Solid-state Lasers
Author: the photonics expert Dr. Rüdiger Paschotta (RP)
Acronym: SSL
Definition: lasers based on solid-state gain media (usually ion-doped crystals or glasses)
Category: 
Related: doped insulator lasersall-solid-state laserslaserslaser gain medialaser crystalscomposite laser crystalslaser glassesrare-earth-doped laser gain mediatransition-metal-doped laser gain mediaYAG lasersfiber lasers versus bulk lasersdiode-pumped lasers
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What are Solid-state Lasers?
Solid-state lasers are lasers based on solid-state gain media such as crystals or glasses doped with rare earth or transition metal ions. Semiconductor lasers are also solid-state lasers, but they are not always meant with that term.
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.
Solid-state lasers may generate output powers between a few milliwatts and (in high-power versions) many kilowatts.
The first solid-state laser — and in fact the first of all lasers — was a pulsed ruby laser, demonstrated by Maiman in 1960 [1]. Later on, however, other solid-state gain media were preferred because of their superior performance. A major problem with ruby is its pronounced three-level nature.
Optical Pumping
Many solid-state lasers are optically pumped with flash lamps or arc lamps. Such pump sources are relatively cheap and can provide very high powers. However, they lead to a fairly low power efficiency, moderate lifetime, and strong thermal effects such as thermal lensing in the gain medium.
Laser diodes are now most often used for pumping solid-state lasers. Such diode-pumped solid-state lasers (DPSS lasers, also called all-solid-state lasers) have many advantages, in particular a compact setup, long lifetime, and often very good beam quality.
Energy Storage
The laser transitions of rare-earth or transition-metal-doped crystals or glasses are normally weakly allowed transitions, i.e., transitions with very low oscillator strength, which leads to long upper-state lifetimes and consequently to good energy storage, with upper-state lifetimes of microseconds to milliseconds. For example, a laser crystal pumped with 10 W of power and having an upper-state lifetime of 1 ms can store an energy of the order of 10 mJ.
Although energy storage is beneficial for nanosecond pulse generation (see below), it can also lead to unwanted spiking phenomena in continuous-wave lasers, e.g. when the pump source is switched on.
Pulse Generation
The long upper-state lifetimes make solid-state lasers very suitable for Q-switching: the laser crystal can easily store an amount of energy which, when released in the form of a nanosecond light pulse, leads to a peak power which is orders of magnitude above the achievable average power. Bulk lasers can thus easily achieve millijoule pulse energies and megawatt peak powers.
In mode-locked operation, solid-state lasers can generate ultrashort pulses with durations measured in picoseconds or femtoseconds (minimum: ≈ 5 fs, achieved with Ti:sapphire lasers). Some passively mode-locked solid-state lasers have a tendency for Q-switching instabilities, but these can usually be suppressed with suitable measures.
Wavelength Tuning
In terms of their potential for wavelength tuning, different types of solid-state lasers differ considerably. Most rare-earth-doped laser crystals, such as Nd:YAG and Nd:YVO4, have a fairly small gain bandwidth of the order of 1 nm or less, so that tuning is possible only within a rather limited range. On the other hand, tuning ranges of tens of nanometers and more are possible with rare-earth-doped glasses, and particularly with transition-metal-doped crystals such as Ti:sapphire, Cr:LiSAF and Cr:ZnSe (→ vibronic lasers).
Typical Solid-state Lasers
Examples of different types of solid-state lasers are:
- Small diode-pumped Nd:YAG (→ YAG lasers) or Nd:YVO4 lasers (→ vanadate lasers) often operate with output powers between a few milliwatts (for miniature setups) and a few watts. Q-switched versions generate pulses with durations of a few nanoseconds, microjoule pulse energies and peak powers of many kilowatts. Intracavity frequency doubling can be used for green output.
- Single-frequency operation, typically achieved with unidirectional ring lasers (e.g. NPROs = nonplanar ring oscillators) or with microchip lasers, allows for operation with very small linewidth in the lower kilohertz region.
- Larger lasers in side-pumped or end-pumped configurations (see above), having the geometry of rod lasers, slab lasers or thin-disk lasers, are suitable for output powers up to several kilowatts. Particularly thin-disk lasers can still offer very high beam quality, and also a high power efficiency.
- Q-switched Nd:YAG lasers are still widely used in lamp-pumped versions. Pulsed pumping allows for high pulse energies, whereas the average output powers are often moderate (e.g. a few watts). The cost of such lamp-pumped lasers is lower than for diode-pumped versions with similar output powers.
- Fiber lasers are a special kind of solid-state lasers, with a high potential for high average output power, high power efficiency, high beam quality, and broad wavelength tunability. See also the articles on fiber lasers versus bulk lasers and on high-power fiber lasers and amplifiers.
Frequently Asked Questions
This FAQ section was generated with AI based on the article content and has been reviewed by the article’s author (RP).
What is a solid-state laser?
A solid-state laser is a laser that uses a solid gain medium, such as a crystal or glass doped with ions. This category includes bulk lasers and fiber lasers, while semiconductor lasers are often treated separately.
What is a DPSS laser?
A DPSS laser is a diode-pumped solid-state laser. It uses highly efficient laser diodes as the pump source, which results in a compact setup, long lifetime, and often excellent beam quality.
Why are solid-state lasers well suited for generating powerful pulses via Q-switching?
The gain media in solid-state lasers typically have a long upper-state lifetime, allowing for significant energy storage. This stored energy can be released in a short, intense pulse using the Q-switching technique, achieving very high peak powers.
Are all solid-state lasers wavelength-tunable?
The tuning potential varies. Some, like Nd:YAG, have a very narrow gain bandwidth and limited tunability. Others, particularly vibronic lasers with transition-metal-doped crystals like Ti:sapphire, offer very broad wavelength tuning ranges.
What are some common types of solid-state lasers?
Common types include Nd:YAG and Nd:YVO4 lasers, high-power thin-disk lasers and slab lasers, and fiber lasers. The first laser ever built, the ruby laser, was also a solid-state laser.
Suppliers
Sponsored content: The RP Photonics Buyer's Guide contains 138 suppliers for solid-state lasers. Among them:
The Stuttgart Instruments Primus is an ultrafast (fs) mode-locked oscillator, based on the solid-state technology. It provides a high average output power combined with a superior low noise level (shot noise limit above 300 kHz) and an excellent long-term stability.
The solid-state technology with 1040 nm central wavelength enables the excellent long-term stability by providing several watts of output power at 40 MHz pulse repetition rate and 450 fs pulse duration. Its superior low noise level reaches the shot noise limit above 300 kHz. In combination with the stability and output power, it enables ultrasensitive measurements and makes the Primus perfectly suited as pump source for frequency converters like the Stuttgart Instruments Alpha. The entire system is encapsulated in a solid CNC-cut and water-cooled housing, thus reaching excellent robustness against external perturbations.
HÜBNER Photonics specializes in high-performance diode-pumped solid state lasers, featuring exceptional wavelength and power stability, along with minimal noise levels. Our product range includes:
- Cobolt 04-01, 05-01, and 08-01 Series: Solid state lasers
- Cobolt Skyra: Multi-line laser system
- C-WAVE: Tunable laser system
For detailed specifications and applications, visit our website.
Bright Solutions offers a range of diode-pumped solid-state lasers, including
- Wedge — nanosecond Q-switched lasers for 266, 355, 532, 1064, 1570, 3100 nm (also multi-wavelength configurations), used e.g. for atmospheric LIDAR, monitoring, glass machining or lithography
- Onda — compact monolithic nanosecond Q-switched lasers for 266, 355, 532 or 1064 nm, used e.g. for lens marking, plastic marking or intravolume glass marking
- Sol — compact Q-switched lasers for 355, 532 or 1064 nm, up to 200 kHz, used e.g. for automotive fabrication, electronic machining, ID card writing and other industrial applications
- Vento — sub-nanosecond MOPA lasers with pulse durations down to 500 ps, up to 200 kHz, up to 100 W average power at 1064 nm or 50 W at 532 nm, e.g. for LIDAR or PCB microprocessing
- Aero — high energy lasers with up to 200 mJ at 1064 nm, 100 mJ at 532 nm, multi-wavelength configurations, custom beam shaping, application e.g. in atmospheric LIDAR, LIBS or nonlinear spectroscopy
- BDL and BFD — fiber-coupled diode laser modules with up to 200 W cw (or 400 W quasi-cw) in a 200-μm core fiber, e.g. for pumping of solid-state and fiber lasers, material processing or illumination; pulsed models are available
- NPS — narrowband picosecond lasers for applications like OPO pumping, Raman or fluorescence spectroscopy and multimodal imaging
- ONE DPSS — miniaturized Q-switched lasers with up to 200 μJ and down to 3 ns, e.g. for atmospheric LIDAR and laser marking on plastics
GWU-Lasertechnik provides all-solid-state tunable laser solutions. We have more than 30 years of experience in lasers, non-linear optics and manufacturing. The sophisticated optical and mechanical design of our devices ensure excellent performance, highest reliability and longest lifetime. Our rugged all-solid-state Laser technology does not require any consumable supplies and is thus providing most convenient usability, longest lifetime and excellent total costs of ownership. GWU’s widely tunable laser sources cover the spectral range from the deep-UV at < 190 nm to the IR at > 2700 nm continuously to serve even most demanding applications in science and industry.
Edmund Optics offers a wide range of diode laser sources, including machine vision lasers, life science lasers, metrology lasers, industrial and point lasers, and material processing lasers.
Radiantis broadly tunable lasers are based on solid-state technology. Femtosecond and picosecond pulses as well as continuous-wave (CW) temporal regimes are provided with automatic tuning across the UV, visible and IR.
CNI offers a wide range of all-solid-state lasers not only concerning wavelengths, but also in terms of features, including single frequency lasers, narrow linewidth lasers, low noise lasers, high power and high energy lasers, mode-locked picosecond lasers and Q-switched lasers.
RPMC Lasers offers the widest selection of solid-state lasers in North America. From ≈ 1500 standard products to full customization capabilities, we are sure to have what you need: pulsed and CW sources ranging in wavelength from the UV through the LWIR regimes. Pulsed lasers include DPSS lasers, fiber lasers, microlasers/microchip Lasers, ultrafast lasers, and more. Single- & multimode CW DPSS lasers, modules & LD modules are available in both fiber-coupled and free space configurations, as well as gas and fiber lasers, line modules, and many laser diode types, including free space & fiber-coupled diodes, bars & stacks, wavelength stabilized laser diodes, quantum cascade laser diodes, and more! Let RPMC help you find the right laser today!
Lasers from Teem Photonics are all air-cooled diode-pumped solid-state lasers, which are passively Q-switched to generate sub-nanosecond pulses, and in some cases combined with a fiber amplifier. Due to nonlinear frequency converters, available emission wavelengths are 1064 nm, 532 nm, 355 nm, 266 nm and 213 nm.
Monocrom offers diode-pumped solid state lasers for medical, material processing, LiDAR and spectroscopy applications as well as for laser pumping:
- LQ-527-12: a frequency-doubled Nd:YLF laser emitting up to 1 mJ at 527 nm
- Multi-Path 532: a photocoagulation laser emitting up to 8 W cw or 15 W qcw at 532 nm
- CiOM lasers emitting nanosecond pulses at 526.5 nm
Training: RP personally offers staff training courses on many topics in laser technology — tailored to your needs. Boost the competence and productivity of your team within just a few days!
Software: For various areas in laser technologies, RP Photonics also offers powerful simulation software, such as RP Fiber Power for simulating fiber amplifiers and lasers.
Lumibird nanosecond Q-switched Nd:YAG lasers are well known for their ruggedness and versatility. From 5 mJ to 2.3 J at 1064 nm, from single pulse to 400 Hz, they can be diode-pumped (compactness, ease of use) or flashlamp-pumped (high energy), and are available at 532 nm, 355 nm, 266 nm and 1.5 µm. Double pulse models are also proposed for applications in fluid mechanics (PIV).
MegaWatt Lasers Inc. offers CTH:YAG and Er:YAG resonators. These are flash lamp pumped and water cooled. They are optimized for energy and repetition rate. The CTH:YAG resonator is able to generate 4-J pulses at a repetition rate of 10 Hz, while the Er:YAG resonator reaches 3 J at also 10 Hz. Both allow for adjustable pulse widths.
Bibliography
| [1] | T. H. Maiman, “Stimulated optical radiation in ruby”, Nature 187, 493 (1960) (first experimental demonstration of a laser); doi:10.1038/187493a0 |
| [2] | R. L. Byer, “Diode laser-pumped solid-state lasers”, Science 239, 742 (1988); doi:10.1126/science.239.4841.742 |
| [3] | G. Huber, C. Kränkel and K. Petermann, “Solid-state lasers: status and future”, J. Opt. Soc. Am. B 27 (11), B93 (2010); doi:10.1364/JOSAB.27.000B93 |
| [4] | D. C. Hanna and W. A. Clarkson, “A review of diode-pumped lasers”, in Advances in Lasers and Applications (eds. D. M. Finlayson and B. Sinclair), pp. 1–18, Taylor & Francis, New York(1999) |
| [5] | W. Koechner, Solid-State Laser Engineering, 6th edn., Springer, Berlin (2006) |
| [6] | A. Sennaroglu (ed.), Solid-State Lasers and Applications, CRC Press, Boca Raton, FL (2007) |
| [7] | R. Paschotta, Field Guide to Lasers, SPIE Press, Bellingham, WA (2007) |
| [8] | R. Paschotta, “Operation regimes of solid-state lasers”, chapter in Handbook of solid-state lasers: Materials, systems and applications, editors: B. Denker, and E. Shklovsky, Woodhead Publishing (2013), ISBN 0 85709 272 3 |
(Suggest additional literature!)
Questions and Comments from Users
2022-06-26
In some real solid-state continuous-wave lasers it is possible to observe mode hopping. What is the reason of that?
The author's answer:
See the article on mode hopping.
2022-06-24
Could you please explain why most solid state laser can generate pulses shorter than the average lifetime of the excited state.
The author's answer:
The upper-state lifetime is not relevant because it is the lifetime in the absence of light. With a short intense pulse, you can extract the stored energy within a much shorter time.