An official website of the United States government
The Arctic atmosphere and subauroral region are a natural laboratory for understanding plasma-neutral and dynamical coupling in the atmosphere and geospace. During geomagnetically active periods the auroral electrojet and auroral precipitation are overhead at the High-Frequency Active Auroral Research Program (HAARP) facility in Gakona, Alaska (62°N, 145°W) and facilitate active experiments. Iron resonance lidar systems are uniquely suited for these active investigations as naturally occurring iron layers extend from the upper mesosphere to the middle thermosphere (~70-150 km). A novel lidar system has been demonstrated at the German Aerospace Center using an Nd:YAG laser that operated at a minor line at 1116 nm and was tripled to the iron resonance line at 372 nm. This prototype laser was fully solid-state without liquid dyes or flashlamps and with diode pumping. We are developing a lidar system based on this prototype system that can operate robustly at the remote location of HAARP. We will employ a diode-pumped Nd:YAG laser with second and third harmonic generation. The laser will be injection-seeded by a tunable diode laser allowing the laser to frequency scan the iron line. The laser pulse spectra will be recorded on a shot-by-shot basis using an etalon imaging system with a spectral reference. The lidar system is will operate at 372 nm, with a pulse repetition rate of 100 pps, a pulse energy of 30 mJ, and a 0.9-m diameter telescope. We present the system specifications and the expected performance of the system.
more »
« less
Development of an All-Solid-State Iron Resonance Temperature Lidar
The coupling between the neutral and ionized atmosphere is important to improve our understanding of the dynamics of the upper atmosphere and thus improving the prediction of space weather. The Arctic atmosphere is a natural laboratory for understanding these processes. The High-frequency Active Auroral Research Program (HAARP) facility located in Gakona Alaska hosts many scientific instruments that can be used for active experiments. An all-solid state Iron Resonance Temperature Lidar system is under development to be deployed at HAARP to enrich the capability of the HAARP facility. We present recent developments of this lidar system. Progress has been made on the development of the transmitter, and the etalon-based laser frequency monitoring system. We are modifying a commercial Nd:YAG laser to operate at 1116 nm. We have achieved broadband lasing at 1116 nm with 1mJ at 100 Hz in long-pulse mode. The 1116 nm laser will be Q-switched and injection seeded to yield narrowband high power emission. The light will then be tripled to 372 nm and serve as the lidar transmitter. Using a frequency-lock Rb laser, we demonstrate accurate monitoring of the laser’s frequency differences when locked to different Doppler free features with errors <1 MHz. This will support the measurement of temperature with this lidar.
more »
« less
- Award ID(s):
- 2048628
- PAR ID:
- 10580072
- Publisher / Repository:
- EPJ Web of Conferences
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
The Arctic atmosphere and subauroral region are a natural laboratory for understanding plasma-neutral and dynamical coupling in the atmosphere and geospace. During geomagnetically active periods the auroral electrojet and auroral precipitation are overhead at the High-Frequency Active Auroral Research Program (HAARP) facility in Gakona, Alaska (62°N, 145°W) and facilitate active experiments. Iron resonance lidar systems are uniquely suited for these active investigations as naturally occurring iron layers extend from the upper mesosphere to the middle thermosphere (~70-150 km). A novel lidar system has been demonstrated at the German Aerospace Center using an Nd:YAG laser that operated at a minor line at 1116 nm and was tripled to the iron resonance line at 372 nm. This prototype laser was fully solid-state without liquid dyes or flashlamps and with diode pumping. We are developing a lidar system based on this prototype system that can operate robustly at the remote location of HAARP. We will employ a diode-pumped Nd:YAG laser with second and third harmonic generation. The laser will be injection-seeded by a tunable diode laser allowing the laser to frequency scan the iron line. The laser pulse spectra will be recorded on a shot-by-shot basis using an etalon imaging system with a spectral reference. The lidar system is will operate at 372 nm, with a pulse repetition rate of 100 pps, a pulse energy of 30 mJ, and a 0.9-m diameter telescope. We present the system specifications and the expected performance of the system.more » « less
-
Abstract A spectrogram of Power Line Harmonic Radiation (PLHR) consists of a set of lines with frequency spacing corresponding exactly to 50 or 60 Hz. It is distinct from a spectrogram of Magnetospheric Line Radiation (MLR) where the lines are not equidistant and drift in frequency. PLHR and MLR propagate in the ionosphere and the magnetosphere and are recorded by ground experiments and satellites. If the source of PLHR is evident, the origin of the MLR is still under debate and the purpose of this paper is to understand how MLR lines are formed. The ELF waves triggered by High-frequency Active Auroral Research Program (HAARP) in the ionosphere are used to simulate lines (pulses of different lengths and different frequencies). Several receivers are utilized to survey the propagation of these pulses. The resulting waves are simultaneously recorded by ground-based experiments close to HAARP in Alaska, and by the low-altitude satellite DEMETER either above HAARP or its magnetically conjugate point. Six cases are presented which show that 2-hop echoes (pulses going back and forth in the magnetosphere) are very often observed. The pulses emitted by HAARP return in the Northern hemisphere with a time delay. A detailed spectral analysis shows that sidebands can be triggered and create elements with superposed frequency lines which drift in frequency during the propagation. These elements acting like quasi-periodic emissions are subjected to equatorial amplification and can trigger hooks and falling tones. At the end all these known physical processes lead to the formation of the observed MLR by HAARP pulses. It is shown that there is a tendency for the MLR frequencies of occurrence to be around 2 kHz although the exciting waves have been emitted at lower and higher frequencies. Graphical Abstractmore » « less
-
Traditionally, quantitative lidar techniques like differential absorption lidar (DIAL) and high-spectral-resolution lidar (HSRL) utilize high-power-aperture product designs, which partially compensates for the need to take discrete deriva-tives of noisy data in post-processing (for number density for DIAL and extinction for HSRL) and provides for high-performance measurements, i.e., higher resolu-tion, accuracy, or precision. Conversely, low-power-aperture product lidar designs are easier to make eye-safe, reliable, and cost-effective, which are important attributes for network development and field deployment. The atmospheric science community has expressed the need for high-quality, quantitative, robust, network deployable, and cost-effective sensors for a variety of applications such as improved numerical weather forecasting – in essence requiring the best of both worlds without the accompanying drawbacks. In response to this need, the National Center for Atmospheric Research and Montana State University have been developing the MicroPulse DIAL (MPD) architecture for thermodynamic profiling in the lower atmosphere. The MPD architecture takes advantage of the benefits of low-power, low-cost laser diodes, and fiber optics to achieve quantitative profiling leverag-ing narrowband filtering and efficient elastic scattering. A field-deployable MPD instrument capable of humidity, quantitative aerosol, and temperature profiling has recently been developed. This presentation will describe the current status of this thermodynamic profiler and the initial results from a recent field deployment. Emphasis will be given to the analysis of the temperature data including compar-isons to co-located radiosondes to describe current performance.more » « less
-
Abstract Frequency modulated continuous wave laser ranging (FMCW LiDAR) enables distance mapping with simultaneous position and velocity information, is immune to stray light, can achieve long range, operate in the eye-safe region of 1550 nm and achieve high sensitivity. Despite its advantages, it is compounded by the simultaneous requirement of both narrow linewidth low noise lasers that can be precisely chirped. While integrated silicon-based lasers, compatible with wafer scale manufacturing in large volumes at low cost, have experienced major advances and are now employed on a commercial scale in data centers, and impressive progress has led to integrated lasers with (ultra) narrow sub-100 Hz-level intrinsic linewidth based on optical feedback from photonic circuits, these lasers presently lack fast nonthermal tuning, i.e. frequency agility as required for coherent ranging. Here, we demonstrate a hybrid photonic integrated laser that exhibits very narrow intrinsic linewidth of 25 Hz while offering linear, hysteresis-free, and mode-hop-free-tuning beyond 1 GHz with up to megahertz actuation bandwidth constituting 1.6 × 1015Hz/s tuning speed. Our approach uses foundry-based technologies - ultralow-loss (1 dB/m) Si3N4photonic microresonators, combined with aluminium nitride (AlN) or lead zirconium titanate (PZT) microelectromechanical systems (MEMS) based stress-optic actuation. Electrically driven low-phase-noise lasing is attained by self-injection locking of an Indium Phosphide (InP) laser chip and only limited by fundamental thermo-refractive noise at mid-range offsets. By utilizing difference-drive and apodization of the photonic chip to suppress mechanical vibrations of the chip, a flat actuation response up to 10 MHz is achieved. We leverage this capability to demonstrate a compact coherent LiDAR engine that can generate up to 800 kHz FMCW triangular optical chirp signals, requiring neither any active linearization nor predistortion compensation, and perform a 10 m optical ranging experiment, with a resolution of 12.5 cm. Our results constitute a photonic integrated laser system for scenarios where high compactness, fast frequency actuation, and high spectral purity are required.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- The DOI is not currently available.
