26 research outputs found
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Centimeter-scale Optical Reference Cavities with Microfabricated Mirrors
The best performance from compact, portable, and repeatably manufactured electromagnetic (EM) oscillators has for decades been built upon crystalline quartz resonators operating at radio frequencies. Such a source of frequency-stable EM waves has enabled a wide-range of applications of significant technical and societal benefit, such as navigation and communication systems, distributed sensing, geodesy, and fundamental physics. However, meeting demands for increased measurement sensitivity requires pushing beyond a fractional frequency stability of 10-13, typical of the best ovenized quartz. To date, such performance has been available in the microwave domain only with the use of complex cryogenic systems, or in the optical domain at the expense of larger volume and weight. In either case, the size, weight, and power of state-of-the-art EM oscillators has relegated their use to laboratory experiments. Here we demonstrate the validity of manufacturable, compact Fabry-Pérot references that improve upon all other centimeter-scale oscillators by more than a factor of ten, including those based on solid-state optical resonators as well as quartz. In one specific implementation, we show an 8 mL bonded assembly containing 3 vacuum-gap Fabry-Perot optical cavities with mirrors lithographically fabricated on a single substrate, each with optical quality factor exceeding 10 billion. A laser stabilized to one of the cavities exhibits thermal noise-limited phase noise for offset frequencies ranging from 1 Hz to nearly 1 kHz, and fractional frequency stability of 7x10-15 at 1 second. In a second implementation, we show a temperature-insensitive 2 mL cavity, designed to operate a strontium lattice optical atomic clock and housed in an alignment-free, portable enclosure. With fractional instability of 1x10-14, this second cavity represents a major advance in portable compact frequency references, pertinent to myriad field-based experiments.</p
Compact, Portable, Thermal-Noise-Limited Optical Cavity with Low Acceleration Sensitivity
We develop and demonstrate a compact (less than mL) portable
Fabry-P\'{e}rot optical reference cavity. A laser locked to the cavity is
thermal noise limited at fractional frequency stability.
Broadband feedback control with an electro-optic modulator enables near
thermal-noise-limited phase noise performance from Hz to kHz offset
frequencies. The additional low vibration, temperature, and holding force
sensitivity of our design makes it well suited for out-of-the-lab applications
such as optically derived low noise microwave generation, compact and mobile
optical atomic clocks, and environmental sensing through deployed fiber
networks.Comment: 12 pages, 6 figure
Sustainable Human Presence on the Moon using In Situ Resources
New capabilities, technologies and infrastructure must be developed to enable a sustained human presence on the moon and beyond. The key to having this permanent presence is the utilization of in situ resources. To this end, NASA is investigating how in situ resources can be utilized to improve mission success by reducing up-mass, improving safety, reducing risk, and bringing down costs for the overall mission. To ensure that this capability is available when needed, technology development is required now. NASA/Marshall Space Flight Center (MSFC) is supporting this endeavor, along with other NASA centers, by exploring how lunar regolith can be mined for uses such as construction, life support, propulsion, power, and fabrication. Efforts at MSFC include development of lunar regolith simulant for hardware testing and development, extraction of oxygen and other materials from the lunar regolith, production of parts and tools on the moon from local materials or from provisioned feedstocks, and capabilities to show that produced parts are "ready for use". This paper discusses the lunar regolith, how the regolith is being replicated in the development of simulants and possible uses of the regolith
Chip-Based Laser with 1 Hertz Integrated Linewidth
Lasers with hertz-level linewidths on timescales up to seconds are critical
for precision metrology, timekeeping, and manipulation of quantum systems. Such
frequency stability typically relies on bulk-optic lasers and reference
cavities, where increased size is leveraged to improve noise performance, but
with the trade-off of cost, hand assembly, and limited application
environments. On the other hand, planar waveguide lasers and cavities exploit
the benefits of CMOS scalability but are fundamentally limited from achieving
hertz-level linewidths at longer times by stochastic noise and thermal
sensitivity inherent to the waveguide medium. These physical limits have
inhibited the development of compact laser systems with frequency noise
required for portable optical clocks that have performance well beyond
conventional microwave counterparts. In this work, we break this paradigm to
demonstrate a compact, high-coherence laser system at 1548 nm with a 1 s
integrated linewidth of 1.1 Hz and fractional frequency instability less than
10 from 1 ms to 1 s. The frequency noise at 1 Hz offset is suppressed
by 11 orders of magnitude from that of the free-running diode laser down to the
cavity thermal noise limit near 1 Hz/Hz, decreasing to 10 Hz/Hz
at 4 kHz offset. This low noise performance leverages wafer-scale integrated
lasers together with an 8 mL vacuum-gap cavity that employs micro-fabricated
mirrors with sub-angstrom roughness to yield an optical of 11.8 billion.
Significantly, all the critical components are lithographically defined on
planar substrates and hold the potential for parallel high-volume
manufacturing. Consequently, this work provides an important advance towards
compact lasers with hertz-level linewidths for applications such as portable
optical clocks, low-noise RF photonic oscillators, and related communication
and navigation systems
Micro-fabricated mirrors with finesse exceeding one million
The Fabry–Perot resonator is one of the most widely used optical devices, enabling scientific and technological breakthroughs in diverse fields including cavity quantum electrodynamics, optical clocks, precision length metrology, and spectroscopy. Though resonator designs vary widely, all high-end applications benefit from mirrors with the lowest loss and highest finesse possible. Fabrication of the highest-finesse mirrors relies on centuries-old mechanical polishing techniques, which offer losses at the parts-per-million (ppm) level. However, no existing fabrication techniques are able to produce high-finesse resonators with the large range of mirror geometries needed for scalable quantum devices and next-generation compact atomic clocks. In this paper, we introduce a scalable approach to fabricate mirrors with ultrahigh finesse (≥106</p
Photonic chip-based low noise microwave oscillator
Numerous modern technologies are reliant on the low-phase noise and exquisite
timing stability of microwave signals. Substantial progress has been made in
the field of microwave photonics, whereby low noise microwave signals are
generated by the down-conversion of ultra-stable optical references using a
frequency comb. Such systems, however, are constructed with bulk or fiber
optics and are difficult to further reduce in size and power consumption. Our
work addresses this challenge by leveraging advances in integrated photonics to
demonstrate low-noise microwave generation via two-point optical frequency
division. Narrow linewidth self-injection locked integrated lasers are
stabilized to a miniature Fabry-P\'{e}rot cavity, and the frequency gap between
the lasers is divided with an efficient dark-soliton frequency comb. The
stabilized output of the microcomb is photodetected to produce a microwave
signal at 20 GHz with phase noise of -96 dBc/Hz at 100 Hz offset frequency that
decreases to -135 dBc/Hz at 10 kHz offset--values which are unprecedented for
an integrated photonic system. All photonic components can be heterogeneously
integrated on a single chip, providing a significant advance for the
application of photonics to high-precision navigation, communication and timing
systems
Low-noise microwave generation with an air-gap optical reference cavity
We demonstrate a high finesse, microfabricated mirror-based, air-gap cavity with volume less than 1 ml, constructed in an array, that can support low-noise microwave generation through optical frequency division. We use the air-gap cavity in conjunction with a 10 nm bandwidth mode-locked laser to generate low phase noise 10 GHz microwaves, exhibiting a phase noise of −95 and −142 dBc/Hz at 100 Hz and 10 kHz offset frequencies, respectively. This is accomplished using the 2-point lock optical frequency division method, where we exploit 40 dB common-mode rejection of two lasers separated by 1.29 THz and locked to the same air-gap cavity. If used with an octave spanning comb, the air-gap cavity is capable of supporting 10 GHz phase noise below −160 dBc/Hz at 10 kHz offset, a level significantly lower than electronic synthesizers. These results show how extremely small optical reference cavities, operated without the benefit of vacuum enclosures or thermal insulation, can, nonetheless, support state-of-the-art microwave phase noise in compact and portable systems
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Chip-based laser with 1-hertz integrated linewidth
Lasers with hertz linewidths at time scales of seconds are critical for metrology, timekeeping, and manipulation of quantum systems. Such frequency stability relies on bulk-optic lasers and reference cavities, where increased size is leveraged to reduce noise but with the trade-off of cost, hand assembly, and limited applications. Alternatively, planar waveguide-based lasers enjoy complementary metal-oxide semiconductor scalability yet are fundamentally limited from achieving hertz linewidths by stochastic noise and thermal sensitivity. In this work, we demonstrate a laser system with a 1-s linewidth of 1.1 Hz and fractional frequency instability below 10-14 to 1 s. This low-noise performance leverages integrated lasers together with an 8-ml vacuum-gap cavity using microfabricated mirrors. All critical components are lithographically defined on planar substrates, holding potential for high-volume manufacturing. Consequently, this work provides an important advance toward compact lasers with hertz linewidths for portable optical clocks, radio frequency photonic oscillators, and related communication and navigation systems