MWIR optical modulation using structured silicon membranes

Canham

et al. 2018

Applied Sciences

We present an experimental investigation into the third-order nonlinearity of conventional crystalline (c-Si) and porous (p-Si) silicon with Z-scan technique at 800-nm and 2.4- μ m wavelengths. The Gaussian decomposition method is applied to extract the nonlinear refractive index, n 2 , and the two-photon absorption (TPA) coefficient, β , from the experimental results. The nonlinear refractive index obtained for c-Si is 7 ± 2 × 10 − 6 cm 2 /GW and for p-Si is − 9 ± 3 × 10 − 5 cm 2 /GW. The TPA coefficient was found to be 2.9 ± 0.9 cm/GW and 1.0 ± 0.3 cm/GW for c-Si and p-Si, respectively. We show an enhancement of the nonlinear refraction and a suppression of TPA in p-Si in comparison to c-Si, and the enhancement gets stronger as the wavelength increases.

Section: Introductionmentioning

confidence: 99%

The Influence of Quantum Confinement on Third-Order Nonlinearities in Porous Silicon Thin Films

Canham

et al. 2018

Applied Sciences

“…The optical membranes used in this work are similar to those presented in our report. 11 Briefly, the optical membranes were made by photoelectrochemical etching of ordered 2D hole array in a thin (a few tens of microns) silicon slab using HF acid. A fabrication procedure employed in this work is similar to that described previously.…”

Section: Methodsmentioning

confidence: 99%

“…The principle of the modulator work was reported previously. [9][10][11] Briefly, the core of the modulator is a silicon photonic membrane consisting of 2D periodically arranged holes. Due to the photonic properties of the structure, the membrane reflects less and transmits more IR light than a bare silicon window of the same thickness.…”

Section: Introductionmentioning

confidence: 99%

Demonstration of time-of-flight technique with all-optical modulation and MCT detection in SWIR/MWIR range

Emerging Imaging and Sensing Technologies for Security and Defence III; And Unmanned Sensors, Systems, and Countermeasures

Burgess³

et al. 2018

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“…However, the modulator operation/repetition frequency was limited by the recombination time required for the modulator to return to the unexcited state before the next switching event happened. In our previous work, we showed that the complete recombination of the excited carriers occurred on the nanosecond time scale [35].…”

Section: Demonstration Of the Ultrafast Switchingmentioning

confidence: 97%

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

Chekulaev

et al. 2019

Applied Sciences

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 μ 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%.