Source: TG Daily
Physicists at Rutgers University, NASA¡¯s Jet Propulsion Laboratory and the State University of New York at Buffalo have developed a nano-sized electronic circuit, which can detect light invisible to the human eye and today¡¯s radio telescopes, opening an opportunity to analyze the greatest portion of the light emitted since the ¡°big bang¡± and gain insights into the earliest stages of star and galaxy formation almost 14 billion years ago.
The researchers said that their tiny new circuit is about 100 times smaller than the thickness of a human hair. It is sensitive to faint traces of light in the far-infrared spectrum, well beyond the colors humans see. They believe the technology is sophisticated enough to develop a new generation of much more light-sensitive space telescopes to gather light that cannot be detected today.
In fact, it is estimated that sub-millimeter or terahertz region of the electromagnetic spectrum, which is targeted by this device, contains approximately half of the total luminosity of the Universe and 98% of all the photons emitted since the Big Bang. Since the Earth¡¯s atmosphere absorbs far-infrared light, Earth-based radio telescopes cannot detect the very faint light emitted by the earliest stars of the universe, the researchers said. This fact
¡°In the expanding universe, the earliest stars move away from us at a speed approaching the speed of light,¡± said Michael Gershenson, professor of physics at Rutgers and one of the lead investigators. ¡°As a result, their light is strongly red-shifted when it reaches us, appearing infrared.¡±
Today¡¯s detectors of infrared and sub-millimeter waves, commonly referred to as bolometers, measure the heat generated when they absorb photons, or units of light. However, the scientists said that today¡¯s bolometer has hit a wall and is unlikely to see any significant performance improvements in the future. They claim that the new device, called ¡°hot-electron nanobolometer,¡± is potentially 100 times more sensitive than existing bolometers and is said to be ¡±faster to react to the light that hits it.¡±
The nanobolometer was built using built it using thin-film and nanolithography techniques similar to those used in computer chip fabrication and measures about 500 nm long and 100 nm wide. It is constructed from titanium and niobium metals and operates at a temperature of about 459 degrees below zero Fahrenheit, or one-tenth of one degree above absolute zero on the Kelvin scale.
According to the researchers, photons striking the nanodetector heat electrons in the titanium section, which is thermally isolated from the environment by superconducting niobium leads. By detecting the infinitesimal amount of heat generated in the titanium section, they are able to measure the light energy absorbed by the detector. Apparently, the device can detect as little as a single photon of far infrared light.
¡°With this single detector, we have demonstrated a proof of concept,¡± Gershenson said. ¡°The final goal is to build and test an array of 100 by 100 photodetectors, which is a very difficult engineering job.¡±
What a fascinating time we live in.