This book presents a comprehensive overview of 2 µm fiber laser technology, focusing on rare-earth doped gain systems, pulsed laser generation, nonlinear optical behavior, high-power architectures, and practical applications. It is designed as a technical reference for understanding how mid-infrared fiber lasers are developed, optimized, and applied across scientific, medical, and industrial fields. A central theme of the book is the importance of the 2 µm spectral region. This wavelength range is attractive because it offers eye-safer operation, strong interaction with water and certain gas molecules, compatibility with atmospheric sensing, and potential for nonlinear frequency conversion into longer mid-infrared wavelengths. These properties make 2 µm fiber lasers useful for spectroscopy, sensing, surgery, materials processing, and emerging photonic technologies. The book gives significant attention to rare-earth doped fiber laser systems, especially those based on thulium, holmium, and thulium-holmium co-doped fibers. Another major focus is pulse generation at 2 µm, particularly through Q-switching and mode-locking.

Dr. Kok-Sing Lim received his Ph.D. in physics from the University of Malaya. Currently, he is Associate Professor at Photonics Research Centre, University of Malaya. His research interests include fiber Bragg grating (FBG), optical measurement and instrumentation and fiber lasers.

Bilal Nizamani is a Senior Lecturer at the Photonics Research Centre, Universiti Malaya. He received his PhD in Photonics from Universiti Malaya in 2021. His research interests include high-power fiber lasers, Q-switched and ultrafast mode-locked lasers, fluoride fibers, saturable absorbers, rare-earth-doped fibers, optical sensors, and photonic communications and optical systems.

Mohammad Faizal Ismail is a Research Officer at the Photonics Research Centre, Universiti Malaya. He holds a PhD in Photonic Technology and degrees in engineering from Universiti Malaya. His research contributions span fiber lasers, fiber Bragg grating sensors, nonlinear photonics, photodetectors, optical communications, and photonics-based sensing technologies and applications.

Muhamad Zharif Samion is a Research Officer at the Photonics Research Centre, Universiti Malaya. He holds a PhD in Photonics Engineering and a Bachelor of Electrical Engineering. His research encompasses ultrafast and high-power fiber lasers, 2 µm laser systems, fiber-optic sensing, nonlinear photonics, and advanced photonic technologies and applications.

Muhammad Khairol Annuar Zaini is a Research Officer at the Photonics Research Centre, Universiti Malaya. He received his PhD in Photonics Engineering in 2021. His expertise includes spatial-mode excitation, space-division multiplexing, fiber Bragg grating sensors, high-power fiber-laser system design, nonlinear photonics, and laser packaging for medical and industrial systems.