Solar Pumped Lasers for Free Space Laser Communication

Zhao, Changming; Zhang, Haiyang; Guan, Zhe; Cai, Zitao; He, Dongxuan; Wang, Yongheng

doi:10.5220/0007569702680275

Cited by 4 publications

(2 citation statements)

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“…CO 2 lasers at 10.6 μm have efficiencies up to 10% while solar pumping of a Nd:Cr:YAG laser offers an efficiency of 35% (van den Donken, 2019). A solar pumped laser using a Fresnel lens concentrating light onto a conical quartz rod to a grooved Nd:YAG lasing rod has been demonstrated for free-space laser communications (Zhao et al, 2019). Free electron lasers (FEL) have efficiencies of 20% that may be further elevated if combined with solar pumping (Ellery, 2021e, 2022a with the advantage that our self-replication scheme includes the construction of thermionic vacuum tubes and motor-based magnetic components.…”

Section: Beamed Propulsionmentioning

confidence: 99%

Self-replicating probes are imminent – implications for SETI

Ellery

2022

International Journal of Astrobiology

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In the early 1980s, the Sagan-Tipler debate raged regarding the interpretation of the Fermi paradox but no clear winner emerged. Sagan favoured the existence of ETI on the basis of the Copernican principle and Tipler favoured the non-existence of ETI on the basis of the Occam's razor principle. Tipler's stance was an expansion of the similar but earlier Hart declaration. However, crucial to the Tipler argument was the role played by self-replicating interstellar robot probes. Any technologically capable species will develop self-replication technology as the most economical means of exploring space and the Galaxy as a whole with minimal investment. There is no evidence of such probes in our solar system including the asteroid belt, ergo, ETI do not exist. This is a powerful and cogent argument. Counter-arguments have been weak including Sagan's sociological explanations. We present a Copernican argument that ETI do not exist – humans are developing self-replication technology today. We are developing the ability to 3D print entire robotic machines from extraterrestrial resources including electric motors and electronics as part of a general in-situ resource utilization (ISRU) capability. We have 3D-printed electric motors which can be potentially leveraged from extraterrestrial material that should be available in every star system. From a similar range of materials, we have identified a means to 3D print neural network circuitry. From our industrial ecology, self-replicating machines and indeed universal constructors are feasible. We describe in some detail how a self-replicating interstellar spacecraft may be constricted from asteroidal resources. We describe technological signatures of the processing of asteroidal material (which is expected to be common to most star systems), and the excess production of certain types of clay and other detritus materials. Self-replication technology is under development and imminent – if humans are pursuing self-replication technology, then by the Copernican principle, so would any technologically savvy species elsewhere. There is no evidence that they have.

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Section: Beamed Propulsionmentioning

confidence: 99%

Self-replicating probes are imminent – implications for SETI

Ellery

2022

International Journal of Astrobiology

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“…to their advantages of good heat dissipation, high efficiency, and good stability [6,7]. Solar-pumped fiber lasers (SPFLs) have shown attractive prospects in the fields of military, aerospace, material processing, and space communications [8,9].…”

Section: Introductionmentioning

confidence: 99%

Solar side-pumped Nd-doped fiber laser based on a doughnut-shaped hollow reflector

Zhu,

Liu,

Lan

et al. 2023

Laser Phys. Lett.

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A high-power solar side-pumped Nd-doped fiber laser based on a doughnut-shaped hollow reflector (DHR) is proposed. The primary concentrator consists of twelve off-axis parabolic mirrors. The DHR coupled with an array of three-dimensional compound parabolic concentrators (3D-CPCs) functions as the secondary concentrator, inside which many cycles of Nd-doped fiber is coiled. After being reflected by the off-axis parabolic mirrors, the sunlight is launched into the DHR through the twelve 3D-CPCs, and experiences multiple-times reflection by the DHR, and finally is absorbed by the Nd-doped fiber for laser oscillation. Ray tracing shows that 173-W of solar power can be absorbed by the fiber. By solving the rate equations and power transmission equations, laser output power, slope efficiency and optical-to-optical conversion efficiency of 10.3 W, 6.12% and 5.94%, respectively, are realized. This kind of solar-pumped fiber laser thus offers a new route for achieving high-power solar-pumped laser sources.

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Brief History of Solar-Pumped Lasers

Almeida

2023

Solar-Pumped Lasers

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Solar Pumped Lasers for Free Space Laser Communication

Cited by 4 publications

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Self-replicating probes are imminent – implications for SETI

Self-replicating probes are imminent – implications for SETI

Solar side-pumped Nd-doped fiber laser based on a doughnut-shaped hollow reflector

Brief History of Solar-Pumped Lasers

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