NASA is developing a new type of probe that can observe the formation and structure of the universe, according to a report by McCombs consulting. The vast amount of radiation and mechanical interaction in the universe shapes the interstellar medium of galaxies and drives galaxy evolution (such as stellar winds and blast waves from jet streams, supernova explosions, etc.). This interaction can occur at 4. The best observation was obtained at 744 terahertz (THz) oxygen absorption spectrum. However, the spectral line was rarely observed in the past due to 4. The 744 terahertz frequency is beyond the sensitivity range of the local oscillator (LO) operating in most existing heterodyne receivers, and is not sufficient to support such observations. A nasa-funded team from the Massachusetts institute of technology (MIT) is working to advance the technology so that future NASA missions include receivers that can observe this important spectral line.
Heterodyne detection was based on the Heterodyne detection concept, which was based on the reference light of the local oscillator (LO). The main challenges of the project are: to increase the output power of the local oscillator from the current level of less than 1mW to 5mW, and to increase the operating temperature from the experimental 10K to 40K (which is the applicable temperature for space-based or suborbital observatories). As shown in the figure, the large circuit board on the left adopts the previous ASIC design; Three rectangular segments provide three antenna input terminals that can support 4 20MHz channels, and only need about 5W energy consumption. On the right is the new ASIC chip. By adding small components such as connectors, it will provide a three-antenna input equivalent to 12 40MHz channels and consume only 1W of energy. NASA’s 2017 SMD Technology Highlights Report says the team is developing a local oscillator based on a terahertz quantum cascade laser pointer (THz QCL) capable of pumping out a seven-element heterodyne receiver array. These local oscillators must emit single-frequency radiation of good spectral purity (4. The narrow line width of 7 terahertz is less than 1MHz,), and the single-frequency radiation can only be realized through the Distributed FeedBack (DFB) grating structure. So the team looked at three different DFB structures for potential applications in receivers and chose the best one: a one-way beam mode with a high power output level (the beam only radiates forward).