An ultrashort pulse laser is a

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...

that emits ultrashort pulses of light, generally of the order of

femtosecond A femtosecond is a unit of time in the International System of Units (SI) equal to 10 or of a second; that is, one quadrillionth, or one millionth of one billionth, of a second. For context, a femtosecond is to a second as a second is to about 3 ...

s to one

picosecond A picosecond (abbreviated as ps) is a unit of time in the International System of Units (SI) equal to 10−12 or (one trillionth) of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000&nbs ...

. They are also known as ultrafast lasers owing to the speed at which pulses "turn on" and "off"—not to be confused with the speed at which light propagates, which is determined by the properties of the medium (and has an

upper limit In mathematics, the limit inferior and limit superior of a sequence can be thought of as limiting (that is, eventual and extreme) bounds on the sequence. They can be thought of in a similar fashion for a function (see limit of a function). For a ...

), particularly its

index of refraction In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...

, and can vary as a function of field intensity (i.e. self-phase modulation) and wavelength (

chromatic dispersion In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity t ...

). Common current ultrashort pulse laser technologies include Ti-sapphire lasers and dye lasers. High output peak power usually requires

chirped pulse amplification Chirped pulse amplification (CPA) is a technique for amplifying an ultrashort laser pulse up to the petawatt level, with the laser pulse being stretched out temporally and spectrally, then amplified, and then compressed again. The stretching and ...

of a seed pulse from a modelocked laser. Dealing with high optical powers also needs the

nonlinear optical Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in ''nonlinear media'', that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typica ...

phenomena to be taken in account.

Use in Pathogen Inactivation

Tsen and colleagues developed a SEPHODIS (selective photonic disinfection) technology using an ultrashort pulse laser to kill viruses including

HIV The human immunodeficiency viruses (HIV) are two species of '' Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immu ...

, influenza virus, and

norovirus Norovirus, sometimes referred to as the winter vomiting disease, is the most common cause of gastroenteritis. Infection is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may also occur. Symptoms usually deve ...

es. The technique appears to damage viral capsids while preserving other proteins and biological materials, although these claims have been disputed elsewhere. The ultrashort pulse laser treatment may have potential applications in the disinfection of medicines, in the production of inactivated vaccines, and in the possible future treatment of blood-borne viral infections from agents such as

and

Ebola virus ''Zaire ebolavirus'', more commonly known as Ebola virus (; EBOV), is one of six known species within the genus '' Ebolavirus''. Four of the six known ebolaviruses, including EBOV, cause a severe and often fatal hemorrhagic fever in humans and o ...

References

External links

* Ultrafast Lasers
An animated guide to the functioning of Ti:Sapphire lasers and amplifiers.
* Laser types {{Technology-stub

Use in Pathogen Inactivation

See also

References

External links