1. GOOGL
ND YAG LASER
Nd:YAG (neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12) is a crystal that is used
as a lasing medium for solid-state lasers. The dopant, triply ionized neodymium, Nd(III),
typically replaces a small fraction of the yttrium ions in the host crystal structure of the
yttrium aluminium garnet (YAG), since the two ions are of similar size. It is the neodymium
ion which provides the lasing activity in the crystal, in the same fashion as red chromium ion
in ruby lasers. Generally the crystalline YAG host is doped with around 1% neodymium by
atomic percent.[1
Laser operation of Nd:YAG was first demonstrated by J. E. Geusic et al. at Bell Laboratories in
1964.[2
Contents [hide
Technology
Applications
Medicine
Manufacturing
Fluid dynamics
Dentistry
Military and defense
Cavity ring-down spectroscopy (CRDS
Laser-induced breakdown spectroscopy (LIBS
Laser pumping
Automotive
Additional frequencies
Physical and chemical properties of Nd:YAG
Properties of YAG crystal
Refractive index of Nd:YAG
Properties of Nd:YAG @ 25 °C (with 1% Nd doping
References and notes
Technology[edit

2. Neodymium ions in various types of ionic crystals, and also in glasses, act as a laser gain
medium, typically emitting 1064 nm light from a particular atomic transition in the
neodymium ion, after being "pumped" into excitation from an external source
Nd:YAG lasers are optically pumped using a flashtube or laser diodes. These are one of the
most common types of laser, and are used for many different applications. Nd:YAG lasers
typically emit light with a wavelength of 1064 nm, in the infrared.[3] However, there are also
transitions near 940, 1120, 1320, and 1440 nm. Nd:YAG lasers operate in both pulsed and
continuous mode. Pulsed Nd:YAG lasers are typically operated in the so-called Q-switching
mode: An optical switch is inserted in the laser cavity waiting for a maximum population
inversion in the neodymium ions before it opens. Then the light wave can run through the
cavity, depopulating the excited laser medium at maximum population inversion. In this Qswitched mode, output powers of 250 megawatts and pulse durations of 10 to 25
nanoseconds have been achieved.[4] The high-intensity pulses may be efficiently frequency
doubled to generate laser light at 532 nm, or higher harmonics at 355 and 266 nm
Nd:YAG absorbs mostly in the bands between 730–760 nm and 790–820 nm.[3] At low
current densities krypton flashlamps have higher output in those bands than do the more
common xenon lamps, which produce more light at around 900 nm. The former are
therefore more efficient for pumping Nd:YAG lasers.[5
The amount of the neodymium dopant in the material varies according to its use. For
continuous wave output, the doping is significantly lower than for pulsed lasers. The lightly
doped CW rods can be optically distinguished by being less colored, almost white, while
higher-doped rods are pink-purplish
Other common host materials for neodymium are: YLF (yttrium lithium fluoride, 1047 and
1053 nm), YVO4 (yttrium orthovanadate, 1064 nm), and glass. A particular host material is
chosen in order to obtain a desired combination of optical, mechanical, and thermal
properties. Nd:YAG lasers and variants are pumped either by flashtubes, continuous gas
discharge lamps, or near-infrared laser diodes (DPSS lasers). Prestabilized laser (PSL) types of
Nd:YAG lasers have proved to be particularly useful in providing the main beams for
gravitational wave interferometers such as LIGO, VIRGO, GEO600 and TAMA
Applications[edit
Medicine[edit

3. Slit lamp photo of posterior capsular opacification visible a few months after implantation of
intraocular lens in eye, seen on retroillumination
Nd:YAG lasers are used in ophthalmology to correct posterior capsular opacification, a
condition that may occur after cataract surgery, and for peripheral iridotomy in patients
with acute angle-closure glaucoma, where it has superseded surgical iridectomy. Frequencydoubled Nd:YAG lasers (wavelength 532 nm) are used for pan-retinal photocoagulation in
patients with diabetic retinopathy
Nd:YAG lasers emitting light at 1064 nm have been the most widely used laser for laserinduced thermotherapy, in which benign or malignant lesions in various organs are ablated
by the beam
In oncology, Nd:YAG lasers can be used to remove skin cancers.[6] They are also used to
reduce benign thyroid nodules,[7] and to destroy primary and secondary malignant liver
lesions.[8][9
To treat benign prostatic hyperplasia (BPH), Nd:YAG lasers can be used for laser prostate
surgery—a form of transurethral resection of the prostate
These lasers are also used extensively in the field of cosmetic medicine for laser hair removal
and the treatment of minor vascular defects such as spider veins on the face and legs.
Recently used for dissecting cellulitis, a rare skin disease usually occurring on the scalp
Using hysteroscopy the Nd:YAG laser has been used for removal of uterine septa within the
inside of the uterus.[10
In podiatry, the Nd:YAG laser is being used to treat onychomycosis, which is fungus infection
of the toenail.[11] The merits of laser treatment of these infections are not yet clear, and
research is being done to establish effectiveness.[12][13
Manufacturing[edit
Nd:YAG lasers are used in manufacturing for engraving, etching, or marking a variety of
metals and plastics. They are extensively used in manufacturing for cutting and welding
steel, semiconductors and various alloys. For automotive applications (cutting and welding
steel) the power levels are typically 1–5 kW. Super alloy drilling (for gas turbine parts)
typically uses pulsed Nd:YAG lasers (millisecond pulses, not Q-switched). Nd:YAG lasers are
also employed to make subsurface markings in transparent materials such as glass or acrylic
glass. Lasers of up to 400 W are used for selective laser melting of metals in additive layered
manufacturing. In aerospace applications, they can be used to drill cooling holes for
enhanced air flow/heat exhaust efficiency.[citation needed
Nd:YAG lasers are also used in the non-conventional rapid prototyping process light
engineered net shaping (LENS
Fluid dynamics[edit

4. Nd:YAG lasers can also be used for flow visualization techniques in fluid dynamics (for
example particle image velocimetry or laser induced fluorescence).[14
Dentistry[edit
Nd:YAG lasers are used for soft tissue surgeries in the oral cavity, such as gingivectomy,
periodontal sulcular debridement, LANAP, frenectomy, biopsy, and coagulation of graft
donor sites
Military and defense[edit
Military surplus Nd:YAG laser rangefinder firing. The laser fires through a collimator, focusing
the beam, which blasts a hole through a rubber block, releasing a burst of plasma
The Nd:YAG laser is the most common laser used in laser designators and laser rangefinders
Cavity ring-down spectroscopy (CRDS)[edit
The Nd:YAG may be used in the application of cavity ring-down spectroscopy, which is used
to measure the concentration of some light-absorbing substance
Laser-induced breakdown spectroscopy (LIBS)[edit
Main article: Laser-induced breakdown spectroscopy
A range of Nd:YAG lasers are used in analysis of elements in the periodic table. Though the
application by itself is fairly new with respect to conventional methods such as XRF or ICP, it
has proven to be less time consuming and a cheaper option to test element concentrations.
A high-power Nd:YAG laser is focused onto the sample surface to produce plasma. Light
from the plasma is captured by spectrometers and the characteristic spectra of each
element can be identified, allowing concentrations of elements in the sample to be
measured
Laser pumping[edit
Nd:YAG lasers, mainly via their second and third harmonics, are widely used to excite dye
lasers either in the liquid[15] or solid state.[16] They are also used as pump sources for
vibronically broadened solid-state lasers such as Cr4+:YAG or via the second harmonic for
pumping Ti:sapphire lasers
Automotive[edit
Researchers from Japan's National Institutes of Natural Sciences are developing laser igniters
that use YAG chips to ignite fuel in an engine, in place of a spark plug.[17][18] The lasers use
several 800 picosecond long pulses to ignite the fuel, producing faster and more uniform
ignition. The researchers say that such igniters could yield better performance and fuel
economy, with fewer harmful emissions

5. Additional frequencies[edit
For many applications, the infrared light is frequency-doubled or -tripled using nonlinear
optical materials such as lithium triborate to obtain visible (532 nm, green) or ultraviolet
light. Cesium lithium borate generates the 4th and 5th harmonics of the Nd:YAG 1064 nm
fundamental wavelength. A green laser pointer is a frequency doubled Nd:YVO4 DPSS laser.
Nd:YAG can be also made to lase at its non-principal wavelength. The line at 946 nm is
typically employed in "blue laser pointer" DPSS lasers, where it is doubled to 473 nm
Physical and chemical properties of Nd:YAG[edit
Properties of YAG crystal[edit
Formula: Y3Al5O12
Molecular weight: 596.7
Crystal structure: Cubic
Hardness: 8–8.5 (Moh
Melting point: 1950 °C (3540 °F
Density: 4.55 g/cm3
Refractive index of Nd:YAG[edit
Index n (25 °C
Wavelength (μm)
citation needed
Properties of Nd:YAG @ 25 °C (with 1% Nd doping)[edit
Formula: Y2.97Nd0.03Al5O12
Weight of Nd: 0.725%

6. Atoms of Nd per unit volume: 1.38×1020 /cm3
Charge state of Nd: 3
Emission wavelength: 1064 nm
Transition: 4F3/2 → 4I11/2
Duration of fluorescence: 230 μs
Thermal conductivity: 0.14 W·cm−1·K−1
Specific heat capacity: 0.59 J·g−1·K−1
Thermal expansion: 6.9×10−6 K−1
dn/dT: 7.3×10−6 K−1
Young's modulus: 3.17×104 K·g/mm−2
Poisson's ratio: 0.25
Resistance to thermal shock: 790 W·m−1
References and notes[edit
Jump up ^ Koechner §2.3, pp. 48–53
Jump up ^ Geusic, J. E.; Marcos, H. M.; Van Uitert, L. G. (1964). "Laser oscillations in nddoped yttrium aluminum, yttrium gallium and gadolinium garnets". Applied Physics Letters 4
(10): 182. Bibcode:1964ApPhL...4..182G. doi:10.1063/1.1753928
Jump up to: a b Yariv, Amnon (1989). Quantum Electronics (3rd ed.). Wiley. pp. 208–211.
ISBN 0-471-60997-8
Jump up ^ Walter Koechner (1965) Solid-state laser engineering, Springer-Verlag, p. 507
Jump up ^ Koechner §6.1.1, pp. 251–264
Jump up ^ Moskalik, K; A Kozlov, E Demin, and E Boiko (2009). "The Efficacy of Facial Skin
Cancer Treatment with High-Energy Pulsed Neodymium and Nd:YAG Lasers". Photomedical
Laser Surgery 27 (2): 345–9. doi:10.1089/pho.2008.2327. PMID 19382838
Jump up ^ Valcavi R, Riganti F, Bertani A, Formisano D, Pacella CM. (November 2010).
"Percutaneous Laser Ablation of Cold Benign Thyroid Nodules: A 3-Year Follow-Up Study in
122 Patients". Thyroid 20 (11): 1253–61. doi:10.1089/thy.2010.0189. PMID 20929405
Jump up ^ Pacella CM , Francica G , Di Lascio FM , Arienti V , Antico E , Caspani B , Magnolfi F
, Megna AS , Pretolani S , Regine R , Sponza M , Stasi R . (June 2009). "Long-term outcome of
cirrhotic patients with early hepatocellular carcinoma treated with ultrasound-guided

7. percutaneous laser ablation: a retrospective analysis". Journal of Clinical Oncology 27 (16):
2615–21. doi:10.1200/JCO.2008.19.0082. PMID 19332729
Jump up ^ Pompili M , Pacella CM , Francica G , Angelico M , Tisone G , Craboledda P ,
Nicolardi E , Rapaccini GL , Gasbarrini G . (June 2010). "Percutaneous laser ablation of
hepatocellular carcinoma in patients with liver cirrhosis awaiting liver transplantation".
European Journal of Radiology 74 (3): e6–e11. doi:10.1016/j.ejrad.2009.03.012. PMID
19345541
Jump up ^ Yang J, Yin TL, Xu WM, Xia LB, Li AB, Hu J. (2006). "Reproductive outcome of
septate uterus after hysteroscopic treatment with neodymium:YAG laser". Photomed Laser
Surg. 24 (5): 625. doi:10.1089/pho.2006.24.625. PMID 17069494
Jump up ^ Ledon, Jennifer A.; Savas, Jessica; Franca, Katlein; Chacon, Anna; Nouri, Keyvan
(2012). "Laser and light therapy for onychomycosis: a systematic review". Lasers in Medical
Science.doi:10.1007/s10103-012-1232-y. ISSN 0268-8921
Jump up ^ Mozena, John; Haverstock, Brent (May 2010). "Laser care for onychomycosis: can
it be effective?". Podiatry Today 23 (5): 54–59
Jump up ^ Mozena, John D.; Mitnick, Joshua P. (October 2009). "Emerging concepts in
treating onychomycosis". Podiatry Today 22 (10): 46–51
Jump up ^ Palafox, Gilbert N.; Wicker, Ryan B.; and Elkins, Christopher J. (2003). "Rapid invitro physiologic flow experimentation using rapid prototyping and particle image
velocimetry" (pdf). 2003 Summer Bioengineering Conference: 419. Retrieved 2007-10-10
Jump up ^ F. P. Schäfer (Ed.), Dye Lasers (Springer-Verlag, Berlin, 1990
Jump up ^ F. J. Duarte, Tunable Laser Optics (Elsevier-Academic, New York, 2003
Jump up ^ Coxworth, Ben (April 21, 2011). "Laser igniters could spell the end for the humble
spark plug". Gizmag.Retrieved March 30, 2012
Jump up ^ Pavel, Nicolaie; et al. (2011). "Composite, all-ceramics, high-peak power
Nd:YAG/Cr4+:YAG monolithic micro-laser with multiple-beam output for engine ignition".
Optics Express 19 (10): 9378–9384. Bibcode:2011OExpr..19.9378P. doi:10.1364/
/OE.19.009378. PMID 21643194.O