All-Optical Modulation and Ultrafast Switching in MWIR with Sub-Wavelength Structured Silicon

Applied Sciences

Dimitri Chekulaev¹  Jack Collins²  Rihan Wu²  Andrey Kaplan² 

[1] Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK;School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK;

关键词: ultrafast;    all-optical modulation;    MWIR modulator;    sub-wavelength structured silicon;   

DOI  :  10.3390/app9091808

来源: DOAJ

【 摘 要 】

We investigated and optimised the performance of the all-optical reflective modulation of the Mid-Wave Infrared (MWIR) signal by means of the optically-pumped sub-wavelength-structured optical membranes made of silicon. The membranes were optically pumped by a 60-femtosecond, 800-nm laser, while another laser operating in the MWIR ranging between 4 and 6 $\mathsf{\mu }$ m was used to probe the optical response and modulation. We were able to achieve the conditions providing the modulation depth of 80% using the pump fluence of 3.8 mJ/cm ${}^2$ . To get a better insight into the performance and the modulation mechanism, we developed an optical model based on a combination of the Wentzel−Kramers−Brillouin approximation, Drude and Maxwell−Garnett theories. The model allowed us to estimate the values of the dielectric function, carrier concentration and scattering rate of the optically-excited membrane in the MWIR range. Using the model, we optimised the performance and found the conditions at which the reflective modulation can be operated with the ultrafast response of 0.55 ps and modulation contrast of 30%.

【 授权许可】

Unknown