News Excerpt:
Researchers at the Indian Institute of Science (IISc) have successfully fabricated a device that can up-convert the frequency of short infrared light to the visible range.
More about the Device:
- The human eye can only detect light within the visible spectrum, with red light at the lowest frequency. Infrared light, which is invisible to the naked eye, has a frequency even lower than that of red light.
- The device increases or up-converts the frequency of short infrared light to the visible spectrum.
- The researchers used a 2D material to design a non-linear optical mirror stack to achieve this up-conversion.
- This device also features widefield imaging capability.
- The mirror stack comprises multilayered gallium selenide attached to a gold reflective surface, with a silicon dioxide layer sandwiched between them.
Significance of the breakthrough:
- It has potential for applications in defense and optical communications.
- Traditional infrared imaging techniques rely on low-energy bandgap semiconductors or micro-bolometer arrays that detect heat or absorption signatures from the object under observation.
- However, these infrared sensors are often bulky, inefficient, and export-restricted due to their defense applications. There is a pressing need for indigenous and efficient alternatives.
- The IISc team's method involves directing an input infrared signal and a pump beam onto the mirror stack.
- The non-linear optical properties of the stack's material mix the frequencies, producing an output beam of higher (up-converted) frequency while retaining its other properties.
- This technique enabled the up-conversion of infrared light with a wavelength of approximately 1,550 nm to visible light at 622 nm, which can be detected using conventional silicon-based cameras.
- This device can help in doing infrared imaging without using infrared sensors.
Future scope of improvement:
- To extend the work to up-convert light of longer wavelengths.
- To improve the device's efficiency by exploring alternative stack geometries.
Conclusion:
This innovative approach by the IISc team represents a significant advancement in optical communications and infrared imaging, potentially transforming various applications in defense and beyond.
