Transforming the Idler to Seed Raman Amplification

Transcription

1 Transforming the to Seed Raman Amlification S. BUCHT, D. HABERBERGER, J. BROMAGE, and D. H. FROULA University of Rochester, Laboratory for Laser Energetics Motivation Motivation Raman amlification transfers energy from a long-ulse um laser to a short-ulse seed laser at the resonance condition An efficient amlifier requires large electron lasma waves and a long seed ulse Efficiency is caed for seed ulses longer than the Raman growth rate The analytic solution to the couled-wave equations for um deletion is an attractor solution with the form ~um = ~seed ~lasma ~um = ~seed ~lasma efficiency? Dn e L seed? um: 153 nm (Nd:glass) I seed Tseed EPW: electron lasma wave The creation of an energetic and resonant seed is challenged by the availablity of high-ower lasers at the resonance condition An energetic seed at the resonance condition can be obtained from the idler of an OPCPA system Number of lasers E2521b E OPAL idler s 1 s NOPA**2 NOPA3 1.5 ns 1.5 ns NOPA4a NOPA4b UFE* Dazzler 1.5-ns/2-nm The idler from an OPCPA system at LLE (OPAL) sans the region set by the resonance condition and a 153-nm um laser OPCPA: otical arametric chired-ulse amlification OPAL: otical arametric amlifier * C. Danson et al., High Power Laser Science and Engineering 3, e3 (215). E nm to 123 nm Eidler: 2 mj 13 Wavelength (nm) The idler is an existing byroduct of all OPCPA systems, but has two roblems reventing its use as a high-fidelity laser Immediate entrance into the um deletion regime requires an energetic seed. E26235 Prism lane Angular disersion comensator 1.5-ns/8-nm comressor 2 mj 1 fs 117 nm Esig: 25 mj 81 nm to 11 nm *UFE: ultra-broadband front end **NOPA: noncollinear otical arametric amlifier E252b An image-relay system brings the wavelengths into satial alignment and reduces the angular disersion A grism uses gratingrism elements to rovide negative second- and third-order hase The comlex hase reversal of the idler requires a with negative second-and third-order hase to use with a grating comressor Otical arametric amlification is a three-wave mixing rocess inside a nonlinear um: narrowband, transfers energy to the signal and idler ks k ki Comlex sectral hase and angular disersion make the idler a challenge to use as a high-fidelity laser. E2523c Standard signal: broadband, gains energy from the um idler: has equal energy and normalized bandwidth as the signal Normal oeration oeration Alternate idler oeration for OPCPA system: Conservation of energy and momentum roduces an idler with Grism comlicated hase relationshi to the signal angular disersion E2524a Stretcher Grating comressor Normal OPCPA system: Amlified idler/ signal Comressor {(3)(~) {(2)(~) {(3)(~) Proerty of grating comressor Requirement for a transformlimited ulse Grating comressor OPA changes second order Stretcher not third accounts for but order hase most of the of the idler signal hase 2 {^s h. { i^2h {^s3h. { i^3h Grism 2 Comressed ulse {(2)(~) Exlanation A rism air with angular disersion that is equal and oosite of the idler collimates light without adding ulsefront tilt E26238 The otical arametric amlifier (OPA) changes the chir (secondorder sectral hase) but not third-order sectral hase of the idler Proagation time ( 14 ~t).4 lane 1.5-ns/5-nm Nd:glass Ti:sahire OPCPA OPAL.2 Angular disersion is removed by imaging the idler onto a disersive element >5-TW laser facilities 15.1 aseed EPW Bragg grating Tseed c E , Seed the electron lasma wave amlitude is roortional to the seed electric field lasma: ne = 119 cm3 Seed: 111 to 123 nm (OPCPA) TR n le De Time angular disersion comensator ted This can be understood by modeling the lasma wave as a volume Bragg grating.6 io grism m u -deletion solution et m s Pla The highest transfer of energy occurs when the resonance condition is met: ~ um ~ lasma - 5 l e av w a a seed Tseed de ed Se d fie i l Am robe.8 Two unique subsystems are needed to transform the idler for use in a Raman amlification exeriment m Pu 1, m Pu A system is roosed for roviding a Raman amlifier seed ulse using an otical arametric chired-ulseamlification (OPCPA) system OPAL (otical arametric amlifier line) A Raman amlifier has the otential to byass current limits on eak laser intensity Proosed seed Efficiency An efficient Raman amlifier requires an energetic seed that matches the resonance condition Motivation ~Tseed Summary A grism is a grating mounted next to or etched onto a rism Angular disersion from bulk material allows for negative third order hase {3 { 2 81 n sin ^i diffh sin ^i inhb The design achieves a 2-fs FWHM* with a standard grating comressor Grism 1 E26237 Roof mirror * FWHM: full width at half maximum

2 Summary An efficient Raman amlifier requires an energetic seed that matches the resonance condition A system is roosed for roviding a Raman amlifier seed ulse using an otical arametric chired-ulseamlification (OPCPA) system OPAL (otical arametric amlifier line) Two unique subsystems are needed to transform the idler for use in a Raman amlification exeriment grism ~ um = ~ seed ~ lasma angular disersion comensator E26233

3 Motivation Raman amlification transfers energy from a long-ulse um laser to a short-ulse seed laser at the resonance condition m Pu ed Se ed lifi Am robe e av w a sm Pla Time m De e let u d A Raman amlifier has the otential to byass current limits on eak laser intensity The highest transfer of energy occurs when the resonance condition is met: ~um = ~seed ~lasma um: 153 nm (Nd:glass) lasma: ne = 119 cm3 Seed: 111 to 123 nm (OPCPA) E2521b

4 Motivation An efficient amlifier requires large electron lasma waves and a long seed ulse The analytic solution to the couled-wave equations for um deletion is an attractor solution with the form aseed Tseed ~ um ~ lasma - 5 This can be understood by modeling the lasma wave as a volume Bragg grating -deletion solution efficiency? D n L? I T e seed seed seed the electron lasma wave amlitude is roortional to the seed electric field Seed EPW Bragg grating T seed c E26234 EPW: electron lasma wave

5 Motivation Efficiency is caed for seed ulses longer than the Raman growth rate 1, Proosed seed.8 deletion.6 ~T seed T R 1, Efficiency a seed Proagation time ( 1 4 ~t) Immediate entrance into the um deletion regime requires an energetic seed. E26235

6 The creation of an energetic and resonant seed is challenged by the availablity of high-ower lasers at the resonance condition Number of lasers >5-TW laser facilities OPAL idler Wavelength (nm) Nd:glass Ti:sahire OPCPA OPAL The idler from an OPCPA system at LLE (OPAL) sans the region set by the resonance condition and a 153-nm um laser E26236 OPCPA: otical arametric chired-ulse amlification OPAL: otical arametric amlifier * C. Danson et al., High Power Laser Science and Engineering 3, e3 (215).

7 An energetic seed at the resonance condition can be obtained from the idler of an OPCPA system 1.5-ns/5-nm 1 s 1 s 1.5 ns 1.5 ns 111 nm to 123 nm E idler : 2 mj Angular disersion comensator 1.5-ns/8-nm comressor UFE* Dazzler NOPA**2 NOPA3 1.5-ns/2-nm NOPA4a NOPA4b E sig : 25 mj 81 nm to 11 nm 2 mj 1 fs 117 nm E252b *UFE: ultra-broadband front end **NOPA: noncollinear otical arametric amlifier

8 The comlex hase reversal of the idler requires a with negative second-and third-order hase to use with a grating comressor The otical arametric amlifier (OPA) changes the chir (secondorder sectral hase) but not third-order sectral hase of the idler E2524a Normal OPCPA system: Standard Grism Alternate idler oeration for OPCPA system: Grating comressor Grating comressor Normal oeration oeration Exlanation Stretcher Amlified idler/ signal Comressor Comressed ulse { (2) (~) { (3) (~) { (2) (~) { (3) (~) Stretcher accounts for most of the signal hase OPA changes second order but not third order hase of the idler 2 { ^ h. { ^2h s i 3 { ^ h. { ^3h s i Proerty of grating comressor Requirement for a transformlimited ulse

9 The idler is an existing byroduct of all OPCPA systems, but has two roblems reventing its use as a high-fidelity laser k s k Comlex sectral hase and angular disersion make the idler a challenge to use as a high-fidelity laser. k i Otical arametric amlification is a three-wave mixing rocess inside a nonlinear um: narrowband, transfers energy to the signal and idler signal: broadband, gains energy from the um idler: has equal energy and normalized bandwidth as the signal Conservation of energy and momentum roduces an idler with comlicated hase relationshi to the signal angular disersion E2523c

10 A grism uses gratingrism elements to rovide negative second- and third-order hase Grism 2 A grism is a grating mounted next to or etched onto a rism Angular disersion from bulk material allows for negative third order hase { { n sin^idiffhsin^iin 8 hb The design achieves a 2-fs FWHM* with a standard grating comressor Grism 1 Roof mirror E26237 * FWHM: full width at half maximum

11 Angular disersion is removed by imaging the idler onto a disersive element lane Prism lane An image-relay system brings the wavelengths into satial alignment and reduces the angular disersion A rism air with angular disersion that is equal and oosite of the idler collimates light without adding ulsefront tilt E26238