Disk laser technology: Solid state lasers for industrial micro material processing and medical treatments. light waves from laser contain only one wavelength or color The use of an external resonant cavity allows enhancement of the optical field at the position of the doubling crystal, leading to efficient doubling. It probably will be challenged for use in some applications by the development of new solid state laser materials. The most important features which make the thin disk laser distinguishable between solid state lasers are power scalability, good beam quality and minimal thermal lensing [47,48]. The pump power does not affect the pulse energy. Another crucial advantage will be that laser diodes will be able to fire up to ten billion times without being replaced, whereas the large flashlamps used in present-day ICF lasers have to be replaced after about 100,000 shots—and in an application like LIFE, this would be less than a single day’s operation. Neon (Ne) lasers, argon ion lasers, carbon dioxide lasers a glass or crystalline. Figure 6-2. Tunable solid state lasers are replacing dye lasers for some spectroscopic applications. The expression ‘gas or solid-state laser’ has to do exactly with these material options and the resulting specifications of the laser. A dye laser is an example of the liquid laser. Because the efficiency of frequency doubling increases with the optical power, doubling is usually performed with the doubling crystal in a resonant optical cavity to increase the power level. A diode-pumped solid-state laser (DPSSL) is a solid-state laser made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal, with a laser diode. In these lasers, glass or crystalline materials are Copyright © 2021 Elsevier B.V. or its licensors or contributors. Formally, the class of solid-state lasers includes also fiber laser, as the active medium (fiber) is in the In this case, the laser intensity strongly bleaches the saturable absorber and reduces the cavity loss such that the intensity inside the laser grows too fast for the gain saturation to follow (Fig. In the microchip laser the mirrors of the oscillator are directly deposited on the parallel polished faces of a thin (several hundred micrometers up to a few millimeters) wafer of a laser material such as neodymium-doped YAG Mermilliod et al. ways: coherence, directionality, monochromacity, and high A diode-pumped solid-state laser (DPSSL) is a solid-state laser made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal, with a laser diode. 10. The overall efficiency of a diode-pumped solid-state laser can be as high as 10–20%, due to the high efficiency of the diodes in converting electrical energy into light and also due to the efficiency with which the light can be coupled into the neodymium atoms. lasers, light energy is used as pumping source. These phenomena are less often encountered now with commercial solid state lasers, for which the manufacturers now ensure that components are not exposed to laser irradiance above the damage threshold. Diode-pumped solid-state lasers are replacing flashlamp-pumped lasers in many scientific and industrial applications. Semiconductor Figure 4-1. The damage threshold for a given laser material shows a great deal of scatter because of variation among individual specimens. Potential applications for these devices include laser radar, micromachining, and environmental monitoring. One common type of optically pumped lasers is the diode pumped solid-state laser (DPSSL), which in this specification will serve as the illustrative, non-limiting example. is concentrated on a narrow region.Therefore, laser In gas lasers, the laser medium is in the The workhorse by far is still Nd:YAG with Nd:YVO 4 becoming increasingly important for low to medium power (up to a few watts) 1,064 nm and frequency doubled 532 nm (green) diode pumped solid state lasers. Gas lasers are of different types: they are, Helium (He) – Typically optical pumping is less efficient than electrical excitation. rare-earth elements other than neodymium (holmium, erbium, thulium) lasers, such as Ho:YAG, Er:glass, Er:YAG, Tm:YAG, emitting at about 2 μm depending on the matrix and doped material used. Thus, advances in the development of stable high-power continuous green solid state lasers are likely to be slow. Rare earth elements such as medium used: A Since the success in generating continuous-wave (c.w.) Models of stable green Nd:YAG lasers have been developed using both intracavity doubling and external cavity doubling. Solid state lasing media are typically optically pumped, using either a flashlamp or arc lamp, or by laser diodes. optical gain is produced within the semiconductor material. Lasers gaseous state. The design shown in the figure could be considered typical, but there have been many variations, including frequency-doubled devices operating in the green. They should continue to develop. Instead of CO2 gas, the gain medium is a solid material (hence the term solid state), usually a crystal of yttrium aluminum garnet (YAG) doped, or coated, with an active material, most often the elements neodymium (Nd:YAG) or ytterbium (Yb:YAG). Diode-pumped microchip lasers are very small, efficient, and easy to fabricate. 1.15, Gas lasers are of different types: they are, Helium (He) – The lithium tantalate Q-switch is also in the form of a small chip, located in close proximity to the Nd:YAG. processes. Operation in a single axial mode has permitted the study of injection locking as a means of increasing the power of the laser source while preserving the narrow linewidth. In addition, diode-pumped solid state lasers are moving into the ultraviolet. with very high beam quality and long coherence lengths. stimulated emission of radiation which increases the Garry McCracken, Peter Stott, in Fusion (Second Edition), 2013. Stephen A. Payne, Georg F. Albrecht, in Encyclopedia of Physical Science and Technology (Third Edition), 2003. Rather than being a disadvantage, this broad bandwidth enables the design of tunable and ultrafast (femtosecond and picosecond pulse width) lasers. Solid state lasers are replacing dye, ion and HeNe type lasers in certain markets. Because that is what works - chemical pumping could not be used on solid state because they are solid - chemicals can't get in. thermal effects: profile refractive index profile Another important area involves advances in solid state laser technology at shorter wavelengths, especially in the green portion of the spectrum. The laser diode peak power is limited; output pulses produce only a small increase in peak power. Lasers are classified based on their potential for causing injury — especially eye damage, since the eye is most susceptible to excess laser light. The mirrors are made of a stack of SiO2 and TiO2 films (20–40 layers) with a total thickness of 1–2 μm. Ruby laser is the first successful laser developed by Maiman in 1960. a laser light beam in the infrared region of the spectrum at For short Q-switched pulses, we need a short cavity length, which also lowers the threshold for Q-switching (see Eq. do not belong to this category because these lasers are cerium (Ce), erbium (Eu), terbium (Tb) etc are most commonly The data presented in Figure 6-2 indicate that if a given laser fluence is required, one should operate at relatively low values of peak power and make the pulse duration as long as possible. a laser light beam in the infrared region of the spectrum at It (CO, Copyright Solid state lasers date back to the 1960s with the first laser ever invented being of the laser variety. Many favorable characteristics such as Although the ruby laser is operated mainly in the pulsed regime, typically delivering a few joules of energy per pulse, the other two media are very versatile and are well suited to both pulsed and CW operation (Walling and Peterson, 1980; Walling et al., 1980a; Moulton, 1986). 2). But if a high value of irradiance is needed, the pulse duration should be shortened in order to reduce the total fluence. Diode laser pumped solid state lasers, frequency extended by nonlinear techniques, are compact highly coherent sources of optical radiation that are useful for spectroscopic applications. By continuing you agree to the use of cookies. converting electrical energy into light energy. The We may expect to see diode-pumped frequency-doubled Nd:YAG lasers replacing argon lasers in areas where electrical power, size, and cooling are important issues. © 2013-2015, Physics and Radio-Electronics, All rights reserved, SAT Ursula Keller, in Semiconductors and Semimetals, 1998. Other Examples of Home-Built PSS Lasers Mini YAG Laser using SSY1 Optics and SG-SP1 I (Sam) was given a cute little YAG cavity including a 50 mm long 3 mm diameter Nd:YAG rod with AR coated ends and a flashlamp similar to that used in SSY1. However, the intensity is now so high that the gain saturation continues during the pulse decay time. Solid-state laser. Damage may occur both internally within the rod and at the ends of the rod. Although still far more expensive than flash lamp pumping, it is the method of choice where efficiency is a premium, as is the case for most military applications. (27) and (28) suggest that for optimized pulse duration and pulse energy a large ΔR is desirable. Our disk lasers are fitted with thin disk like Nd:YVO4 or Yb:KYW that function as the laser medium. Strongly focused wavefront for a 3-mm-diameter Nd:YALO rod was reconstructed using 4th-order Zernike polynomials, with all polynomial terms retained (top) and with the tilt and focus-shift terms removed (bottom). These lasers are very cheap, compact size and consume * Submit Cancel Browse Applications Browse Lab/OEM Lasers Browse Products Find Lasers by Specification Find Lasers by Specification . The lamp was similar to what is used for indoor and high speed A solid-state laser uses ore such as yttrium, aluminum, and garnet or yttrium vanadate crystal (YVO 4) as the laser medium. Using CVL pumping, narrow-linewidth emission has been demonstrated at average powers of 5 W at 6.2 kHz, at a conversion efficiency of ∼26% (Coutts et al., 1998). lensing in a solid-state laser rod. Here it is described how the generation of coherent radiation occurs, why a pulsed device is more powerful, for which engraving is needed. the substance is called doping. The growth rate between the pulse, is then given by gf0/rL, as long as we can neglect spontaneous emission. These levels then decay to the upper laser level, which acts much like a temporary storage reservoir, collecting enough population to make a large inversion with respect to lower lying levels that have a rapid decay to the ground state. Thus, the intensity continues to increase until finally the gain is saturated to the cavity loss level. In this laser the lasing is a result of atomic transitions of an impurity atom in a crystalline host. the, Semiconductor Ruby laser is one of the few solid-state lasers that produce visible light. It is a gas laser built by Ali Javan at MIT, with a wavelength of 632.8 nm and a linewidth of only 10kHz. intensity. Back to Solid State Lasers Sub-Table of Contents. The damage is viewed by scattering of He–Ne laser light traversing the rod axis. discharged through a gas inside the laser medium to produce The result is that there are basically few uninverted ions left in the active medium. Numerical simulations of the Q-switching dynamics show that we obtain the largest extracted pulse energy under given pumping conditions if the modulation depth of the absorber is as large as the output coupling and the absorber is fully bleached by the pulse energy (Spühler et al., 1998). Maser, device that produces and amplifies electromagnetic radiation mainly in the microwave region of the spectrum.The maser operates according to the same basic principle as the laser (the name of which is formed from the acronym for “light amplification by stimulated emission of radiation”) and shares many of its characteristics. Lamp-pumped solid state lasers were developed early in the history of lasers and after some time reached a level of maturity. Studybay uses cookies to ensure that we give you the best experience on our website. laser beam is very narrow and can be concentrated on a very All-solid-state lasers typically have specific advantages over gas lasers, for example in terms of compactness and lifetime. Therefore this laser is a natural transmitter of digital data. In other words, unlike a flash lamp, the diode pump array only emits light at a wavelength that is actually used by the active ion to build up inversion. The original laser invented in 1960 was a solid state laser. Zinc / cadmium chalcogenide lasers doped with transition metals (chromium, iron) (TM 2+:A II B VI, … The The mirrors are denoted M. The source of voltage for the Q-switch is denoted V. Because the laser cavity is very short, there will be only one longitudinal mode within the gain curve of the material. of phase. The most common example is the Ti:sapphire laser. solid-state small area. The long carrier lifetime has the additional advantage that the semiconductor absorber has fewer defects, resulting in minimal nonsaturable loss. which types of lasers are used in laser beam machining? as the pump source. At an irradiance around 3 × 109 W/cm2, damage is produced within a single pulse. Table 6-1. The data represent the number of pulses that could be extracted from a ruby laser under constant excitation conditions before the output was reduced by 30 percent. This represents a glass with relatively high damage threshold. This page also describes noble gas flash lamps and flash lamps used for lamp excitation. The first 4-level solid-state laser, the second operating type of laser (after the Mayman ruby laser), cooled with liquid helium, is not used anywhere today. states of organic dyes dissolved in liquid solvents. as a laser medium. As long as the pulse repetition rate frep is much greater than the inverse of the upper state lifetime τL of the laser (i.e., frep ≥ 2/τl), it can be shown that. Such devices could have applications in microelectronic fabrication, optical disks, and medicine. usually electrically pumped and involve different physical diodes. 56 kW of electric current is used by a CO2 laser to generate a laser capacity of 4 kW, while a solid-state laser requires just 17 kW, an energy savings of 70 percent. As the circulating pulse becomes shorter, the pulse shortening action of the modulator is reduced, while pulse broadening effects become stronger. Q-switched frequency-quadrupled Nd:YAG lasers operating at 266 nm are available with average power near 1 W. Another research trend involves the development of microchip laser devices. This means that the microchip lasers are stable, single-mode devices. Ion-doped solid-state lasers (also sometimes called doped insulator lasers) can be made in the form of bulk lasers, fiber lasers, or other types of waveguide lasers. laser is different from conventional light sources in four A dye laser is 93(2-3), 269–316 (2008). The original solid state laser was a ruby laser that generated an intense flash of blue-white light. Q-switched green solid state diode-pumped lasers are available with average power outputs at the multiwatt level. Output power is also not very high as in CO2 lasers. This configuration uses flat mirrors and is very simple to fabricate. Hence, all the photons emitted by laser light It is also likely that green diode-pumped solid state lasers will replace argon lasers for pumping Ti:sapphire lasers and will replace lamp-pumped Nd:YAG lasers for some micromachining applications. In one example of this laser, ytterbium-doped optical fibre is end-pumped with a diode laser, however, several different designs and fibre cladding technologies exist and compete in the market for materials processing. The irradiance that can be tolerated without damage decreases as the pulse duration becomes longer. Nd:YAG has been the dominant solid state laser material for many years. The first laser ever made, the ruby laser, was a solid-state laser. Ions Damage in a ⅝-in.-diameter ruby rod occurring after 20 shots at 200 MW power. such The An example involves the program on laser-assisted thermonuclear fusion, in which extensive efforts to reduce damaging effects have been employed. Diode-pumped solid-state lasers tend to be much more efficient and have become much more common as the cost of high-power semiconductor lasers has decreased. laser, Materials In liquid lasers, light supplies energy to the laser These materials are pumped optically using a shorter wavelength than the lasing wavelength, often from a flashtube or from another laser. the near infrared (IR) region of the spectrum. Smaller size and appearance make them good choice for many applications. Sam's laser faq solid state lasers. a laser that uses an organic dye (liquid solution) as the It emits light through a process called Single frequency operation has also allowed resonant enhanced harmonic generation for efficient doubling of low power cw laser sources[4] and recently has led to cw operation of a lithium niobate optical parametric oscillator[5]. A new, scalable concept for diode-pumped high-power solid-state lasers is presented. Extremely precise thermal control is required to stabilize such lasers. Figure 7.1: Theodore Maiman with the first Ruby Laser in 1960 and a cross sectional view of the first device [4]. The data shown in Figure 6-2 represent damage produced within a single laser pulse. The process of adding impurities to the substance is called doping. The external optical pump source is a diode laser that excites the active ions of the laser material. This method has remained a laboratory specialty that has never matured outside the scientific marketplace due to the very small overall efficiency and system complexity it entails. But argon lasers are inefficient, large, and expensive. Home; Contact The fabrication of microchip lasers is very simple, and well suited to mass production. (1991). are introduced as impurities into host material which can be Laboratory demonstrations have yielded more than 1 W of continuous output from a frequency-quadrupled Nd:YAG laser at 266 nm. Radiation. This is a useful effect for ions whose lasing transition terminates in, or close to, the ground state. Threshold values for optically induced damage in ED-2 Nd:glass as a function of laser pulse duration. Presently, the most common device involves the use of AℓGaAs diode lasers to pump the Nd3+ absorption band near 810 nm in various hosts, although InGaAs at 943 nm for pumping the Yb3+ ion are receiving increasingly greater interest. In the area of new materials, solid state lasers based on materials with vibronic energy levels will continue to advance. Diode laser pumped solid state lasers are efficient, all solid state sources of coherent optical radiation that have application to laser spectroscopy[1]. A gas laser is the first laser that works on the principle of In practice, some microchip lasers have used one curved mirror to stabilize the cavity. Diode-pumped Cr:LiSAF lasers have been demonstrated and could form the basis of an all-solid-state laser system, although increases in efficiency and power are required. [Crossref] J. Fischer, A. C. Heinrich, S. Maier, J. Jungwirth, D. Brida, and A. Leitenstorfer, “615 fs pulses with 17 mJ energy generated by an Yb:thin-disk amplifier at 3 kHz repetition rate,” Opt. Like any solid-state laser, the microchip laser is formed by a piece of laser material in an optical cavity between two mirrors. For many years, the argon laser has been the dominant laser source in the green. Solid-state lasers may generate output powers between a few milliwatts and (in high-power versions) many kilowatts. The single-shot aerial power density of a two-dimensional diode array is on the order of one kW/cm2. The process of adding impurities to The pump power does not affect the pulse energy. Figure 2. Many Q-switched solid-state lasers have a fairly simple laser resonator with only two mirrors: a flat output coupler and a curved, highly reflecting mirror on the opposite side, through which the pump power can be injected (Figure 3). The linewidth of these sources has decreased from 10KHz for free running standing wave Nd:YAG oscillators[2] to less than 3kHz for nonplanar ring resonator laser oscillators[3]. Since the last edition of this chapter, the prediction of cheaper diode arrays has come true to the tune of roughly a factor ten cost decrease. Here, the laser-active material is a semiconductor, namely the laser diode. Browse All Lasers by Wavelength × Find Lasers by Specification. solid (for example, Nd:YAG, holmium, ruby, alex­ andrite, semiconductor diode), liquid (dye laser), or a gas (for example, argon, krypton, excimer, He-Ne, CO2), In gas lasers, the energy source is generally delivered from an electrical power supply. All solid-state Ti:sapphire lasers are available commercially with TEM00 beam profiles and emission in the single-longitudinal-mode domain, delivering average powers in the watts regime at ∼ 10 kHz. As a consequence, laser ions with a long fluorescent lifetime are easier to diode pump efficiently than ions with a short fluorescent lifetime. This makes laser light highly directional. Neon (Ne) lasers, argon ion lasers, carbon dioxide lasers More detailed design guidelines for passively Q-switched, Lasers and Their Emission Characteristics, Tuning range in the pulsed regime (Walling, Encyclopedia of Materials: Science and Technology, Ultranarrow Linewidth Solid State Oscillators, Encyclopedia of Physical Science and Technology (Third Edition). B: Lasers Opt. Solid-state laser. Thin disk lasers are one of the recent frontiers in solid state lasers. Examples of solid-state lasers that can be operated in a pulsed. wavelength. Introduction to solid-state lasers laser focus world. In this laser, a ruby crystal is used (Nd:glass) and ytterbium-doped glass are used as host The goal of this chapter is to provide the fundamentals of solid-state lasers used in medical applications. Figure 6-2 shows data on the damage threshold for a particular type of Nd:glass that has been used in high-power lasers. ground state absorption bands m m temperature energy is transferred to the crystal (heating) lasing Energy diagram of Nd: By changing the host material the laser wavelength and the thermal properties can be changed. In solids, as in liquids, electrons cannot easily be accelerated by electric fields to excite the laser energy levels of the impurity species so the energy must be fed to the medium via flash lamps or other lasers. The semiconductor laser can be pulsed at varying rate and pulse widths. FIGURE 3. A diode-pumped, Q-switched Nd:YAG microchip laser. Catastrophic damage of the type discussed here is especially important for lasers with very high peak power and short pulse duration. The whole structure is the “laser oscillator,” which gives rise to stimulated emission and laser emission (Zayhowski and Dill 1994) (Fig. Materials doped with rare-earth elements other than neodymium, such as erbium, thulium, and holmium, have led to a diverse assortment of solid-state lasers like Er:glass; Er:YAG; Tm:YAG; Tm:YLF; and Ho,Tm:YAG. Robert L. Byer, in Laser Spectroscopy, 1989. The population inversion is actually maintained in the dopant. M. Eichhorn, “Quasi-three-level solid-state lasers in the near and mid infrared based on trivalent rare earth ions,” Appl. laser light spreads in a small region of space. The damage again has a threshold, below which the effects are small. used as dopants. Due to thermal lasing in solid state lasers, the power loss occurs when the rod gets too hot. 23). tube. produces laser light beam in the near ultraviolet (UV) to The Q-switched operation of green solid state lasers becomes simpler. Solid-state lasers use solids such as glass or crystaline materials as laser mediums, with ions of rare earth elements introduced as impurities via doping. In addition, a solid laser requires much less cooling. synthetic ruby rod (chromium doped aluminum oxide) with mirrors on both ends (one semitransparent) pumped with a helical xenon flashlamp surrounding the rod. are classified into 4 types based on the type of laser In this example, the diameter of the laser rod is smaller than the aperture of the wavefront sensor. In Phys. It is this application that generates the most serious problems of laser damage. More detailed design guidelines for passively Q-switched solid state lasers are given in Spühler et al (1998). Advantages of Semiconductor Lasers. Since the invention of the first ruby laser in 1960, rapid progress has taken place in the development of solid-state lasers. Data on potential materials for solid-state lasers such as alexandrite, GGG, YVO, YLF and others are presented. Efficiency of solid state laser is very low as compared to CO2 lasers. But often, more than one longitudinal mode will be present. solid state laser definition: A laser that uses a glass or crystalline laser medium that is excited by light from an external source. Small fluctuations can destabilize the output. Thus, ordinary light is incoherent. The first solid-state laser – and in fact the first of all lasers – was a pulsed ruby laser, demonstrated by Maiman in 1960 [1]. Because of the easy fabrication and the small amount of material required, the cost can be low. Since frep is a linear function of g0, the pulse repetition rate is proportional to the pump power, and the pulse energy is expected to be approximately constant as a function of the pump power as long as the SESAM is fully saturated. Solid state lasers have lasing material distributed in a solid matrix, e.g., the ruby or neodymium-YAG (yttrium aluminum garnet) lasers. solid-state lasers, light energy is used as the pump source There are four main classes for visible-beam lasers: Class 2, Class 3R, Class 3B and Class 4. The long-wavelength end of the Cr:LiSAF absorption spectrum overlaps the emission of AlxGayIn1 – x – yP semiconductor diodes in the 670 nm region. whereas, in semiconductor lasers, electrical energy is used Types of Lasers There are many types of lasers available for research, medical, industrial, and commercial uses. A solid state laser with short cavity length and a saturable absorber with a small saturation intensity tends to fulfill the condition for passive Q- switching (see Eq. Lasers are often described by the kind of lasing medium they use - solid state, gas, excimer, dye, or semiconductor. The Nd:YAG is often called a YAG laser, harking back to a time when the only good solid-state laser was YAG with Nd 3+ ion minority constituent.

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