定义：
发射蓝光的激光器。

这里主要讨论发射光在蓝光和紫光光谱范围内的激光器，即发射光波长在400-500nm之间。在这一波段激光增益介质是有限的，并且其性能没有红外光谱区域的好。 

蓝光激光器的种类 
下面几种是最常见的蓝光激光器： 

1. 蓝光激光二极管，通常采用的是氮化镓（GaN）或者其它与其相关的材料（InGaN），辐射波长范围在400-480nm，较难实现高输出功率和长寿命。输出功率可以达到几十到几百毫瓦。目前，这种器件只有很少量的用于商用，比较先进的是Nichia公司，其次是索尼和夏普。这一领域的发展非常迅速，有理由相信蓝光激光二极管会持续在性能和寿命指数上有长足进步，并且能够更加广泛的应用。一个新的发展方向是蓝光VCSELs。 
2. 采用光纤或者晶体材料的掺铥或者掺镨上转换激光器辐射480nm的光，通常输出功率在几十毫瓦，并且光束质量很好。经过发展今后可能得到几百毫瓦甚至几瓦的功率。 
3. 氦镉激光器（也是气体激光器）可以辐射441.6nm的蓝光区域的光，光束质量很好，输出功率为几百毫瓦。 
4. 蓝光或者紫光也可以通过将波长在800-1000nm的激光通过倍频过程（在激光器谐振腔或者腔内）产生。最常用的是掺钕激光器，例如，钕钇铝石榴石激光器发射波长为946nm，钕钒酸钇发射波长为914nm，Nd:YAlO3发射波长为930nm。通常用于倍频的非线性晶体材料为LBO，BiB3O6，KNbO3，以及KTP和 LiTaO3。输出功率可以达到几瓦，即使是在单频工作的情况下，光束质量很好，然而比1微米激光器要稍微困难一些。除了激光器，还可以采用一个光学振荡谐振腔。 
5. 高功率光学泵浦VECSELs也是非常好的用于倍频的激光光源，输出功率为几瓦甚至几十瓦。需要注意的是，还有一些半导体激光器，例如大面积激光二极管也可以产生合适的波长，但是由于其线宽更宽，光束质量较差不适用于倍频。然而有些二极管激光器可以得到几十毫瓦的倍频光。 
6. 利用氩等离子体的激光器放大的氩离子激光器也是非常好的激光光源。然而其发射绿光波长514nm可以达到最大的输出功率，也可以发射几瓦特的488nm的光，在458、477和497nm处较弱。任一情况下，这种激光器的功率效率都非常低，因此为了得到几瓦特蓝光输出需要消耗几十千瓦的电能，并且也需要较大的冷却装置。还有更小的空气冷却氩离子激光器管，为了得到几十毫瓦需要消耗几百瓦特。 

若波长小于400nm，人眼的灵敏度迅速下降，这属于紫外光区域。需要注意的是，在400nm附近或者稍高于400nm的波长处，视网膜可能通过光化效应而受到损伤，即使光强看起来并不是很高。 

蓝光和紫光激光器的应用 
蓝光和紫光激光器可以用于干涉仪，激光打印和数码冲印，数据记录，激光显微镜，激光投影显示，流式细胞仪以及光谱测量中。记录数据是蓝光激光二极管发展的主要动力。大多数情况下，蓝光和紫光激光器的发展受短波长激光器发展的推动，因此能够实现很强的聚焦或者在成像应用中分辨非常精细的结构。

Definition: lasers emitting blue light

More general term: visible lasers

This article deals with lasers emitting in the blue and violet spectral region, i.e., with a wavelength roughly around 400–500 nm. Note that even lasers clearly emitting in the violet spectral region are often called blue lasers instead of violet lasers.

The choice of laser gain media for such wavelengths is limited, and the achievable performance is typically not as good as in, e.g., the infrared spectral region. However, substantial technical progress has lead to a choice of blue and violet lasers, including many commercial devices, which is suitable for a wide range of applications.

Types of Blue Lasers

The following types of blue lasers are the most common:

• Blue laser diodes [4], based on gallium nitride (GaN) or related materials (e.g. InGaN) and emitting around 400–480 nm, have been developed quite successfully, now offering substantially better output powers and device lifetimes than green diode lasers. Output powers can now be up to the order of 10 W for a blue broad-area laser diode, for example, and by combining many of such laser diodes, fiber-coupled diode lasers with hundreds of watts or more out of one multimode fiber have become commercially available. One may also generate of the order of 100 W with a diode bar. Another development is that of blue-emitting VCSELs [11].
• Thulium-doped or praseodymium-doped upconversion lasers based on fibers or bulk crystals can emit around 480 nm, typically with some tens of milliwatts of output power and with good beam quality. Further development for powers of hundreds of milliwatts or even multiple watts appears to be feasible.
• Blue or violet light can also be generated by frequency doubling (external to the laser resonator or intracavity) the output of lasers emitting around 800–1000 nm. Most frequently used are neodymium-doped lasers, e.g. Nd:YAG emitting at 946 nm (for 473 nm), Nd:YVO₄ at 914 nm (for 457 nm), and Nd:YAlO₃ at 930 nm (for 465 nm). Common nonlinear crystal materials for frequency doubling with such lasers are LBO, BiB₃O₆ (BIBO), KNbO₃, as well as periodically poled KTP and LiTaO₃. Output powers of multiple watts can be obtained, even with single-frequency operation and high beam quality, although less easily than with 1-μm lasers. Instead of a laser, an optical parametric oscillator may be used.
• High-power optically pumped VECSELs are also very attractive laser sources for frequency doubling with several watts or even tens of watts of output power. Note that other kinds of semiconductor lasers, such as broad area laser diodes, are available with suitable wavelengths, but are less suitable for frequency doubling due to a typically broader linewidth and poor beam quality. There are some diode lasers, however, which deliver some tens of milliwatts of frequency-doubled light.
• Helium–cadmium lasers (which are gas lasers) can emit hundreds of milliwatts in the blue region at 441.6 nm, with high beam quality.
• Argon ion lasers, based on laser amplification in an argon plasma (made with an electrical discharge), are fairly powerful light sources for various wavelengths. While the highest power can be achieved in green light at 514 nm, significant power levels of several watts are also available at 488 nm, apart from some weaker lines e.g. at 458, 477 and 497 nm. In any case, the power efficiency of such lasers is very poor, so that tens of kilowatts of electric power are required for multi-watt blue output, and the cooling system has corresponding dimensions. There are smaller tubes for air-cooled argon lasers, requiring hundreds of watts for generating some tens of milliwatts.

Eye Hazards

For wavelengths below ≈ 400 nm, the eye's sensitivity (i.e. its ability to detect small light levels) sharply declines, and one enters the region of ultraviolet light. (See also the article on ultraviolet lasers.) Note that even for wavelengths around or slightly above 400 nm, the retina can be damaged via photochemical effects even for intensity levels which are not perceived as very bright.

Applications of Blue and Violet Lasers

Blue and violet lasers are used e.g. in interferometers, for laser printing (e.g. exposure of printing plates) and digital photofinishing, data recording (Blu-ray Disc, holographic memory), in laser microscopy, in laser projection displays (as part of RGB sources), in flow cytometry, and for spectroscopic measurements. Direct diode laser applications also become more and more feasible due to the performance enhancement of blue laser diodes.

Data recording is the major driver for the development of blue and violet laser diodes; the short emission wavelength allows for an improved density of storage.

In most cases, the use of blue and violet lasers is motivated by the relatively short wavelengths, which allows for strong absorption in many materials, for tight focusing, or for resolving very fine structures in imaging applications.