Laser Optics

Author: the photonics expert Dr. Rüdiger Paschotta (RP)

Definition: optical elements and systems used with lasers - either in lasers or for transmitting and manipulating laser light

Categories: article belongs to category general optics general optics, article belongs to category laser devices and laser physics laser devices and laser physics

DOI: 10.61835/ypn Cite the article: BibTex plain text HTML Link to this page! LinkedIn

Laser optics essentially means optical elements and systems which are used with lasers – either as parts of lasers or for transmitting and manipulating laser beams or other forms of laser light.

Typical Requirements

Some typical requirements on laser optics, as compared with optics for other purposes such as imaging, are:

Generally, optical losses need to be minimized, particularly for components which are used within laser resonators. Highly reflecting laser errors, for example, typically have reflectivities like 99.9% or higher, so that the total parasitic losses the round-trip in a resonator often remain well below 1%.
The surface quality of laser mirrors, prisms etc. generally needs to be rather high, e.g. with an r.m.s. roughness below λ/10. That, however, is similar for imaging optics such as photographic objectives.
Particularly for use with pulsed lasers with high peak power and pulse energy (mostly Q-switched lasers), laser optics needs to have a high optical damage threshold.
In many cases, good performance is required only at specific optical wavelengths, i.e., at certain laser lines, which are often in the infrared spectral region. Therefore, achromatic optics are often not required. In some cases, however, one requires specified properties at multiple wavelengths, e.g. for a laser wavelength and for frequency-doubled light. Also, some lasers, e.g. ultrashort pulse lasers with particularly short pulse durations, have a substantial optical bandwidth and therefore require optics with suitable broadband properties, for example in terms of reflection bandwidth and chromatic dispersion.

Optics in Lasers

A range of passive optical components is often used in lasers:

Laser mirrors are often used for constructing laser resonators. Most of them are highly reflecting dielectric mirrors, while others have some partial transmissivity for use as output couplers. Dichroic mirrors are often used for injecting pump light into a laser resonator. For ultrafast lasers, one often requires dispersive mirrors.
Lenses are not used much in laser resonators; focusing or defocusing is more often done with curved mirrors to minimize propagation losses and parasitic reflections.
Prisms are more often used outside lasers, but sometimes also inside, particularly for dispersion compensation in ultrafast lasers.
Wavelength tuning is often achieved by inserting some kind of optical filter in a laser resonator – for example, an etalon or a Lyot filter.
Passive mode locking can be done by using a saturable absorber.

Further, some kind of laser gain medium is required, which may for example be a laser crystal, a rare-earth doped fiber, a semiconductor gain chip (e.g. in an external-cavity diode laser or a vertical external-cavity surface-emitting laser) or a gas discharge tube.

In some cases, one requires some kind of optical modulator – for example, an acousto-optic or electro-optic modulator for Q switching or mode locking.

Optics for Laser Light

Outside a laser resonator, laser light often needs to be transported and manipulated, for which different kinds of optical components and systems can be used:

Mirrors are used for redirecting laser light, also for precisely adjusting the beam path. For example, one often uses a pair of mirrors, each one changing the beam direction by approximately 90°. Fine alignment of the beam is possible with micrometers screws on the mirror holders.
Lenses (including cylindrical lenses) are often used for collimating a laser beam, or for modifying its beam radius, or for tight beam focusing. Sometimes, such things are done with complete assemblies like beam collimators, beam expanders and focusing objectives, which may contain multiple lenses.
Anamorphic prism pairs may be used for converting elliptical beam profiles into circular ones.
Mode cleaners can be used for improving the beam quality.
Polarizing or non-polarizing beam splitters can be used for obtaining multiple beams or for guaranteeing linear polarization states.
Waveplates can be used for manipulating the polarization state – for example, for rotating the polarization direction or converting linearly polarized light into circularly polarized light.
Optical filters may be used to remove unwanted spectral components – for example, residual laser light after a frequency doubler.
Neutral density filters and other optical attenuators can be used to reduce the optical power. There are also so-called noise eaters which automatically adjust the attenuation such as to obtain a constant output power.
Faraday isolators are used for protecting a laser source against back-reflected light.
Various kinds of optical modulators may be inserted, for example intensity or phase modulators or optical switches.
In some cases, diffractive optics are used, for example for splitting a beam into a large number of beams with a single optical component.
Unwanted beams may be sent into beam dumps for safely converting the optical energy into heat.
There are scanning lenses for laser scanners, sending laser beams in variable directions.

More to Learn

lasers optics laser mirrors

Suppliers

The RP Photonics Buyer's Guide contains 113 suppliers for laser optics. Among them:

Sinoptix

We offer competitive laser optics solutions – laser cavity mirrors, total reflecting mirrors, CO₂ laser mirrors, scanning mirrors, laser focusing lenses, laser windows and filters. High quality coatings with advanced damage threshold.

Shanghai Optics

Optical components are used in a wide range of applications, such as microscopy, imaging, life science, testing and measurement. Shanghai Optics custom made optical components are designed with specific substrates, custom coatings to optimize the performance in UV, visible, SWIR, MWIR, LWIR wavelength. With the help of state-of-the-art metrology, Shanghai Optics is committed to high quality and top performance optical components.

Knight Optical

Knight Optical has a range of available laser optical components from laser mirrors exhibiting minimal GDD and high LIDT, to lenses manufactured from zinc selenide ideal for CO₂ lasers. Our thin film polarisers exhibit > 99.9% reflection in s-polarisation with a separated > 98% p-polarised transmission beam. We also excel at working with our customers to provide custom optical components meeting their design specifications, including output couplers, resonator mirrors, and wavelength separators.

Artifex Engineering

Artifex Engineering's laser optics portfolio includes Pockels cells, polarizers, laser mirrors, prisms, lenses, windows, and beamsplitters. Visit our product pages for more information. We look forward to your inquiry.

PowerPhotonic

PowerPhotonics freeform direct write manufacturing process can allow for completely freeform and custom micro-optics to be designed and manufactured without any costly set up fees or masks. The use of high-quality fused silica leads to micro optics with high power handling capabilities, while delivering very low scatter and high performance.

EKSMA OPTICS

EKSMA Optics manufactures and sells a wide range of precision optical components and optical systems, mostly for high power laser applications.

Laserton

Laserton can provide various types of laser optics, including mirrors, beam splitters, windows, prisms and lenses.

few-cycle

few-cycle offers state-of-the-art components (dispersive and non-dispersive mirrors, windows, wedges) that enable achieving and preserving the bandwidth-limited duration of few-cycle pulses with central wavelengths ranging from the visible to the near infrared. Our R & D projects pave the way to implementing dispersion management techniques for ultrashort pulses with average powers up to 200 W.

Avantier

Our laser optics include all the optical elements and optical systems used within lasers, or for manipulating—or transmitting—laser light. Laser optics components have more stringent requirements on surface quality and coating when comparing with standard imaging optics.

OPTOMAN

OPTOMAN manufactures highly customized and application-optimized laser optics for high power and ultrafast lasers. We are ready to design, develop and manufacture cost-effective yet advanced, high accuracy and repeatability ion beam sputtered coatings and laser optical components.

Standard in-stock IBS coated optics can be found in OPTOSHOP.

IRD Glass

IRD has a strong presence in the laser optics OEM market, providing cavity reflectors for the solid-state laser industry, HLDT/HR steering mirrors, splatter shields, precision spacers and tooling, beamsplitters, custom corner cubes, filters and many other custom components. IRD Glass and IRD Ceramics work with all types of materials, from fused silica to sapphire, from filter glass to chalcogenides, doped glass to crystals.

Shalom EO

Shalom EO’s catalogue of laser optics including, where Shalom EO keep a rigorous quality control to ensure precise manipulation of laser beams:

laser lenses, CO₂ laser focusing lenses
laser windows (UV, VIS, NIR and IR windows made of MgF₂, CaF₂ or UV fused silica, optical glass, Ge, ZnSe, sapphire, silicon, etc.)
laser mirrors (with dielectric coating, enhanced Al coatings, protective silver or gold coating, low GDD coatings), high power laser mirrors with LIDT of >20 J/cm² @ 1064 nm, 10 ns, 10 Hz pulses
laser prisms (including right angle prisms, corner cube retroreflectors, wedge, Brewster angle and equilateral prisms etc.)
laser filters
polarizers, beamsplitters, and waveplates and retarders
optical components for femtosecond lasers

Through the use of cutting-edge instruments, including Zygo interferometers and PerkinElmer Lambda 1050+ spectroscopes, Shalom EO maintains the unwavering quality of our optical components.

Megawatt Lasers

MegaWatt Lasers has a large inventory of HR and OC mirrors for 1064 nm, 2.1 μm and 2.94 μm wavelengths. We also can assist in specification of optics for these wavelengths.

UM Optics

UM Optics can provide flat lenses, cylindrical lenses, spherical lenses, aspheric lenses and prisms, laser protection windows, mirrors, beam concentrators, output couplers, focussing lenses, beam splitters and scanning mirrors. We offer customized services for laser lenses to meet the needs of different customers.

Diameters: 0 to 350 mm, Ra < 3 nm, PV < 0.2 μm.

Materials: quartz, sapphire, Si, Ge, ZnSe, glass, copper, aluminium and others.

Edmund Optics

Edmund Optics offers a wide variety of laser optics, including laser lenses, laser mirrors, laser filters, along with a variety of other components designed for laser use. Laser lenses are designed to focus, homogenize, or shape laser beams. Laser mirrors are ideal for beam steering applications. Laser filters transmit or reflect a portion of the laser light. Laser windows are used to transmit designated wavelengths or protect sensitive components or work areas from stray light.

LASEROPTIK

Laser optics are the core of LASEROPTIK's business. We offer dielectric coatings for a wide range of optical components.

Perkins Precision Developments

Perkins Precision Developments (PPD) manufactures high energy laser mirrors and precision optics for both prototype and volume OEM requirements. We also offer custom Ion Beam Sputtered (IBS) thin film coatings for visible to near-infrared wavelengths on customer supplied substrates. PPD utilizes IBS coating technology because it is ideal for complex spectral designs, high power lasers and applications where it is critical to minimize losses from absorption and scatter.

Typical HEL mirror coatings include dielectric low-loss high reflectors (HR), multi-wavelength high reflectors, dichroic mirrors, trichroic mirrors, partial beam splitting mirrors and 45 degree thin film plate polarizers.

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