Astronomy and Space Domain Awareness are limited by the size of available telescope optics, which in turn is related to the cost of exquisitely ground and polished primary mirrors. This creates the cost-size scaling “law” of optics: as the primary mirror gets larger, the cost grows polynomially, limiting mass manufacturing and proliferation. It is possible that liquid mirrors (LMs) may present a solution. When rotated at a constant angular velocity, fluid surfaces take the form of a light-focusing paraboloid with good optical quality. LMs therefore have the potential to break the cost-size scaling law and enable large-diameter optical surfaces. However, fundamental limitations remain. Traditional LMs can only point straight upward (to zenith) and are, therefore, limited in the imagery they can gather. Since the surface is a liquid, any out-of-plane movement disrupts the surface, causing spilling and rendering the imaging surface useless. Rotating machinery also adds complexity and are not scalable to very large mirror sizes. To address these limitations and enable low-cost, very-large-aperture telescopes, DARPA has launched its Zenith program. Zenith will investigate alternate LM designs and develop modeling tools, materials, surface shape controls, and structures to eliminate these limitations. The goal is to demonstrate a 2-m diameter liquid mirror telescope system (LMT) and a 1-m diameter segmented LM that require no liquid motion (rotation) to operate. Achieving Zenith goals will require unique approaches to maintaining good optical quality of a liquid surface in real time during slew and while tilted from the zenith axis. Software and simulation tools specific to liquid mirror performance modeling will be released to the astronomical community as an open-source repository at the conclusion of Phase I of the Zenith program.
Quantum walks (QWs) have emerged from fundamental research to be one of key processes in quantum information technology including quantum computing and quantum communication. In this paper, we present results of our numerical investigation of quantum walks (QWs) in different types of 2D arrays of waveguides. We show (i) the localized QWs in quasiperiodic arrays based on Fibonacci sequences are highly controllable due to the deterministically disordered nature of quasiperiodic photonic lattices, (ii) 2D arrays of waveguides can also be used as platforms to realize important effects for special applications such as exponential speedup in quantum search and quantum topology photonics and finally, (iii) results of multiple photons QWs in 2D programable directional couplers can be useful for designing quantum photonics gates.
Visible lasers with high pulse energy and high repetition rate are required for several important applications such as high-precision material processing and adaptive optics. Fiber lasers are unable to produce high pulse energy due to mode size limitation. In this paper, we will present results of a Q-switched rotary disk laser that produces 7.5 mJ pulses at 515 nm at 7 kHz repetition rate. The peak power of the green laser is 350 kW. Due to the absence of aberrations in a rotary disk laser, the beam quality is measured to be diffraction limited.
This paper gives expressions to calculate the fraction of power, fPIB, from a given multimode
gaussian laser beam that can be deposited within a bucket of radius, rT, on a target at a range,
zT, using a focusing optic of diameter, Df. We relate the power in the bucket, fPIB, to the M2
parameter, both of which can be experimentally measured. In this paper, we have also
presented relationships between these two parameters and BQ and Strehl, which have not been
unambiguously defined for a multimode laser beam in the literature. We propose fPIB and M2
to be used as standard design parameters instead of BQ and Strehl for laser-target interaction
tests with multimode laser beams from stable resonators.
In this paper, I present the design of a dispersive delay generator that is capable of producing 1 ns per
1 nm dispersive delay in a compact footprint. The path length delay produced by a grating and free space
is amplified by introduction of a total internal reflection surface operating at an angle of incidence near
the critical angle. Both positive and negative amplification may be realized in this technique by changing
the orientation of the angular dispersion amplifier optic. The device is not wavelength sensitive and it
uses bulk optics, which can handle high average power and high peak power. Because this method
produces significant pulse stretching for a given pulse bandwidth, it may lead to higher peak power laser
sources in the future. This delay generator has applications in pulse compressor, pulse stretcher or pulse
shaper in chirped pulse amplification and high-resolution time gated spectroscopy. The delay generator
can also be fabricated on silicon wafers for photonics integrated circuits.
In this paper, I will present the design analysis of a novel concept that may be used to generate a
diffraction-limited beam from an aperture so that as much as 450 kW of laser power can be efficiently
deposited on a diffraction-limited spot at a range. The laser beam will be comprised of many closely
spaced wavelength channels as in a DWDM. The technique relies on the ability of an angular dispersion
amplifier to multiplex a large number of high power narrow frequency lasers, wavelengths of which may
be as close as 0.4 nm.
KEYWORDS: Disk lasers, Solid state lasers, Resonators, Oscillators, Laser resonators, High power lasers, Laser development, Fiber lasers, Optical amplifiers, Diffraction
In this paper, I present quantitative designs of 25-kW and 100-kW laser oscillators containing a
number of Yb-ceramic YAG rotary disk laser generators. A design of an unstable resonator for the 100-
kW laser is also presented. The design is modular, with identical Yb-YAG rotary disk laser generators
stacked in series in a laser oscillator. Each rotary disk laser generator is identically pumped and cooled.
The calculations for one design example shows that with a 10-disk laser oscillator, 100-kW of laser power
may be extracted from an unstable resonator of magnification 3 at 46% optical efficiency and 53% slope
efficiency. Assuming 60% efficient laser diodes will be possible in the near future, the 100-kW rotary
disk laser design will require 367 kW of electrical power to produce 65 kW of power in a far-field bucket
of angular radius 1.5 λ/D.
Rotary disk laser technology enables high-power nonlinear optics and laser machining. Due to the
wavelength dependence of laser-material interaction, the ability to scale laser power across the spectrum is
always in great demand in laser processing of materials. Rotary disk laser technology has enabled high-power
nonlinear optics by being able to produce in excess of 200 W in single-mode Q-switched laser power
at 1 micron. This breakthrough has led to the power scaling of single-mode visible lasers at 515 nm to 88 W
and single-mode UV lasers at 343 nm to 53 W which have set power performance record at their respective
wavelengths. In this paper, we will present the results of the rotary disk laser sources in the UV, the visible
and the infrared. We will also present record-breaking results in dicing and scribing of silicon, single crystal
sapphire and PCBs, and in hole drilling of stainless steel.
Rotary disk laser has a very efficient thermal management approach that uses physical motion
of the gain medium in a diode-pumped solid state laser. The benefits of rotary disk lasers over
conventional bulk solid state lasers are high efficiency, power scalability and high peak power
pulsed operation in a single-mode output beam. We have generated 72.8 W of TEM00 Qswitched
output power at 50% slope efficiency in a crystalline Yb-YAG rotary disk laser.
In this paper, we will present recent results from the first commercially available rotary disk laser. Rotary disk laser concept introduces physical motion as a new control element in solid state laser designs. Rotary disk lasers have the potential of producing much higher power in single-mode operation than other types of bulk solid state lasers. Rotary disk lasers also have the potential of generating much higher energy pulses than fiber lasers. The Nd-YAG rotary disk laser produced 30.8 W of output power in a single mode at 32.4% optical efficiency. In a preliminary test, 81.9 W was obtained from a single mode Yb-YAG rotary disk laser.
KEYWORDS: Space telescopes, Telescopes, Mirrors, James Webb Space Telescope, Space robots, Optical instrument design, Robotics, Mirror structures, Astronomical imaging, Sensors
We will present a new approach to enable very large aperture telescopes in space. The approach is to autonomously assemble a segmented filled aperture telescope in space using components which may be launched into orbit using multiple launches. Autonomous assembly is a technology that can break the 10 m barrier in space optics imposed by launch vehicle limitations. The autonomously assembled space telescope (AAST) will follow the lead of Hubble telescope which uses monolithic optics, and JWST, which will implement deployable optics. An autonomously assembled space telescope of greater than 10 m diameter can significantly enhance the resolution and detection limit for imaging and space science, as well as enable formation of cost effective telescope constellations in space.
in this paper, we have reviewed the design principles and numerical formalisms applicable to push the average power limits of state-of-the-art solid-media lasers from typically 1 kilowatt to hundreds of kilowatt. Several device architectures are considered, taking into account utilization of off-the-shelf technology, and inclusion of realistic values of propagation loss. We demonstrate that once the beam propagation problem is addressed properly, laser devices employing solid-media are capable of producing 100 kW to 1 MW of average output power in cw operation at 6 to 12% wall plug efficiency. This will open up applications for solid-media lasers where gaseous and chemical lasers are currently used.
Intensity versus length experiments showed some exponentiation in Ni-like Nb at 204 angstroms, at pump energies of 1 to 2 Joules per pulse of 1 (mu) pump radiation. The largest total gain observed in these experiments is about (alpha) L approximately equals 3 as determined by a Linford fit. Streak camera results indicate that emission at 204 angstroms can persist for u to a nanosecond. More recent experiments indicate that the pump pulse width was variable during this campaign, and that the pump energy calibration was imprecise. Ni-like Nb appears to require on the order of 1013 watts/cm2 to drive gain, and we plan to increase our ump intensity to improve total gain.
A small-scale X-ray laser system for operations near 191 A at a repetition rate of 6 ppm is being developed on the basis of the Ni-like collision excitation scheme of Maxon et al. (1986). Based on the idea of Hagelstein (1988), an attempt is made to use low-Z material (instead of high-Z materials commonly used in collisional excitation schemes), which is to be pumped with a series of short pulses rather than with one long pulse. It is predicted that favorable density and temperature conditions will be present after a few initial pulses to generate gain on the order of 5-10/cm.
The development of a pump laser for x-ray lasers that operate at wavelengths longer than 1 (mu) would permit the attainment of higher electron temperatures for a given pump intensity. Such a system would be of interest for electron collisional schemes at low Z, and would have the potential to improve the overall system efficiency. An initial design for an optical parametric oscillator that would down-convert 1 (mu) radiation to 2 (mu) is presented.
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