Caf 2 reported significant improvements in average power of bulk oscillators with the generation of sub 70 fs with several watts 8. Kerr lens mode locking klm is a method of mode locking lasers via the nonlinear optical kerr effect. Cavitymode analysis of a kerrlens modelocked laser with a. Zns laser, generating 550 mw of 69 fs nearly transformlimited pulses at 2. Kerr lens mode locking has enabled the generation of the shortest pulses with durations down to. In general, modelocking establishes preference for pulsed operation, either in loss or. Cavity mode analysis of a kerr lens mode locked laser with a novel fivemirror cavity.
Intensity autocorrelation of a representative pulse width recorded at 607 nm from the kerr lens mode locked pr. In addition, sibbett and two research colleagues first demonstrated the kerr lens mode locking technique in a titaniumsapphire laser. Cavitymode analysis of a kerrlens modelocked laser with. Passive mode locking with an ideally fast saturable absorber semiconductor and dye lasers. The actual size for a pdf page is typically 100%, but the document may have been set to another magnification level when it was created. Mode locking thresholds as low as 156 mw are achieved. The general principle behind kerr lens mode locking is sketched in fig. Astigmatism in gaussianbeam selffocusing and in resonators for kerrlens mode locking. Ultrafast lasers modelocked by nanotubes and graphene. In addition, a general description is given to other mode locking techniques, which preceded kerr lens mode locking.
Kerr lens modelocking how is kerr lens modelocking abbreviated. The most common example of this is kerr lens modelocking of titaniumsaphhire ti. Kgw oscillator with an additional kerr medium pumped by a highbrightness fibercoupled diode laser. Kerrlens, modelocked lasers as transfer oscillators for. Us8798106b2 modelocking with reduced nonlinearity using. Energy scaling of kerrlens modelocked thindisk oscillators article pdf available in optics letters 3922 november 2014 with 190 reads how we measure reads. This is an important step, since kerr lens mode locked ti. Investigation of the kerrlens mode locking ability of cr.
Kerr lens mode locking is a technique for mode locking a laser, exploiting nonlinear selffocusing. By theoretical calculation of the group velocity dispersion in the laser gain, the compensation was employed for the realization of the continuouswave mode locked laser at the wavelength of 604 nm with the pulse width of 1. Modelocking of a cw laser university of new mexico. Such combined mechanism has the same effect as a saturable absorber. Passive mode locking using saturable absorbers an intracavity saturable absorber is able to fix phase of cavity modes variations slow saturable absorber fast saturable absorber kerr lens effect. Figure 1 shows a schematic of the experimental setup. However, kerr lens mode locking is not selfstarting 1,11. Kerr lens mode locking klm technique combined with highbrightness pumping. A laser cavity includes a gain medium for amplifying a light pulse in a light path, wherein the gain medium has a gain profile for amplifying the light pulse as a function of wavelength.
The optical kerr effect is a process which results from the nonlinear response of an optical medium to the electric field of an. Active mode locking with picosecond pulse duration was realized in 2000, semiconductor saturableabsorber mirror sesam mode locking was demonstrated in 2005, and kerr lens mode locking was achieved in 2009. Several types of cavity structures with which selfstarting operation of kerr lens mode locking lasers may be achieved are presented. Blue radiation emanating from the crystal has been identified as surface second harmonic and sum frequency generation. On the basis of this result the optimal cavity configuration for kerr lens mode locking is proposed that allows to achieve a sub100 fs pulse duration.
Analysis of laser cavities with selfstarting kerrlens. According to the present invention there is provided an injection modelocking tisapphire laser system that produces a unidirectional laser oscillation through the application of a ring cavity laser that incorporates no intracavity devices to achieve unidirectional oscillation. This method allows the generation of pulses of light with a duration as short as a few femtoseconds. It is developed with a view to modeling kerr lens mode locking, but promises much wider applicability.
Multipulse operation and limits of the kerr lens mode locking stability. Kerrlens modelocking klm is a method of mode locking lasers via the nonlinear optical kerr effect. A technique for mode locking a laser, exploiting nonlinear selffocusing. In this section, the mechanism of pulse formation is described in a qualitative and intuitive manner. Multipulse operation and limits of the kerrlens modelocking. On the contrary, kerr lens mode locking is known to support much shorter pulse durations 42, even beyond the emission bandwidthlimit of the laser gain medium 43, 44. Our group is doing research on new ways to mode lock lasers, specifically fiber lasers.
Pdf the abcdmatrix formalism is generalized for the description of self focusing and radially varying. To the best of our knowledge, this is the first demonstration of kerr. A meanfield model for kerr lens modelocking springerlink. Us6483858b1 injection modelocking tisapphire laser system. A pulse that builds up in a laser cavity containing a gain medium and a kerr medium experiences not only selfphase modulation but also self focussing, that is nonlinear lensing of the laser beam, due to the nonlinear refractive index of the kerr medium. Kerrlens mode locking is caused by the self focusing.
Analytic theories of additive pulse mode apm locking and kerr lens mode klm locking are developed. They provide a means for comparison of the two methods. Vier optics communications 115 1995 533538 i april 1995 optics communications kerr lens mode locking of a subpicosecond optical parametric oscillator r. Joachim herrmann, theory of kerr lens mode locking. An additive kerr medium is used for stable mode locked operation instead of semiconductor saturable absorber mirrors sesam, because kerr effect of the yb. The collidingpulse mode locked cpm laser a lens and a lens kerr lens mode locking kerr lensing is a type of saturable absorber. Kerrlens modelocking klm is a method of modelocking lasers via the nonlinear optical kerr. Pulses with durations as short as 14 fs and bandwidths of. The generation of 72fs hyperbolic secant pulses centered at 1050nm with 17. Multipulse operation and limits of the kerrlens modelocking stability vladimir l. Octavespanning lasers for optical metrology applications.
All structured data from the file and property namespaces is available under the creative commons cc0 license. Electrical engineering, technionisrael institute of tehcnologoy haifa 32000, israel 2research laborartoty of electronics, massachusetts institute of technology cambridge, ma 029 3 racah institute of physics, the hebrew university jerusalem 91904, israel. This has led to a number of mode locking techniques to obtain such pulses, for example acoustooptic, injection, synchronouspump, collidingpulse mode locking, and kerr lens mode locking. Kerrlens mode locking is caused by the selffocusing. Selfstarting of passive mode locking ariel gordon1,2, omri gat1,3, baruch fischer1 and franz x. All solidstate passively modelocked ultrafast lasers based. Ultrashort optical pulses are produced by mode locked lasers. The fundamental laser was captured by the intracavity raman cavity, and the mode beating of the fundamental laser and the. Directly diodepumped, kerrlens modelocked, fewcycle cr. Pulses as short as 85 fs at a central wavelength of 1074. Pdf the abcdmatrix formalism is generalized for the description of selffocusing and radially varying.
Cavity mode analysis of a kerrlens mode locked laser with a novel fivemirror cavity. Generation of 85 fs laser pulses from a diodepumped kerr. Realization of a kerrlens modelocked verticalexternalcavity. It is known that kerr lens mode locking technique based on the nonlinear refractive index n2 of the laser medium itself is a manner for femtosecond laser pulse generation. We have demonstrated a new method of mutual kerrlens modelocking which provides for a means to define the crossing point of counterpropagating waves in a ring or linear laser, without the use of a saturable absorber. Analytical design of symmetrical kerrlens modelocking laser cavities. Proceedings of spie the international society for optical engineering. Control and manipulation of the kerrlens modelocking. We introduce a novel concept for optical frequency measurement and division which employs a kerr lens, mode locked laser as a transfer oscillator whose noise properties do not enter the measurement process.
Kerr lens mode locking without nonlinear astigmatism. In singlecavity configurations, klm locking and apm locking produce comparable ratios of amplitude to phase modulation. On the contrary, kerr lens mode locking is known to support much shorter pulse durations 23, even beyond the emission. The article on passive mode locking explains how a saturable absorber leads to mode locking. Kerrlens modelocking 14 and semiconductor saturable absorber mirrors sesams 46 have changed the outlook of ultrafast lasers over the past two decades. Design issues for this modelocking technique are discussed. Femtosecond kerrlens modelocked thindisk oscillators constitute a peak and average power scalable oscillator concept. A multiwatt, multighz laser eyesafe laser was obtained by simultaneously qswitched kerr lens mode locking and stimulated raman scattering. Therefore, boosting up the peak power of femtosecond pulses in a kerr lens mode locked thindisk oscillator can accelerate the progress of application of thindisk oscillators in the scienti. We configured kerrlens modelocked lasers based on yb.
Using the latter two techniques, pulses of less than 100 fs duration can be readily obtained. Ultrashort laser pulses carlo antoncini department of physics university of reading whiteknights, reading, rg6 6af, uk abstract. Pdf energy scaling of kerrlens modelocked thindisk. Recent research has led to techniques such as kerr lens mode locking to enable pulse duration.
Compared with the active mode locking technique, passively mode locked laser with saturable absorber is able to generate much shorter pulse with a simple configuration. Energy scaling of kerr lens mode locked thindisk oscillators article pdf available in optics letters 3922 november 2014 with 190 reads how we measure reads. This effect is called selffocusing and has important implications for passive mode locking of lasers kerr lens mode locking and for optical damage of media catastrophic selffocusing. We have demonstrated a highpower kerr lens mode locked yb. This document provides supplementary information to directly diodepumped. Thindisk technology uniquely enables the simultaneous scaling of both average and peak powers, while maintaining an excellent beam profile. Laubereau physik department ell, technische universitdt munchen, 85748 garching. Kerr lens modelocking of a subpicosend optical parametric. Kerr lens mode locking without nonlinear astigmatism shai yefet, valery jouravsky, and avi peer department of physics and bina center of nanotechnology, barilan university, ramatgan 52900, israel. Yag lasers 2, but kerr lens mode locking is not performed for other ybdoped materials at this moment. A simple analytical formalism yields closedform expressions for the depth of passive amplitude modulation introduced by either the spatial gain profile or a hard aperture inserted in the resonator. Vier optics communications 115 1995 533538 i april 1995 optics communications kerr lens modelocking of a subpicosecond optical parametric oscillator r. Yag is an attractive material for highpower and ultrashort pulse laser because of its high quantum efficiency exceeding 90% and wide gain spectrum larger than about 10 nm.
Highpower simultaneously qswitched and kerrlens mode. Section 4 describes the fundamental concepts of kerr lens mode locking. This method is analogous to kerr lens mode locking. Femtosecond laser pulses in a kerr lens modelocked thin. The high power fundamental laser at 42 nm was generated efficiently with a sidepump nd. Download pdf 584 kb abstract the kerrlens mode locking stability and the ultrashort pulse characteristics are analyzed numerically for the crdoped znte, znse, zns active media. Sesam allowed mode locking to selfstart, the resultant pulse duration of 180 fs was significantly longer than allowed by the gain medium. The average output power was 80 mw under a 4w diode pump power. In addition the position of a hard or soft aperture similar as a fast saturable absorber in a klm laser is discussed. Znse active medium predicts the strong defocusing cascaded secondorder nonlinearity within 2000 3000 nm spectral range. Analysis of laser cavities with selfstarting kerrlens mode.
Learn how and when to remove this template message. Kerr lens and additive pulse mode locking soft aperture hard aperture gain. Rp photonics encyclopedia kerr lens mode locking, hard. Ultrashort laser pulses are considered to be those whose pulse duration is less than a few picoseconds 1012 s long. October 2019 learn how and when to remove this template message. Moreover, klm does not require a sophisticated design and manufacturing process.
Control and manipulation of the kerrlens modelocking dynamics in lasers shai yefet department of physics ph. Abstract this document describes how 445nm laser diodes were successfully used to pump a soft aperture kerr lens modelocked ti. The shortest pulses are produced by passive mode locking, typically based on an effective saturable absorber that utilizes the nearinstantaneous kerr effect. Directly diodepumped, kerrlens mode locked, fewcycle cr. The mechanism for selfstarting operation of kerr lens mode locking laser is studied. Saturable gain and loss the passively mode locked dye laser some common dyes and their corresponding saturable absorbers colliding pulses have a higher peak intensity. Sf57 glass is used to stabilize the mode locked oscillation to decrease the intracavity loss to increase the oscillation bandwidth for transform limited pulse generation. Ylf laser, initiated by means of a liquid saturable absorber. We propose a new meanfield or master equation capable of describing transverse effects, pulse evolution and nonlinearity in an appropriate cavity.
Analytic theory of additive pulse and kerr lens mode. Kerr lens mode locking klm is a technique of passive mode locking a laser, using an artificial saturable absorber based on kerr lensing in the gain medium. The general principle behind kerrlens mode locking is sketched in fig. For negative n 2, the nonlinearity is selfdefocusing. Ramanassisted broadband modelocked laser scientific reports. Passive mode locking can typically achieve pulses as short as a few picoseconds in broad bandwidth solidstate materials. We experimentally demonstrate that this method opens up the route to phaselink signals with arbitrary frequencies in the optical or microwave range while their frequency stability is. Thesis submitted to the senate of barilan university. Feb 01, 20 we report the softaperture kerrlens modelocked cr. Multipulse operation and limits of the kerrlens mode.
Selffocusing in conjunction with an intracavity aperture creates a powerdependent amplitude modulation in laser oscillators, which allows passive mode locking. It is suitable for generating fewfemtosecond laser pulses. The collidingpulse mode locked cpm laser a lens and a lens kerr lens mode locking kerr lensing is. First demonstration of harmonic modelocking in a selfmode. Pdf multipulse operation and limits of the kerrlens. Al 2o 3 laser achieved by use of an extended cavity design is demonstrated. Research in germany has produced the first demonstration of harmonic modelocking in a self. If you have a disability and are having trouble accessing information on this website or need materials in an alternate format, contact web. Files are available under licenses specified on their description page. We have demonstrated a new method of mutual kerr lens mode locking which provides for a means to define the crossing point of counterpropagating waves in a ring or linear laser, without the use of a saturable absorber. In a nutshell, kerr lens mode locking provides a means for producing femtosecond 1018 s laser pulses by conveniently exploiting a nonlinear optical effect in the laser crystal itself. To demonstrate graphene mode locking of the alexandrite laser, we adopt a resonator configuration similar to what was previously used for kerr lens mode locking experiments 20. Apr 24, 2001 the mechanism for selfstarting operation of kerr lens mode locking laser is studied. Abstract this document describes how 445nm laser diodes were successfully used to pump a soft aperture kerr lens mode locked ti.
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