Since the first report in 1964, laser damage (LD) of optical materials continues to limit the output energy and power of pulsed and continuous-wave laser systems. In spite of some 50 years of research efforts in this area, interest of the international laser community to laser damage issues remains at a very high level and even increases with the development of novel laser systems. The interest is evident from the high level of attendance and presentations at the annual SPIE Laser Damage Symposium (aka, Boulder Damage Symposium) that has been held in Boulder, Colorado, since 1969. Intensive developments of high-power lasers and applications in Southeast Asia have motivated establishing a partner Pacific Rim Laser Damage conference, first held in 2009 by Shanghai Institute of Optics and Mechanics (China) in cooperation with SPIE. Since the first special section of Optical Engineering on laser damage (December 2012), many significant results have been presented at those two meetings. This special section of Optical Engineering is the second one prepared in response to continuously growing interest from the international laser-damage community. Also, it has been motivated by multiple requests from researchers of that community and by the pivotal success of the first special section on laser damage. Some papers from this special section were presented at the Laser Damage Symposium and Pacific Rim Laser Damage conference; others were submitted in response to the general call for papers for this special section.

The 16 papers selected out of 21 submissions and compiled into this special section represent the entire broad area of laser-damage research. The fundamental mechanisms of LD are considered by Mitchell et al. (particle-in-cell simulations of surface damage), and Gruzdev (laser-induced ionization of solids). Various aspects of multilayer coating and thin-film characterization are considered in papers by Papernov et al. (near-UV absorption annealing of ${\mathrm{HfO}}_2$ films), Douti et al. (LD of thin films with multiple subpicosecond pulses), and Field et al. (effect of cleaning methods on LD of antireflection coatings). Material characterization is represented by the papers devoted to laser calorimetric measurements of low absorption (Balasa et al.), and accelerated lifetime testing of fused silica (Mühlig and Bublitz). Laser-metal interaction is covered by the papers of Rubenchik et al. (temperature-dependent absorption), and Baumann et al. (laser-induced heating and penetration in share flow). Measurements related to LD are considered in papers by Hildenbrand et al. (LD measurements in nonlinear crystals ${\mathrm{CdSiP}}_2$ and Zn ${\mathrm{GeP}}_2$), Stratan (effective laser spot measurements), and Arenberg and Thomas (statistical treatment of measurements of the LD threshold). Papers of Lu et al. (effect of etching on LD properties of artificial defects) and Ding et al. (ultrasonic cleaning for optical substrates with artificial defects) are from the extended field of surface characterization and LD. Another paper is devoted to single-mode fiber degradation by 405-nm CW laser (Gonschior). Finally, characterization of peening-induced effects by thermoelectric methods is considered by Carreon et al.

The emerging research developments in the field of laser damage and optical materials for high-power lasers represented by these papers will be very beneficial for readers of Optical Engineering and researchers from multiple related areas.