Remote laser detection requires laser beam propagation through often unfavorable real-world atmospheric conditions. Turbulence is one of the main factors causing the beam to get distorted and lose its integrity and has direct implications on our ability to detect spectroscopic signatures remotely. One method to suppress turbulence effects is the use of vortex beams which have a spiral phase structure and carry the Orbital Angular Momentum (OAM). Vortex beams are generally considered to be more robust against the turbulence effects compared to conventional Gaussian beams. However, the actual vortex beam performance in remote sensing is also heavily dependent on the exact mode of vortex beam family it belongs to. In this work, we simulate the propagation of beams to a distance of 100 meters under controlled turbulence and compared the performance of a conventional Gaussian beam to two different modes of vortex beams: Hypergeometric Gaussian (HyGG) and Laguerre Gaussian (LG) beams. Through detailed evaluation of the beam circularity as a quantitative metric for beam propagation under turbulence, we demonstrate that HyGG vortex beams exhibit improved resistance against turbulence when compared to conventional Gaussian beams and LG vortex beams. This work provides insights toward a more comprehensive understanding of how vortex beams benefit long-range remote detection and identifying new strategies for long propagation-range propagation of tailored laser beams.
Conventional systems exploiting dynamic control of spatiotemporal beams using spatial light modulators are limited in data rate and power density. These are not the only limits, since the desired spatial control should include a continuum of Orbital Angular Momentum so that fractional and integer OAM states are possible, as well as coherent combinations to realize complex power flows for interaction science in linear and nonlinear regimes. This talk will summarize recent progress based on the spatial and dynamic control of Higher Order Bessel Gaussian Beams that can be reconfigured at unprecedented rates and applicable for high power densities. Applications will include propagation through dynamic turbulence, beam control and nonlinear interactions exploiting a continuum of OAM states. Future perspectives will also be discussed for a number of applications relevant to Maritime sensing.
KEYWORDS: Amplifiers, Lithium, Solid state lasers, Laser applications, Current controlled current source, Laser beam propagation, Composites, Sensing systems
In this effort, we report on the preservation of the spatial mode quality as composite vortex beams propagate through a flashlamp pumped amplifier system. Because of the spatially asymmetric nature of the transient thermal lensing, a laser beam propagating through this type of amplifier will be distorted. This makes an ideal environment to assess the mode integrity of propagating composite vortex beams. We demonstrate that a 3-lobe composite vortex beam can propagate under extreme transient thermal lensing and maintain the mode structure through the amplification process. Even though the actual amplification wasn’t the main thrust of this effort, we demonstrate gain greater than a factor of 4 for two different seed energy levels. Since the flashlamp pumped system is an extreme case, this result shows the potential for using concentric vortex beams in high power amplifiers and could open up new applications in propagation and sensing.
Underwater optical communication has recently become the topic of much investigation as the demands for underwater data transmission have rapidly grown in recent years. The need for reliable, high-speed, secure underwater communication has turned increasingly to blue-light optical solutions. The blue-green visible wavelength window provides an attractive solution to the problem of underwater data transmission thanks to its low attenuation, where traditional RF solutions used in free-space communications collapse. Beginning with GaN laser diodes as the optical source, this work explores the encoding and transmission of digital data across underwater environments of varying turbidities. Given the challenges present in an underwater environment, such as the mechanical and optical turbulences that make proper alignment difficult to maintain, it is desirable to achieve extremely high data rates in order to allow the time window of alignment between the transmitter and receiver to be as small as possible. In this paper, work is done to increase underwater data rates through the use of orbital angular momentum. Results are shown for a range of data rates across a variety of channel types ranging in turbidity from that of a clear ocean to a dirty harbor.
Space division multiplexing of optical beams has recently been demonstrated for improving the bandwidth of optical communication links. This paper will explore the use of space division multiplexing utilizing blue lasers for potential undersea applications. Experimental results will be shown for optical vortices utilizing a range of charge numbers corresponding to various Orbital Angular Momentum states.
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