RP Photonics logo
RP Photonics
Encyclopedia
Consulting Software Encyclopedia Buyer's Guide

Short address: rpp-con.com

Dr. Paschotta, the founder of RP Photonics, supports your R & D with his deep expertise. Save time and money with efficient support!

Short address: rpp-soft.com

Powerful simulation software for fiber lasers and amplifiers, resonator design, pulse propagation and multilayer coating design.

Short address: rpp-enc.com

The famous Encyclopedia of Laser Physics and Technology provides a wealth of high-quality scientific and technical information.

Short address: rpp-bg.com

In the RP Photonics Buyer's Guide, you easily find suppliers for photo­nics products. As a supp­lier, you can profit from enhanced entries!

Learn on lasers and photonics every day!
VL logo part of the
Virtual
Library

Gain Media

<<<  |  >>>  |  Feedback

Buyer's Guide

The ideal place to find suppliers for photonics products: high-quality information, simple and fast, respects your privacy!

63 suppliers for laser crystals and glasses are listed.

Among them:

Altechna UAB

nonlinear, laser and Q-switching gain media: BBO, LBO, CLBO, AGS, Ti:Sa, Yb:YAG, Yb:KGW/KYW and others

Your are not yet listed? Get your entry!

Ask RP Photonics for advice on any aspects of laser gain media.

Definition: media for laser amplification

German: Verstärkungsmedien

Categories: optical amplifiers, lasers, optical materials

How to cite the article

Within the context of laser physics, a laser gain medium is a medium which can amplify the power of light (typically in the form of a light beam). Such a gain medium is required in a laser to compensate for the resonator losses, and is also called an active laser medium. It can also be used for application in an optical amplifier. The term gain refers to the amount of amplification.

As the gain medium adds energy to the amplified light, it must itself receive some energy through a process called pumping, which may typically involve electrical currents (electrical pumping) or some light inputs (→ optical pumping), typically at a wavelength which is shorter than the signal wavelength.

Types of Laser Gain Media

There are a variety of very different gain media; the most common of them are:

Compared with most crystalline materials, ion-doped glasses usually exhibit much broader amplification bandwidths, allowing for large wavelength tuning ranges and the generation of ultrashort pulses. Drawbacks are inferior thermal properties (limiting the achievable output powers) and lower laser cross sections, leading to a higher threshold pump power and (for passively mode-locked lasers) to a stronger tendency for Q-switching instabilities. See the article on laser crystals versus glasses for more details.

The doping concentration of crystals, ceramics and glasses often has to be carefully optimized. A high doping density may be desirable for good pump absorption in a short length, but may lead to energy losses related to quenching processes, e.g. caused by upconversion via clustering of laser-active ions and energy transport to defects.

Important Physical Effects

In most cases, the physical origin of the amplification process is stimulated emission, where photons of the incoming beam trigger the emission of additional photons in a process where e.g. initially excited laser ions enter a state with lower energy. Here, there is a distinction between four-level and three-level gain media.

A less frequently used amplification process is stimulated Raman scattering, involving the conversion of some higher-energy pump photons into lower-energy laser photons and phonons (related to vibrations e.g. of the crystal lattice).

For high levels of input light powers, the gain of a gain medium saturates, i.e., is reduced. This naturally follows from the fact that for a finite pump power an amplifier cannot add arbitrary amounts of power to an input beam. In laser amplifiers, saturation is related to a decrease in population in the upper laser level, caused by stimulated emission.

Thermal effects can occur in gain media, because part of the pump power is converted into heat. The resulting temperature gradients and also subsequent mechanical stress can cause lensing effects, distorting the amplified beam. Such effects can spoil the beam quality of a laser, reduce its efficiency, and sometimes even destroy the gain medium (thermal fracture).

Relevant Physical Properties of Laser Gain Media

A great variety of physical properties of a gain medium can be relevant for use in a laser. The desirable properties include:

Note that in many situations there are partially conflicting requirements. For example, a very low quantum defect is not compatible with four-level behavior. A large gain bandwidth typically means that laser cross sections are smaller than ideal, and that the quantum defect cannot be very small. Disorder in solid-state gain media increases the gain bandwidth, but also reduces the thermal conductivity. A short pump absorption length can be advantageous, but also tends to exacerbate thermal effects.

It is apparent that different situations lead to very different requirements on gain media. For this reason, a very broad range of gain media will continue to remain important for applications, and making the right choice is essential for constructing lasers with optimum performance.

See also: gain, gain bandwidth, gain saturation, laser transitions, quantum defect, laser crystals, rare-earth-doped gain media, transition-metal-doped gain media, ceramic gain media, laser crystals versus glasses, solid-state lasers, four-level and three-level gain media, amplifiers, transition cross sections, doping concentration

How do you rate this article?

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent
Comments:

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you like our website, you may also want to get our newsletters!

cover of SPIE Field Guide cover of SPIE Field Guide cover of SPIE Field Guide

Dr. Paschotta, author of this encyclopedia, has also published three books in the SPIE Field Guide series:

- Field Guide to Lasers

- Field Guide to Laser Pulse Generation

- Field Guide to Optical Fiber Technology

You can order these books on the SPIE website – just click on one of the images.

arrow

RP Fiber Power – the versatile Fiber Optics Software

An Amazing Tool

RP Fiber Power software

This amazing tool is extremely helpful for the development of passive and active fiber devices.

ASE

Watch our quick video tour!

Single-mode and Multi­mode Fibers

fibers

Calculate mode properties such as

  • amplitude distributions (near field and far field)
  • effective mode area
  • effective index
  • group delay and chromatic dispersion

Also calculate fiber coupling efficiencies; simulate effects of bending, nonlinear self-focusing or gain guiding on beam propagation, higher-order soliton propagation, etc.

Arbitrary Index Profiles

A fiber's index profile may be more complicated than just a circle:

special fibers

Here, we "printed" some letters, translated this into an index profile and initial optical field, propagated the light over some distance and plotted the output field – all automated with a little script code.

Fiber Couplers, Double-clad Fibers, Multicore Fibers, …

fiber devices

Simulate pump absorption in double-clad fibers, study beam propagation in fiber couplers, light propagation in tapered fibers, analyze the impact of bending, cross-saturation effects in amplifiers, leaky modes, etc.

Fiber Amplifiers

fiber amplifier

For example, calculate

  • gain and saturation characteristics (for continuous or pulsed operation)
  • energy transfers in erbium-ytterbium-doped amplifier fibers
  • influence of quenching effects, amplified spontaneous emission etc.

in single amplifier stages or in multi-stage amplifier systems, with double-clad fibers, etc.

Fiber-optic Telecom Systems

eye diagram

For example,

  • analyze dispersive and nonlinear signal distortions
  • investigate the impact of amplifier noise
  • optimize nonlinear management and the placement of amplifiers

Find out in detail what is going on in such a system!

Fiber Lasers

fiber laser

For example, analyze and optimize the

  • power conversion efficiency
  • wavelength tuning range
  • Q switching dynamics
  • femtosecond pulse generation with mode locking

for lasers based on double-clad fiber, with linear or ring resonator, etc.

Ultrafast Fiber Lasers and Amplifiers

fiber laser

For example, study

  • pulse formation mechanisms
  • impact of nonlinearities and chromatic dispersion
  • parabolic pulse amplification
  • feedback sensitivity
  • supercontinuum generation

Apply any sequence of elements to your pulses!

… and even Bulk Devices

regenerative amplifier

For example, study

  • Q switching dynamics
  • mode-locking behavior
  • impact of nonlinearities and chromatic dispersion
  • influence of a saturable absorber
  • chirped-pulse amplification
  • regenerative amplification

RP Fiber Power is an extremely versatile tool!

Mode Solver

fiber modes

For example, calculate

  • amplitude and intensity profiles
  • effective mode areas
  • cut-off wavelengths
  • propagation constants
  • group velocities
  • chromatic dispersion

All this is calculated with high efficiency!

Beam Propagation

beam propagation

Propagate optical field with arbitrary wavefronts through fibers. These may be asymmetric, bent, tapered, exhibit random disturbances, etc.

See our demo video for numerical beam propagation.

Laser-active Ions

level scheme

Work with the standard gain model, or define your own level scheme!

Can include different ions, energy transfers, upconversion and quenching effects, complicated pumping schemes, etc.

Multiple Pump and Signal Waves, ASE

optical channels

Define multiple pump and signal waves and many ASE channels – each one with its own transverse intensity profile, loss coefficient etc.

The power calculations are highly efficient and reliable.

Simple Use and High Flexibility Combined

For simpler tasks, use convenient forms:

signal parameters

Script code is automatically generated and can then be modified by the user. A powerful script language gives you an unparalleled flexibility!

High-quality Documentation and Competent Support

The carefully prepared comprehensive documentation includes a PDF manual and an interactive online help system.

Competent technical support is provided: the developer himself will help you and make sure that any problem is solved!

Our support is like included technical consulting.

Boost your competence, efficiency and creativity!

  • Stop fishing in the dark! Develop a clear quantitative understanding of your devices.
  • Explore the effects of possible design changes on your desk.
  • That way, get most efficient in the lab.
  • Find optimized solutions efficiently, minimizing time to market.
  • Get new ideas by playing with your models.

Efficiency and success of
R & D are not a matter of chance.

See our detailed description with many case studies!

Contact us to get a quotation!

– Show all banners –

– Get your own banner! –