2169-3536 (c) 2017 IEEE. Translations and content mining are permitted for academic research only. Personal use is also permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/ACCESS.2017.2755678, IEEE Access Applications of Lasers for Tactical Military Operations Hemani Kaushal, Member IEEE and Georges Kaddoum, Member IEEE Abstract— Laser technology has observed a great advancement over the last few decades. This technology is used for a wide range of applications including medical sciences, military, industrial manufacturing, electronics, holography, spectroscopy, astronomy and much more. Military operations often demand a secure and timely transmission of a massive amount of information from one place to another. Until now, the military has relied on the radio spectrum for effective communication, which is vulnerable to security threats and susceptible to electromagnetic interference (EMI). Also, this spectrum is hard-pressed to meet the current bandwidth requirement for high-resolution images, on-air video conferencing and real-time data transfer. Therefore, the focus has shifted to visible and infrared (IR) spectrum using laser technology which is capable of providing secure data transfer because of its immunity to EMI. The probability of intercepting a laser signal is very low due to its narrow beam divergence and coherent optical beam, making the laser a suitable candidate for secure military tactical operations. Besides the communication aspect, the highly directive nature of a laser beam is also used as a directed energy laser weapon. These highly powerful and light weighted directed energy laser weapons are very cost-effective countermeasures for airborne threats. Furthermore, laser sensors are deployed in the battlefield or in space for tracking the path of a wide range of military vehicles like missiles, unmanned aerial vehicles (UAVs), fighter aircraft, warships, submarines, etc. Advancements in space operations and laser technology have offered synergistic possibilities of using lasers from space-based platforms during military operations. In this paper, we are providing our readers with a comprehensive study of laser applications, used by the military, to carry out tactical operations on the ground or space-based platforms. Also, an intensive investigation on the development of laser technology for sensors, range-finders and target designators that are used for intelligence, surveillance and reconnaissance (ISR) is presented in the paper. The advancement of laser communication for military purposes and its current state of the art is reviewed as well as some recent scientific developments in the area of high-energy directed laser weapons are discussed, which have revolutionized military battlefields. Therefore, this manuscript highlights recent trends and engineering breakthroughs for the use of lasers in tactical operations. Index Terms—Laser communication, laser range finders, laser sensors, laser weapons, jamming, data relay, ultraviolet commu- nications, hybrid optical/radio-frequency link, weather modifica- tion, holographic projection. H. Kaushal is with Department of Electrical, Electronics and Communica- tion Engineering, The NorthCap University, Gurgaon, India. (email: himaniz@yahoo.com) G. Kaddoum is with Département de génie électrique, University of Québec, École de technologie supérieure, Montréal (QC), Canada. (email: georges.kaddoum@etsmlt.ca) I. I NTRODUCTION Laser technology has observed great scientific developments and engineering improvements that make it usable for various commercial, industrial, medical and scientific applications. The lasers have already brought great benefits in photography, spectroscopy, holography, data storage, surgery and much more. It uses the phenomenon of stimulated emission to generate a coherent optical beam that offers a wide variety of functionalities for various applications. There are variety of lasers available in the market today with different wavelengths, spectral bandwidth, power levels, operating efficiencies and temporal characteristics. This increasing maturity of lasers and compact optical systems have enhanced their capabilities for military operations. Military officials have indubitably always been interested in laser technology, even before the first laser was invented. Especially, since these devices can bring technological revolution in warfare, when used as range- finders, target designation, sensors, active illumination, data relay devices, directed energy weapons, weather modifier and much more. Ever since the first demonstration of laser by flashing light through a ruby crystal in California’s Hughes Research Laboratory in 1960, it took almost 50 years to bring them for practical use in the battlefield [1]. From the 1970s to mid-1990s, the use of radio frequency (RF) along with digital signal processing techniques has shown dominance in military warfare. However, RF is not capable of handling the ever-increasing demand of information in military operations that uses electronic warfare systems, spread- spectrum communications, wide bandwidth radar systems, etc. For all these military applications that require huge capacity and real time processing over wide dynamic ranges, lasers are considered a good choice over RF signals. Over the years, laser technology has sufficiently matured to provide cost-effective, energy efficient, high-speed and wavelength-flexible systems that can be used for a variety of military operations such as commutation, remote sensors, directed energy weapons, etc. The laser technology offers several benefits over con- ventional RF or microwave systems for tactical operations. Although traditional RF and microwave frequencies are excelling on many fronts, they become vulnerable or non- effective under certain scenarios such as real-time threats, tapping, jamming, low bit rate, high latency, large size, weight and power (SWaP). Since the bandwidth provided by the optical system (due to high carrier frequency) is much higher than the radio or microwave systems’, lasers are capable of disseminating large volumes of data or video information in the battlefield, often in real time. Successfully demonstrating