Oral Roberts's successful use of television as a medium to gain a wider audience led others to follow suit.

The back-formed verb to lase is frequently used in the field, meaning " to produce laser light ," especially in reference to the gain medium of a laser ; when a laser is operating it is said to be " lasing.

A laser consists of a gain medium, a mechanism to supply energy to it, and something to provide optical feedback.

The gain medium is a material with properties that allow it to amplify light by stimulated emission.

Light of a specific wavelength that passes through the gain medium is amplified ( increases in power ).

For the gain medium to amplify light, it needs to be supplied with energy.

The most common type of laser uses feedback from an optical cavity — a pair of mirrors on either end of the gain medium.

Light bounces back and forth between the mirrors, passing through the gain medium and being amplified each time.

This glowing plasma is excited and then acts as the active laser medium | gain medium through which the internal beam passes, as it is reflected between the two mirrors.

The gain medium is excited by an external source of energy into an excited state.

The gain medium of a laser is normally a material of controlled purity, size, concentration, and shape, which amplifies the beam by the process of stimulated emission described above.

The gain medium absorbs pump energy, which raises some electrons into higher-energy (" excited ") quantum states.

In a few situations it is possible to obtain lasing with only a single pass of EM radiation through the gain medium, and this produces a laser beam without any need for a resonant or reflective cavity ( see for example nitrogen laser ).

The resonator typically consists of two mirrors between which a coherent beam of light travels in both directions, reflecting back on itself so that an average photon will pass through the gain medium repeatedly before it is emitted from the output aperture or lost to diffraction or absorption.

If the gain ( amplification ) in the medium is larger than the resonator losses, then the power of the recirculating light can rise exponentially.

But each stimulated emission event returns an atom from its excited state to the ground state, reducing the gain of the medium.

With increasing beam power the net gain ( gain minus loss ) reduces to unity and the gain medium is said to be saturated.

The gain medium will amplify any photons passing through it, regardless of direction ; but only the photons in a spatial mode supported by the resonator will pass more than once through the medium and receive substantial amplification.

For continuous wave operation it is required for the population inversion of the gain medium to be continually replenished by a steady pump source.

The lasing medium in some dye lasers and vibronic solid-state lasers produces optical gain over a wide bandwidth, making a laser possible which can thus generate pulses of light as short as a few femtoseconds ( 10 < sup >− 15 </ sup > s ).

In a Q-switched laser, the population inversion is allowed to build up by introducing loss inside the resonator which exceeds the gain of the medium ; this can also be described as a reduction of the quality factor or ' Q ' of the cavity.

In a continuous wave ( CW ) laser, the balance of pump power against gain saturation and cavity losses produces an equilibrium value of the laser power inside the cavity ; this equilibrium determines the operating point of the laser.

If the applied pump power is too small, the gain will never be sufficient to overcome the resonator losses, and laser light will not be produced.

Then, after the pump energy stored in the laser medium has approached the maximum possible level, the introduced loss mechanism ( often an electro-or acousto-optical element ) is rapidly removed ( or that occurs by itself in a passive device ), allowing lasing to begin which rapidly obtains the stored energy in the gain medium.

* A gain medium or laser medium, and

The gain medium is the major determining factor of the wavelength of operation, and other properties, of the laser.

There are hundreds if not thousands of different gain media in which laser operation has been achieved ( see list of laser types for a list of the most important ones ).

Neodymium ions in various types of ionic crystals, and also in glasses, act as a laser gain medium, typically emitting 1064 nm light from a particular atomic transition in the neodymium ion, after being " pumped " into excitation from an external sourceNeodymium doped glass slabs used in extremely powerful lasers for inertial confinement fusion.

If the number of photons being amplified per unit time is greater than the number of photons being absorbed, then the net result is a continuously increasing number of photons being produced ; the laser medium is said to have a gain of greater than unity.

Such a gain medium, along with an optical resonator, is at the heart of a laser or maser.

The special condition is known as a population inversion, a rather unusual condition that must be effected in the gain medium of a laser.

The kinetic of excitations in Yb-doped materials is simple and can be described within the concept of effective cross-sections ; for most Yb-doped laser materials ( as for many other optically pumped gain media ), the McCumber relation holds, although the application to the Yb-doped composite materials was under discussion .< ref name =" McCumberA ">< ref name =" McCumberB ">

In it, Rogers suggested that the client, by establishing a relationship with an understanding, accepting therapist, can resolve difficulties and gain the insight necessary to restructure their life.

None of these studies suggested any connection between percentage of calories from fat and risk of cancer, heart disease, or weight gain.

In order to gain approval from the Sporting Goods department, Quinn suggested Atari demonstrate the game to executives in Chicago.

Michael Tori, a professor at Marist College ( Poughkeepsie, New York ) suggested that Moon's conviction helped the Unification Church gain more acceptance in mainstream American society, since it showed that he was financially accountable to the government and the public.

Another suggested reform uniting all remaining five municipalities in the Berchtesgaden valley ( Bischofswiesen, Ramsau, Marktschellenberg and Schönau ) failed to gain enough popular support ; it passed in Berchtesgaden but failed everywhere else.

* Freud suggested that bad dreams let the brain learn to gain control over emotions resulting from distressing experiences.

Nestorius suggested the titleChristotokos ( Χριστοτόκος, " Christ-bearer "), but this proposal did not gain acceptance on either side.

" The owner came to me and suggested incorporation, and while I didn't think I had much to gain then, I agreed.

Chung labelled these criticisms " un-American " and " unpatriotic ", and suggested Navratilova should " go back to Czechoslovakia " rather than use her celebrity status to gain a platform for her complaints.

It is suggested that this is because when completing tasks that are highly accurate about a person's characteristics there is more to gain from succeeding in a task as it will therefore give more information about the person's characteristics than if it was low in accuracy.

It has been suggested that the next evolutionary step after knowledge economy is the network economy, where the relatively localized knowledge is now being shared among and across various networks for the benefit of the network members as a whole, to gain economic of scale in a wider, more open scale.

This composition, suggested by General Juan José Flores, was not set to music and did not gain popularity.

Since males have no role in parental care and give nothing to females except sperm, it is suggested that females gain genetic benefits from their mate choice, but this has not been established, in part, because of the difficulty of following offspring performance because males take seven years to reach sexual maturity.

He was so impressed with a briefing presented by the Israelis that he suggested a trip to Israel to the U. S. branch of Airports Council International in order to gain a deeper understanding of the methods employed by Israeli airport security and law enforcement.

Bull's ultimate goal was to fire a payload into space from a gun, and many have suggested that the ballistics study was offered simply to gain funding.

The Pan-Blue Coalition suggested that the shooting was not an assassination attempt but that it was staged to a self-inflicted wound in order to gain sympathy votes.

Cicero suggested that in order to gain respectability a merchant should buy land.

This was later evident in polls which suggested the ALP's primary vote was at around 40 per cent – the minimum considered necessary to gain government.

The birds ' bright colours are suggested to be an example of aposematism ( warning colouration ), and the similarity of the Hooded Pitohui and some forms of the Variable Pitohui might then be an example of Müllerian mimicry, in which dangerous species gain a mutual advantage by sharing colouration, so an encounter with either species trains a predator to avoid both.

It is suggested that the effect of NE is to control the gain of NMDA receptor-dependent homosynaptic LTD. Like norepinephrine, acetylcholine is proposed to control the gain of NMDA receptor-dependent homosynaptic LTD, but it is likely to be a promoter of additional LTD mechanisms as well.

Nevertheless, infanticide does occur in these groups, and is suggested that such practices serve to return a female to estrous and gain the opportunity to mate.

It has been suggested that this is one reason for the evolution of complex emotions in higher life forms, who, at least as infants, and usually thereafter, cannot survive without cooperating – although with maturation they gain much more choice about the kinds of cooperation they wish to have.

After King James published the Declaration of Indulgence in May 1687, Increase Mather sent a letter to the king, thanking him for the declaration, and then suggested to his peers that they also express gratitude to the king as a means to gain favor and influence.