“We are looking to broaden the frequency range of operation while being compatible with current integrated photonic platforms, which inherently allows for device miniaturization,” Onuma said. The design will eliminate the need for multiple antennas and electro-optic modulators in broadband applications. While the technology isn’t connected to a particular mission, the design allows for flexible integration with low-power PICs, Onuma said. Developing smaller, faster, and more cost-effective technology will optimize mission costs across the board. “Radiometers, for example, that observe the microwave range of the electromagnetic spectrum are essential for profiling atmospheric constituents of planetary bodies for molecules like water,” Onuma said. Remote sensing engineers typically optimize their instruments’ antennas and front-end electronics circuits for the specific frequency band of scien-
tific interest, Onuma said. This means an instrument may need multiple electro-optic modulators and signal processors to accommodate different frequency bands. Consequently, each additional component results in an increase in heat generation, size, weight and power demands on a spacecraft. Having a single component that can receive and modulate broadband frequencies of interest enables a wider collection of scientific data. Shrinking these critical components will allow future missions to operate at the same, if not better, capacity while meeting the size, weight and power demands of small satellite platforms, Onuma said. “Other applications include software-defined radios and broadband wireless communications for terrestrial and space applications,” he said. v CONTACT Eleanya.E.Onuma@nasa.gov or 301.286.1157
Ultrafast Lasers Could Increase Accuracy of Mass Spectrometry Researchers at Goddard believe lasers that can pulse as quickly as one quadrillionth of a second could considerably improve the science of mass spectrometry by providing more accurate readings. “The femtosecond laser has the advantage that you can achieve high peak power but the pulse width is so short, you don’t actually heat up your materials,” said Dr. Anthony Yu, co-investigator on this project. Mass spectrometer technology requires a material to be disintegrated into atom-sized particles, which are then funneled between two magnets that sort the atoms by weight. Where the atoms hit on the detector can reveal their exact mass and therefore their specific element. Yu is part of a Goddard engineering team led by Elisavet Troupaki that, collaborating with Goddard scientists led by Dr. Andrej Grubisic, is researching super-fast lasers that can precisely disassemble atoms from a solid material without heating or burning them. This will improve the accuracy of mass spectrometers. An optimal power must be reached in order to properly break down materials, Yu said. To increase power in a laser you can increase the energy of the laser or shorten the laser pulse. Peak power www.nasa.gov/gsfctechnology
and pulse width – or length of time – are inversely proportional, meaning as one of the two variables decrease, the other increases. Studies are also being completed using nanosecond lasers, which are powerful, but do not allow for accurate spectrometry uses. “When it goes into the nanosecond regime, although it sounds very short already, it is heating the material,” said Goddard engineer Steven Li. Heating can alter the material’s properties and reduce the precision of a cut, two things you do not want for mass spectrometry. Not only does the femtosecond laser’s extremely short duration ensure that the materials won’t be heated, but the shorter pulse width also allows for a cleaner, more precise cut. A femtosecond laser has a pulse duration of 10-15, or one quadrillionth of a second, compared to the 10-9, or one billionth of a second, for a nanosecond laser. “This high-powered, extremely fast laser requires specific materials in the design and construction, and optical fiber is currently the best for this application,” Li said. Optical fiber has a core width of a few
PAGE 15
cuttingedge • goddard’s emerging technologies
Volume 18 • Issue 1 • Fall 2021
