The time-resolved measurements showed a sub-picosecond rise time and a recovery time of about 66 ps, which suggests a modulation speed performance of similar to 15 GHz. This optical modulation of pSi membrane in MWIR can be applied to a variety of applications such as thermal imaging and free space communications.

• 出版日期2016-7-21