Holmium YLF amplifier performance and the prospects for multi-Joule energies using diode-laser pumping

• Published in: IEEE journal of quantum electronics Vol. 29; no. 2; pp. 440 - 451
• Main Author: Storm, M.E.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS IEEE 01.02.1993; Institute of Electrical and Electronics Engineers
• Subjects: 426002 - Engineering- Lasers & Masers- (1990-); ALKALI METAL COMPOUNDS; AMPLIFICATION; COMPARATIVE EVALUATIONS; Diode lasers; DOPED MATERIALS; Doped-insulator lasers and other solid state lasers; ELEMENTS; ENGINEERING; EVALUATION; Exact sciences and technology; FLUORIDES; FLUORINE COMPOUNDS; Fundamental areas of phenomenology (including applications); GAIN; Gain measurement; HALIDES; HALOGEN COMPOUNDS; HOLMIUM; Laser excitation; LASER MATERIALS; Laser modes; Laser theory; LASERS; Lasers And Masers; LITHIUM COMPOUNDS; LITHIUM FLUORIDES; LITHIUM HALIDES; MATERIALS; MATHEMATICAL MODELS; METALS; Optical amplifiers; OPTICAL PUMPING; Optics; Physics; POPULATION INVERSION; Pump lasers; PUMPING; RARE EARTHS; Semiconductor optical amplifiers; SOLID STATE LASERS; Stimulated emission; TRANSITION ELEMENT COMPOUNDS; USES; YTTRIUM COMPOUNDS; YTTRIUM FLUORIDES; Lithium Yttrium Fluorides Mixed; Laser pumping; Holmium; Optical amplifier; Models; Injection laser; Optical amplification; Gain; Semiconductor laser; Solid state laser
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.199299

Laser studies that examined the amplifier characteristics of holmium-doped yttrium lithium fluoride (YLF) at 300 K are discussed. An inversion ratio n/sup 5/I/sub 7//n/sub Ho/ of 0.37 was reached, resulting in a measured small-signal gain coefficient of 0.50 cm/sup -1/. In a flashlamp pumping experiment, an output energy of 240 mJ was achieved for 38.5 mJ of input energy, resulting in a large gain of 6.2. An amplifier model developed for diode laser pumping was adapted to consider this flashlamp-pumped case. The agreement between the theory and the experiment is good. Multipass amplifier calculations using the model suggest that the Ho:Tm:YLF laser crystal can support a 12% electrical to optical efficiency at 300 K, even in the presence of upconversion.< >