This PDF file contains the front matter associated with SPIE Proceedings Volume 10770, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

The ocean surface has considerable impact on air-to-sea (or sea-to-air) imaging, lidar scanning, and optical communication. This surface is rarely smooth, of course, especially in the littoral region (due to a variety of impacts, from wind to ship wakes, etc.). Most current and previous methods for addressing this roughness and its impact on optical propagation are either fully statistical, totally theoretical, or are “mixed methods” based on a combination of statistical models and parametric-based physical models (our preferred approach). To better understand the statistical nature of the sea surface, experiments were performed in a 50 foot long wave tank capable of not only producing large scale, multi-frequency waves, but also wind driven waves over a range of velocities. High speed imaging (i.e., Photron FASTCAM Mini series^(R)) of laser beam projection as well as spatial distribution of surface glint, scanned laser velocimetry measurements of the surface, and deflection statistics of the doubled Nd:YAG (532 nm) beam will all be utilized to produce statistical models of sea surface perturbations under various wind loads and larger scale wave forcing. These data, combined with our mixed model, will help us to measure, analyze, and understand the shape of the sea surface and assess its subsequent impact on optical propagation and specifically on aerial to underwater FSO communication links.

Reliable communication between aerial and undersea vehicles is a challenging issue because radio frequency signals are attenuated drastically in sea water while acoustic waves are not preferable in terrestrial links. Located in the transmittance windows of both sea water and the atmosphere, blue-green laser based free-space optical communication systems are capable of providing high speed, low latency data links for this very scenario. Apart from the absorbing and scattering attenuations in the air-water channel, another limiting factor impacting efficient laser beam propagation is the turbulence induced intensity fluctuations. Pure attenuation in sea water restricts the laser communication distance to ~100 meters, which will further reduce to ~10 meters in the presence of oceanic turbulence. Meanwhile, atmospheric turbulence can also substantially degrade the beam quality if the aerial vehicle is at high altitude. In this study, we focus our effort on the turbulence effects on beam propagation in the air-water two-stage links, not taking into account media attenuation or water surface distortions. Considering the complexity of the depth dependence of salinity and temperature in sea water and the altitude dependence of air refractive-index structure constant, we use numerical methods to simulate the beam propagation through the two-stage turbulence channel, which is modeled by discrete phase screens generated with parameterized atmospheric and oceanic turbulence power spectrums. On that basis, beam spread, area scintillation and SNR penalty at the receiver end are analyzed for the uplink as well as the downlink transmission.

Security is an increasingly important issue in modern communication. We propose a concept for secure detection of vortex beams in free space optics (FSO). The transmitted signal is composed of a Gaussian beam together with a low powered vortex beam. For each vortex mode, we select the detectors with the maximum received power for the particular signal, depending on the spatial distribution probability of the signal beam. Eavesdroppers have no way of knowing which patterns are relevant for the transmitted signal. We perform a numerical calculation for maximal signal detection and security. Applications include l free space communication.

Over the last few years, there has been an exponential increase in the amount of communication network traffic, where the data center (DC) is a major building block of this network. However current DCs face various problems in the light of current demands, such as high power consumption, low scalability and low flexibility. It is necessary to build a new high speed data center which could support this exponential growth. One of the technologies that could scale up the performance of the data center is free space optical (FSO) communication. FSO communication could provide an adaptive, flexible and dynamic network that could meet the performance requirements of future DCs. However, no one has characterized the optical communication channel in DC. In DC there is an HVAC system that causes non-homogeneous changes in temperature and air velocity that can affect the performance of the optical signal. In this work, we demonstrate that by using deep learning algorithms for channel estimation and signal detection, without knowledge of the channel model, we can improve the signal detection and increase the performance of the optical communication in DC environment.

Due to expected capacity bottlenecks of exploited microwave technologies, feeder links for data relay or broadband access systems will require the implementation of high capacity optical communication links between space and ground. In this context, it is necessary a detailed investigation of the optical technologies and techniques that could enable the transmission of high data rates at optical frequencies through the Earth’s atmosphere, with regard to all kinds of atmospheric phenomena. In particular, the adverse effects of atmospheric turbulence fading are of special relevance to optical communication systems for ground-to-space uplink applications. Although previous studies and experiments have demonstrated the feasibility of such optical links at low data rate, research is still needed to identify technical solutions and strategies adapted to the specific constraints imposed to these high-speed links in order to ensure the required level of performance. Against this background, various test benches have been developed in order to characterize different modulation and detection techniques for optical communication systems prior to be incorporated in the conceptual design of future 1-Tb/s ground-space optical links. The expected performances of such an experimental demonstration are derived based on simulation models taking into account atmospheric turbulence effects, in order to prove the feasibility of reliable ground-space high date rate optical communication links. Our first simulation studies, considering On-Off Keying (OOK) and Differential Phase Shift Keying (DPSK) modulations, have allowed us to understand the complexity of the link and to optimize both the transmitter and the receiver to achieve acceptable performance levels.

In this report, the characteristics of non-line-of-sight (NLOS) ultraviolet (UV) overwater communication channels which includes scattering and turbulence effects are modeled using Monte Carlo multiple scattering simulation. The overwater field experimental measurements of turbulence effect and path loss at the distances of up to 1700 meters were reported and analyzed by considering key parameters such as communication distance, transceiver angles, water surface reflection index, along with airborne humidity, and temperature. These channel modeling and experimental results will serve as the foundation for further study of the NLOS UV overwater communication system in shore-to-shore (STS), shore-to-vessel (STV), and vessel-to-vessel (VTV) communication link configurations.

The information networks of the future will consist of an all-optical core, with wireless access technologies wherever possible. The fibre networks are extending their reach rapidly, and will further extend to individual spaces within homes and office buildings. The data traffic on networks and the demand for wireless services are also growing exponentially and the nature of services is also evolving with rapid increase in the number of devices. A new generation of 3D displays, with the ability to create Virtual Reality (VR) environments, is being launched. VR technology places significant demands on bandwidth, latency, positioning and mobility. One challenge addressed by our European collaborative project WORTECS is the development of an optical wireless system able to deliver ultra-high throughput (up to Tbps). The first demonstrator focuses on a high density network that can provide > 1 Gbps per user with multi user, but has the potential to provide Tbps per indoor environment. The second demonstrator focuses on ultra-high data rate links with a novel fibre-optical wireless-fibre approach to create Tbps capable links. VR is targeted as a demanding application, however, other applications include wireless data centers and aircraft cabins. In this paper, after introduction on the demand for wireless Terabit/s communication, we will focus on VR use case and the need for multi-Gigabit/s data rates. Then we will present the challenges for the project and propose new optical wireless system architecture and system engineering associated to new approach in space and frequency diversity with OFDM and adaptive bit rate for VR.

We are presenting a new method for optical Two-Way Time Transfer based on the Single Photon Counting approach. The method can be used in parallel with standard fiber or free-air media bi-directional optical communication link without causing any interference using any type of optical transmitters including standard Small Form-Factor Pluggable laser modules. Additionally, as only an average signal of -100 dBm or less is required, it can also be performed on very long distances of over 500 km within optical fibers without any amplification, but in the latter case limited to cases when the data communication is not necessary due to high attenuation. The method was tested either with simulated and real data sets measured in our laboratory and it has proven its reliability and precision in the order of 1 ps or less. Thanks to the photon counting approach the systematic errors are minimized to ps level. The aim of our further research is to test the method on real communication data links, either in optical fiber or free-air media.

Effective performance of laser systems intended for power delivery on a distant object requires an adaptive optics system to correct the laser beam distortions caused by atmospheric perturbations along the propagation path. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and decline of the power density on the target. Adaptive optics methods are used to compensate these negative effects. In its turn, operation of the Adaptive Optics System (AOS) requires a reference wave that can be generated by the beacon on the target. This report discusses the requirements to the beacon that can support optimal correction of the wavefront. Post-processing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront — data essential to control the adaptive optics module of a high-power laser system.

The effect of laser noise on the atmospheric propagation of high-power CW lasers and high-intensity short pulse lasers in dispersive and nonlinear media is studied. We consider the coupling of laser intensity noise and phase noise to the spatial and temporal evolution of laser radiation. High-power CW laser systems have relatively large fractional levels of intensity noise and frequency noise. We show that laser noise can have important effects on the propagation of high-power as well as high-intensity lasers in a dispersive and nonlinear medium such as air. A paraxial wave equation, containing dispersion and nonlinear effects, is expanded in terms of fluctuations in the intensity and phase. Longitudinal and transverse intensity noise and frequency noise are considered. The laser propagation model includes group velocity dispersion, Kerr, delayed Raman response, and optical self-steepening effects. A set of coupled linearized equations are derived for the evolution of the laser intensity and frequency fluctuations. In certain limits these equations can be solved analytically. We find, for example, that in a dispersive medium, frequency noise can couple to and induce intensity noise, and vice versa. At high intensities the Kerr effect can reduce this intensity noise. In addition, significant spectral modification can occur if the initial intensity noise level is sufficiently high. Finally, our model is used to study the transverse and longitudinal modulational instabilities. We also present atmospheric propagation examples of the spatial and temporal evolution of intensity and frequency fluctuations due to noise for laser wavelengths of 0.85 μm , 1 μm , and 10.6 μm .

Innovative technologies are needed to support and augment the development of various types of deformable mirrors (DM), such as Micro Electro Mechanical Systems (MEMS), segmented, bimorph and membrane types that are currently used in adaptive-optic (AO) systems. The paper discusses the results of initial studies that, could, potentially, be employed for full characterization of the dynamic behavior of adaptive optics mirrors. The experimental data were obtained from a typical bimorph mirror using both, a Shack-Hartman wavefront sensor (SHWFS) and an Imaging Laser Doppler Vibrometer (ILDV) developed exclusively by AS&T Inc. These two sensors were employed for quantitative measurement of both the spatial and temporal dynamics of the DM under broadband excitation via the piezo electric drive elements. The need to characterize the spatial and temporal dynamic response of current and future DM mirror designs is essential for optimizing their performance to a level adequate for high bandwidth AO systems, such as those employed for real-time compensation of wavefront perturbations.

Refraction effects can alter the appearance of an object near the horizon, resulting in sometimes severely distorted images of the object. The amount of distortion is determined by the curved trajectory that light rays follow through the atmosphere. Variations in the index of refraction, due to among others variations in the temperature of the atmosphere, are responsible for this curving of light rays. There are several models that can be used for to calculate the curvature of the light rays. Lehn has developed a simple model that traces light rays through a refracting atmosphere. The atmosphere is represented by spherical layers in which the temperature is taken constant. The intersections of the light ray and the boundaries are calculated in terms of the temperature and pressure of the atmosphere in this layer.

It is understood that atmospheric turbulence results in fluctuations in the received power of an electro-optical (EO) link, a phenomenon known as optical scintillation. The atmospheric variable relevant to optical scintillation is the structure function parameter (C_n²) which can be quantified through optical scintillation measurements or derived from measurements of high-rate sampled atmospheric turbulence, especially the temperature perturbations. In addition to this (C_n²) can be estimated using models, some of which are based on surface layer similarity theory. However, the near shore marine atmospheric surface layer (MASL) provides an optically heterogeneous and complex turbulent environment that can be difficult to model accurately. A better understanding of the characteristics of near shore surface layer scintillation will provide increased exploitation of the environment by current and future EO systems operating in littoral regions. In an effort to better determine the scintillation effects in the MASL, observations were taken during the 26-day Couple Air-Sea Processes and Electromagnetic ducting Research West coast (CASPER-West) field campaign in September - October 2017 off the coast of Pt Mugu, CA.

In this paper, we introduce the CASPER-West EO component to include a description of the operating area, major platforms and major instruments relevant to EO measurements, and sampling strategy. We show comparisons of the derived (C_n²) from scalar perturbation measurements, bulk model parameterization, and from concurrent scintillation measurements between the R/V Sally Ride and R/P FLIP. Slant path optical links between a remotely piloted hexa-copter and the R/P FLIP were also available. Both stable and unstable thermal stratifications of the MASL were encountered throughout the campaign and we will discuss the observed differences between the experiment and those from current similarity theories in these different stability conditions.

We present an experimental evaluation of a multi-aperture laser transmissometer system which profiles long-term laser beam statistics over long paths. While the system was originally designed to measure the aerosol extinction rate, the beam profiling capabilities of the transmissometer system also allows experimental observations of Gaussian beam statistics in weak and strong turbulence. Additionally, measurement of long-term beam spread at the receiver allows the system to estimate a path-averaged C_n², including in strong turbulence regimes where scintillometers experience saturation effects. Additionally, a phase-frequency correlation technique for synchronizing with transmitter ON/OFF modulation in the presence of background ambient light is presented. In application, our ruggedized and weather resistant laser transmissometer system has significant advantages for the measurement and study of aerosol concentration, absorption, scattering, and turbulence properties over multi-kilometer paths, which are crucial for directed energy systems, ground-level free-space optical communication systems, environmental monitoring, and weather forecasting.

Recently, the number of optical systems that operate along near horizontal paths within a few meters of the ground has increased rapidly. Examples are LIDAR or optical sensors imbedded in a vehicle, long range surveillance or optical communication systems, a LIFI network, new weather monitoring stations, as well as directed energy systems for defense purposes. Near ground turbulence distortion for optical waves used in those systems cannot be well described by conventional turbulence and beam propagation theory. Phenomena such as anisotropy, micro mirage effects, a temporal negative relation between diurnal dips and altitude, and condensation induced measurement errors are frequently involved. As a result, there is a high risk of defective designs or even failures in those optical systems if the near ground turbulence effects are not well considered. To illustrate such risk, we make C_n² measurements by different approaches and cross compare them with associated working principles. By demonstrating the reasons for mismatched C_n² results, we point out a few guidelines regarding how to use the general anisotropy theorem and the risk of ignoring it. Our conclusions can be further supported by an advanced plenoptic sensor that provides continuous wavefront data.

Researchers from the University of Central Florida recently carried out a series of measurements over a concrete runway and a grass range using a 632.8 nm Gaussian beam propagated for 100 or 125 m at a height of 2 m. Mean intensity and scintillation index contours varied significantly throughout these measurements in ways that corresponded to more than simple isotropy or anisotropy of optical turbulence. A simple theory is developed to show the effect of a nonlinear index of refraction gradient in addition to the possibility of anisotropic turbulence. Theoretical contours are compared to experimental results which seem to indicate the presence of a beam shaping phenomena near the ground in addition to anisotropy.

Ground to air temperature gradients drive the creation and evolution of optical turbulence in the atmospheric boundary layer. Ground composition is an important factor when observing and measuring the generated optical turbulence. Surface roughness and thermal characteristics influence the formation of optical turbulence eddies. The Space Shuttle Landing Facility (SLF) at The Kennedy Space Center offers a unique opportunity to measure the generation and evolution of these turbulent eddies, while also providing a temperature gradient “Step Function” after which turbulence evolution can be analyzed. We present the analysis of data collected on the SLF during May of 2018. Mobile towers instrumented with sonic anemometers are used to examine the statistics of turbulent eddies leaving the increased heat gradient of the runway. This data is compared to an optical scintillometer and other local weather station data. Point and path average C_n² data are calculated and attention is given to turbulence spectrum as a function of height above ground.

The propagation of light through an atmospheric optical channel is modified by scattering effects that include extinction, bulk refraction, and optical turbulence. For most paths exceeding 1 kilometer, the effects of the atmosphere can be substantial, changing the effectiveness and performance of many passive and active optical systems. An accurate assessment of the optical channel within the planetary boundary layer remains a difficult problem. We are interested in propagation paths from surface to several kilometers in height, over a path of 2 to 10 kilometers in length. The current model approach uses vertical profiles of extinction and turbulence intensity to provide the fundamental requirements for assessment of optical propagation effects. The central problem we address here is the fact many of the atmospheric profile models are parametric or regression models, and the model parameters are frequently determined by a set of meteorological conditions at a single near-surface point. It is apparent that very little of the complex physics within the interior of the propagation volume is reproduced. The top of the atmospheric boundary layer is a dynamic region, with a possibility of large changes in aerosol extinction and turbulence, and we will describe new efforts to utilize numerical weather prediction (NWP) and ground-based lidar to provide more accurate atmospheric profiles.

An accurate forecast of atmospheric turbulence is needed to characterize the performance of free-space electro-optical systems. Atmospheric turbulence physics is intricate and stochastic and relies on an assortment of assumptions, making modeling difficult to formulate in a rigorous first principles manner. Machine learning (ML) techniques have been shown to parameterize complex relationships in large datasets and are able to more accurately predict response variables than standard regression methods. This study applies machine learning techniques to develop a model that forecasts the refractive index structure parameter, 𝐶𝑛 2. Measurements of 𝐶𝑛 2 were obtained from a field experiment along with meteorological observations. Several machine learning models were created and compared to optical scintillometer output and current atmospheric turbulence models. The ML based models are shown to generate predictions of 𝐶𝑛 2 that are more highly correlated to observed 𝐶𝑛 2 than physics-based formulations.

Post-processing of light fields enables us to extract more information from a scene compared to traditional camera. Plenoptic cameras and camera arrays are two common methods for light-field capture. In fact, it has been long recognized that the two devices are in some ways equivalent. Practically though, light field capture via camera arrays results in poor angular sampling. Similarly, the plenoptic camera often suffers from relatively poor spatial sampling. In simulation, we can easily explore both constraints by simulating two-dimensional view point images and combining them into a four dimensional light field. In this work, we present a formalism for converting between equivalent plenoptic configurations and camera arrays. We use this approach to simulate a simple scene and explore the trade-offs in angular and spatial sampling in light-field capture.

Laser propagation through deep turbulence requires adaptive optic systems capable of correcting wavefront distortions with large phase shifts. The large phase shifts, can be overcome by using dual deformable mirrors in a woofer-tweeter configuration. In this configuration the woofer corrects low spatial-frequency aberrations and the tweeter corrects higher order distortions. In this work, we perform a simulated side-by-side comparison of various control methods for woofer-tweeter adaptive optics systems. Attention is focused on the deep turbulence regime, where the wavefront distortions contain discontinuities. Our simulated wavefronts originate from a cooperative point-like beacon placed at the target plane. The light from the beacon propagates horizontally through multiple kilometers of turbulent atmosphere to the receiving aperture. At the receiver, the wavefronts are interfered with a local reference wave to produce a hologram. Through digital holographic processing, we recover the complex wave field at the receiver, in which the phase contains both branch cuts and branch points. These discontinuities pose a challenging problem for continuous surface mirrors required for high-energy applications. Our study explores the ability of previously published control methods to correct wavefronts with branch points and cuts. Various control methods for woofer-tweeter systems, including zonal and modal methods, are compared using the Strehl ratio and stroke efficiency as performance metrics. The investigation of these control methods will enable future applications to maximize the the stroke of dual deformable mirror adaptive optics systems leading to better energy on target in deep turbulence conditions.

The Shack-Hartmann wavefront sensor has proven to be a valuable detector particularly in the context of turbulence and adaptive optics. In this work we take advantage of its capacity of characterizing orbital-angular-momentum (OAM) states under certain conditions, in the context of a free-space optical communication link. First, we propose a method to compute the locations of the light spots created by the lenslet array that is more robust than the simple centroid formula when atmospheric turbulence is present. Second, we propose a “local OAM” estimation that avoids the computation of a circulation integral in the discrete Shack-Hartmann array. Our proposal does not require prior knowledge of beam diameter or OAM state. We show simulations and laboratory experiments for OAM beams in turbulence conditions at which reliable detection is feasible. We analyze the quality of detection as a function of turbulence strength, Shack-Hartmann resolution and number of acquisitions. These ideas can be applied to coherent coaxial superpositions of two or more OAM states if the light rings are non-overlapping. Using the concept of “optical ferris-wheels” introduced by Franke-Arnold et al. (2007), the detection can be implemented for a limited set of pairs of vortices. We propose a generalization of the recipe for generation of ferris-wheels now for pairs of orthogonal vortices with arbitrary OAM states. The proposal is supported by simulations in turbulence conditions. An extension of our work considers the use of error-correcting codes that take advantage of the large set of available combinations of OAM states.

Laser communications (Lasercomm) for long distance airborne applications offer the potential for secure, high capacity communications outside the traditional radio frequency (RF) spectrum. This paper will present laboratory and field experiments evaluating curvature adaptive optics for Lasercomm terminal architectures to enable long-range (<200 km) and high rate (10’s Gbps) communication links for airborne applications. In particular, the benefits of and requirements to implement higher order adaptive optics correction for airborne systems in addition to tip/tilt correction will be discussed.

A Hartmann Turbulence Sensor (HTS) was used to quantify the atmospheric turbulence along a 1 km near ground-level path. This study examines the effect of removing the average tilt over all subapertures from each subaperture in the data analysis. The HTS captures a laser beam projected along a path of interest with a telescope; a lenslet array in the detector system breaks the beam up into 700 subapertures spread across the telescope pupil, and then forms images of the laser source from each of these subapertures onto a fast camera. Turbulence along the path induces tilts in the laser wavefront which are captured as centroid motion of the many laser spots in the camera image. This motion is used to quantify the turbulence. The raw spot positions contain undesired image motion due to telescope motion and vibration. This motion can be removed from the data by subtracting the average centroid motion of all subapertures from each subaperture. This subtraction changes the data in other ways, and this detail must be included in the analysis. The result can be exactly represented as weighted sum over the differential tilt variances between subapertures pairs. The tilt-removed variance averaged over all the subapertures is shown to be one-half of the average variance over all subaperture pairs. This work also resolves some discrepancies in previous results involving the expected variances of these differential tilts.

Wave Optics Simulations (WOS) are a valuable tool for exploring the effects of atmospheric turbulence on laser beam propagation and imaging. Obtaining accurate results from WOS requires careful selection of simulation parameters. Specifically, the inter-screen spacing, spatial sampling of source and receiver planes, and phase screen sampling are all important parameters. The parameter space for WOS in Kolmogorov turbulence is well characterized and while it is often assumed that similar requirements hold for simulation of non-Kolmogorov atmospheres, we find this is not the case. In this paper we will discuss the practical limits of modeling optical propagation in non-Kolmogorov turbulence using the split-step phase screen method underlying WOS.

In recent years, theoretical studies of optical propagation through turbulence exhibiting statistical anisotropy and a non- Kolmogorov energy spectrum, with a power law unequal to 11/3^rds, have appeared regularly in the literature. In this study, we use split-step propagation wave optics simulations, together with FFT-based subharmonic phase screens to compare long-term beam spreading and scintillation index statistical projections using the Rytov method with theories leveraging coherence length-base perturbation terms. We demonstrate the latter method’s superior accuracy versus simulation for turbulence conditions above the weak fluctuation regime. The necessity of including low spatial frequency subharmonic components, with frequencies below the domain of simulation, to achieve agreement with theory for large magnitudes of the energy spectrum power law is demonstrated. Additionally, a new method of including low frequency components in the phase screens used in simulation with significant computation time improvements relative to the traditional subharmonic method is introduced.

Using numerical simulation, we study the influence of ratio between characteristic scales of a femtosecond mid-IR wave packet on the threshold power of filamentation and light bullets formation under condition of anomalous group velocity dispersion in transparent dielectrics. As the similarity parameter to determine the process of filament formation and light bullet creation was chosen a ratio of the diffraction length to the dispersion length of wave packet. It was found that the threshold power of filamentation, divided by the critical power of stationary self-focusing, does not depend on the wavelength of radiation and parameters of the medium and can be determined by the introduced similarity parameter. It was established that under condition of optimal choice of a parameter (the diffraction length is much smaller than the dispersion length) the threshold power of filamentation. With an increase of the similarity parameter, the threshold power of filamentation and light bullet formation increases. An optimal control of light bullets’ formation can be used at the problems of environmental sensing and transportation of high-density energy in the atmosphere.

The performance of satellite-to-ground downlink optical communications over Gamma-Gamma distributed atmospheric turbulence are discussed for a direct detection differential phase shift keying system with spatial diversity, which combines the beam coherently before demodulation. Bit-error rate (BER) performances for various numbers of apertures are analyzed and compared for different zenith angle. We also consider the effect of the fiber coupling efficiency and loss ratio of beam coupler to the final BER. The results of numerical simulation shows that the advantage increases with the number of aperture. All the numerical results are verified by Monte-Carlo simulations.

With the rapid increase in communication traffic, the capacities of existing multiplexing methods have reached the limits of expandability. Therefore, the mode multiplex communication method using orbital angular momentum (OAM) has recently attracted attention as a new method. The OAM is a part of Laguerre-Gaussian (LG) beam. LG beam which possesses modes determined by the radial order n and the azimuth order m. The OAM is modes when the radial order n is equal to zero. Transmission capacity and spectral efficiency are expected great increase significantly from the combination of existing multiplexing method and mode multiplexing. In the future, a further increase in transmission capacity is expected because devices connected to the Internet are rapidly increasing with the spread of the Internet of Things. Therefore, in order to further increase transmission capacity, it is necessary to expand the radial order n. In this study, we investigate the mode multiplexing communication method using LG mode extending the radial order n. To realize mode multiplexing with increased the amount of multiplexing, technological developments in demultiplexing are particularly significant. In previous studies, mode-demultiplexers have been considered interferometric method and holographic filter. However, these methods have problems such as the complex of optical system and the reduction in diffraction efficiency. Therefore, we design the computer generated hologram that can extract multiple modes with one filter as the mode-demultiplexer. Through the above examination, we aim to realize simplification and high efficiency of the mode-demultiplexer.