EUV_FEL ðp¢½ÅÌ¨¿Ìñü`õw»ÛÌ¤ÄcmIv|dCÊMåw[U[V¢ã¤Z^[§182_8585 s²zs²zu 1_5_1É[OõÌæÅÌ©Rdq[U[Ì­UÍC±êÜÅ¢ïÅÁ½Zg·ÌæÅñü`õwÌÂ\«ðå«­L°é±ÆÉÈÁ½B±±ÅÍCÁÉÅÌðúóÔÆµÄ¶¬³ê½GlM[óÔÅÂ\ÆÈÁ½Vµ¢ñü`õw¤ÉÂ¢ÄÐî·éB1. Í¶ßÉÄÝæ¤B´q§x ni mcm|3 nCCI»GlM[ hnmeVnCzûW amcm|1nCpX tmsnCfd× e Æ´IÉzûªÈ¢}¿Å­UÅ«é©Rdq[U[·êÎC»Ì­xÍ Itni e hn/a ÆÈéB ±Ì®ð©éÍCÊíÌõw[U[è@Å­¶µÉ­¢É[OCXÆCa Ìå«ÈàÌªLÉÈéªÉ[OæÅÍzûWüÌæÅàg·ÂÏC´ZpX«ð¿C­xÌõðªeÕÉ105`106 cm|1 ÉÈèC¼Ìg·Éä×Kv­­¶Å«éB±êÉæèC±êÜÅÜèJñ³êÄ¢ÈxÍ¬³­ÈÁÄ¢éBàµCüËõÌGlM[ð»Ý©Á½É[Og·ÈºÅÌñü`õw¤ªå«­WJÌ SCSS ±Á¬íÅÌl hn25 eV Æ·êÎCIt0.2Å«éæ¤ÉÈÁÄ«½B±Ìg·ÌæÅCRq[`2mJ/cm2nÅÀ»Å«é±Æªí©éB±êÍC10 mJgÈõ©çÔÉóÔRq[Xð§äµ½[U[õÌõð10 mm öxÉWõ·êÎ\ªB¬Å«élÅ

ÉÈÁ½±ÆÍC±êÜÅÔOÉÂÉOõÅsíêÄ»ÝÌõ¹CõwnÅeÕÉBÅ«éxÉèCéBê«½ñü`õwÌ­Wðl¦êÎC³çÉ½lÈpð¶ûCGlM[óÔÉÈÁ½¨¿ÍC»ÌãClXÈÉ

Ýo¹é±ÆðÓ¡µÄ¢éBÁÉà®Ì`±ÑÌvYaßöðÊßµÈªçc£CòU·é±ÆÉÈéB±Ì}ügÅÜég·ÈºÌõÅÍC±êÜÅÂÉÔOÌ¬xÍCãNµ½dqð`±ÑàÉÛÅ«êÎCMIÅÍÎÛÆÈèÉ­©Á½à®ÅÈvfÉÈé½ßC¨æ»¹¬1000 m/sCÅÌÌ´qÔÁÄàCUdÌÆ¯lÉlXÈ¤ÂðÂ}ÌÆµÄgp·é±ÆªÂ\ÉÈéB£ðl¦C±Ì£Ú®·é½ßÌÔÍ¨æ»250 fs

êÊÉC±Ìg·ÌæÅÍCÅOkdqÌªÉ©çCàÆÈéB±ÌÔàÉGlM[ðüÍÅ«êÎC§xkdqÌãNÉCI»ÈÇª¤ÂGlM[ÌÎÛÆÈóÔðÛÁ½ÜÜÙÆñÇÌ\¬´qðõCI»ÉãNéBi±±Åæèµ¤¨¿óÔÍ½tóÔÉÅ«é±ÆÉÈéBéàÌÅÍ

È¢½ßCàkÌdqªãNCCI»³ê½êÉC¢±Ìæ¤ÈóµÌCäXÍC±ÌàvãNÉCI»íäé`±ÑÉ¶Ý·éÌ©C©RdqóÔÈÌ©CÍ½ªN«Ä¢éÉàÖíç¸CÅÌÌ§xC´qzuðÛ

Ü½»ÌóÔÔðs«µÄ¢éÌ©æÊÅ«È¢óÔà¿C·¢£ÅÌ«ðÛ½¹é±ÆªÂ\ÅæèµÁÄ¢éB»Ì½ßCÈºÅÍàkdqÌãNÉC

½­ÌVµ¢pª­WÅ«éÆl¦Ä¢éB±Ì¨¿óêÎCI»Æ¢¤¾tðgpµÄ¢éBj»êÜÅCõw[Ôðá·ÅÈ¨©ÂàvãNóÔÉU[ªÎÛÆµÄ«½g·ÍÍÅÍCà®Ìõwª¢µ Ä ¢ é Æ ¢ ¤ Ó ¡ Å coldíäé`±ÑÌdqÉæé©RdqIÈ«¿ªåÆÈÁÄ(CHAS)1_3) Æ¼t¯C±Ì¨¿óÔð²×é¤Cp¢½ªC»ÌvY}ügð´¦éZg·ÉÈéÆCÕÈÇð©±ñ¾¤ðsÁÄ¢éBE§xÈºÆÈè¨¿àÉNüÅ«éæ¤ÉÈéB±ÌêÌÝìpßöÍCà®ÅÌ`±Ñª\¬´qÌÅOké´qªÅÌð\¬

Hollow±Ì CHAS ¶¬Éæè½ªÏíé©GAtomSolidPÉl¦êÎC´qð\¬·éàvdqª 1 Â²¯é½ßCcèÌdqðp¢ÄìçêÄ¢é±Æðl¦éÆCàkdqÌõdqÍæè­­´qjÉø«ñ¹çêC»ÌÊCGlãNCCI»ªåÆÈÁÄ­éBà¿ëñCVNgM[ÊÍGlM[¤ÉVtg·éBàµCÆËÔúËðnßÆµÄC±ÌÌæÌõÍ±êÜÅà¶Ýµª\ªZÔÅC·£«ªÛ½êéÆ·éÆCÆËÄ¢éBÉ[O©Rdq[U[Ìo»Éæè½ªÏíOãÅCñÜðð½·g·ªÙÈé¨¿É¬ÉÏ»Á½©G·é±Æªl¦çêéB±ÌÏ»ÍC±Ìg·ÌæÅ\®

»êÍCtFgbÖÌ´ZpX»ÆÔÉéBá¦ÎC­x«ÌõwfqJ­ÖÆpÅ«é®ÆÈéBFig. 1 É»ÌTOÚÀÆµÄÅÌÌSÄÌ´qðCI»Å«é­xðl¦}ð¦µÄ¢éB±±ÅCüËõÉæèàvãNÉCIóÔÅÌWõÉæé­x»É

úËõ Sept. 2010 Vol.23 No.5  317(C) 2010 The Japanese Society for Synchrotron Radiation ResearchFig. 1

Change of energy state in ordered Cold Hollow Atom Solid(CHAS). After photo­excitation of an inner shell electron toconduction band in metal, the energy state will be shiftedhigher. Keeping excited electron in the conduction ban andkeeping charge balance of material neutral will result in slow­
ing expansion of CHAS. The energy shift of resonant ab­sorption edge will be used for switching device for highenergy photons.

»³êC¤ÂGlM[ªVtg·é±ÆÅCæèàÖ
NüªN«Äs­±ÆªúÒÅ«éBãqÌ\®fqðæP àvãN³ê½dqª`±ÑÈèÀ»³¹é½ßÉÍCò
Q ãNÊzû
ÇÉæèÜêCd×«ªöêÈ¢CòiãNÊ©ç³çÉõqðzûµÄãÌÊÖãN³ê

Fig. 2 Transmitted spectrum of Sn (thickness: 50 and 80 nm).
Sharp absorption edge at about 50 nm is shown in this pic­
ture. We expect the edge wavelength will shift toward shorter
wavelength and the transmittance will increase after enoughexcitation of electron at this shell.

é»ÛjÆ¢Á½îêóÔÈO©çÌzûª­È¢óÔÅé±ÆCªKvÉÈÁÄ­éB±êÜÅCKitamura1)Ì
vZÈÇÉæèCàµCCI»µ½dqðà®ÌtF~Ê¼ãÉãN³¹é±ÆªÅ«êÎCLi ÈÇÌNX^ÅCd×aªöê¸CÈ¨©ÂCãN´q¯mÅÀèÈNX^ðÛÅ«é±Æª_IÉ¦³êÄ¢éB±
Ì½ßÉà¸xÌ¢g·`[jOªKvÆÈéªCEUV ©Rdq[U[Í»êàÂ\ÉµÄ¢éB

2. ´ZpX EUV [U[ÆËOqÌÚIÌ½ßÉCSCSS ±Á¬í©çÌ´Zp
X EUV [U[Éæè´ÀØÀ±ðsÁÄ¢éB±Ì[U[ÅÍCõqGlM[ª20`25 eV ÅÁ½½ßC±ÌÌæÅCV[vÈzûGbWðÂ Sn ð^[QbgÆµÄIðµ½BFig. 2 ÉÆËOÌÅÌóÔÅÌzûXyNgð¶£æè¦µÄéB±ÌêCN kÌdqð`±ÑÖCI»³¹é±ÆÉÈéBÀ±ÅÍCú³30, 50, 80 nm Ì Sn ÌÆË EUV [U[Ì§ß¦ðªèµC»Ì¤ÂGlM[ªuÉÏ»·émØð¾Fig. 3

Experimental result of transmittance of Sn of 50 nm thick­ness. We observed large change of transmittance with intense
EUV illumination. We expect this phenomena for saturable
absorber in this wavelength.

éÚIÅÀ±ðsÁ½2) BFig. 3 É»ÌÊÌêáð¦µÄ¢éªCüË[U[­xðã°Äs­Éµ½ª¢C­OãÅå«È§ß¦·ð¶Þ½ßÉÍCFig. 1 É¦³êÄ¢ÂOazûßöð¦·±Æªª©Á½B±Ì»ÛÌµ«¢lÍCOqÌÈPÈ©ÏàèÆ¯È¢éæ¤Èzû[ªÚ®·é±ÆªÅàà¾µâ·¢BÜlÆ È ÁÄ ¢ éB À ±f [ ^ Æó Ô 1  ³C ã  ÊÉ

½C±Ìå«È§ß¦ÁÍCOazûÌæÆ»êÈOÅaCãNãÊzûÜÅl¶µ½V~

[VfõÌ¸Wªå«­Ï»·éÌÅC¨¿àÅõª Fig. 4ÆÌärÍCúÌzûWð 2`3~106 cm|1 Åæ­êÌæ¤ÉV[vÈtgðÛ¿ÈªçNüµÄ¢­±v·é±Æªª©Á½BP zûOaÌOãÅ 2³ÄC±ÌÀ±ÊÅÍCòÆªª©éB±ÌtgªØè½Á½\¢ÍCzûOaÌªN«é¡OÜÅá¢§ß¦ðÛÂ±ÆªÂ\ÅèCzû¦äªQ Åà¢§ß¦ÍC±Ìf[^ÍÍÅéCò

I[vÉv·éÔÍC±ÌtgÌúÝðu[`

à30÷öxé±ÆCÆ¢¤Á¥ªÝçêéB zûOaO¬x vhI/ni i±±Å h ÍÊqø¦jÅÁ½lÆ

318  úËõ Sept. 2010 Vol.23 No.5

EUV SASE_FEL pÌWJ ¡ EUV_FEL ðp¢½ÅÌ¨¿Ìñü`õw»ÛÌ¤§xÆ»ÌãNGlM[ðl¦éÆÉ½èOÅ
é±Æªí©éB¡C6~1022 cm|3 öxÌ´qÌ10÷ðàkãNÉCI»³¹æ¤Æµ½êC»ÌãNGlM[ª25 eV öxÌÅàO¤ÌàkdqãNÅàCàGlM[§xÍ2.4~104 J/cm3 C³Í·ZÅ0.24 Mbar ÉÈéBµ½ªÁÄnÌM»ãÌAu[VÍð¯çêÈ¢í¯ÅéB»êÅàC±Ìg·ÌæÅ\®õwfqªÅ«ébgÍ\ªÉéÆvíêÄ¢éBOqÌ 3fs ÌXCb`ÔªÀ»Å«Ä¢êÎC±Ìfq§ßãÌõðgÁÄVXeÌ·é[U[õÌpXæèÍé©ÉZ¢»ÛÌv[uÏªC10 nm ÅÌÂOazûÌÅ

é½ßÉC¾}¿ÆgÝí¹ÄVµ¢[U[`ÔiQ XCb`^jÈÇðÀ»Å«éÂ\«ªoÄ«Ä¢éB
³ÄCÂOazû»ÛÍCnÌÉaõ½àÉÏZ³ê½Fig. 4

Calculated results of penetration of EUV laser in Sn absorp­tion layer. The four level model is used for this calculation.
At earlier time, normal exponential penetration prole isshown. (T5) After starting saturable absorption, proles ofrelatively at intensity distribution with front of sharp inten­
sity drop are appeared. This intensity prole of bleaching
results in very fast opening speed when we apply this to real
optical devices.

ãNóÔÌä¦ðÇÌöxßçêé©CÅÜé»ÛÅ
é½ßÉC½õqâ½iKãNÈÇÌñü`õwßöÆÍÙÈéB©ÈÖvªÈÇÌ½ßÉÍãÒÌñü`ßöàpÅ«½ûª¤ÆµÄ­Wµ¤éB½¾µC½õqzûßöÅÍC2 õqzûÅÌÂ`ÔOæÅÌÀ±XP[OªèC2 õqzûWÍ EUV ÌæÅÉ[Éá¢lÉÈéÆ\z³êÄ¢éB±ÌÀ±XP[OÍ»ÌohMbvGlM[ Ebg Æ 2 õqzûW bÈé½ßC­xÆËðÉÍñíÉ¬XCb`ÆÈéª½äá·éÆ¢¤àÌÅC¨¨æ» 2 õqzûWÍC±Æªª©éBSCSS ±Á¬íÅÌÀ±ðÅÍC±Ìbmcm/W]8~10|12/EbgmeVnÆÈéÆµÄ¢éB±I[vÔÍ 3 fs ÆÈÁÄ¨èC\ª£ÍIÈ\®f

êð25 eV Ì 2 {Ì¤ÂGlM[ðÂnÅvZ·êÎCoCXªC±Ìg·æÅÅ«é±Æð¦µÄ¢é4)Bb6~10|13 cm/W ÆÈèC±Ìg·ÌæÅÌêÊIÈ§ß¨¿Ìü`zûúÝi1 mmjðl¦êÎCKvÆË

3. ³çÉáÁ½ñü`õwøÊÖ­xÍ1017 W/cm2 ÉÈÁÄµÜ¤Bà¿ëñCàkãNÉCI»ßöªÅÌÌªÉÆÍáÁ½¨ßöð 2 õÂOazûÍCîêóÔÌ´qÌå½ðãNÅ«CãqzûßöÅ·é±ÆÍ\ªl¦çêéªC\zÌãÅÍNÊzûª³Å«éêÉÍK¸N«éÆúÒÅ«é¢ïÅ»ÛÅ

é 2 iKãNzûßöÌêÍCæèá¢ÆË­xÅÀéBµ©µC±ÌW°ÆÈÁÄ¢éÌÍCîêóéÆvíêÄ¢éBêûC½ç©ÌÊðp·ÔÌ´qðÙÆñÇãN·éÉÍC¢­xÌõªKv»Â\ÅÅC»ÌÆËÉæèÁMªN«C¨¿»ÌàÌªÏ»µÄÆàÉ¤ÂóÔÉµÜ¤±ÆÅf[^x[XàÅÍÈ©È©©Â¯É­¢BéB±êÉÍCzûWÌå«È¨ÆgéªCàkãNÊª¤Ü­C1 õqC2 õq
éàÌÍ±êÜÅ¾íêÄ«Ä¢ép·é[U[Ìg·Æ¤ÂÊÌ®«ªKvÉÈÁÄ

±Ìæ¤ÈÅC»Ý_»wâèððÅ«éÏw^[«Ä¢éBÊíCÂ`ßÔOõÅÌÂOazûÍC»Ì

Qb gÉæè C½­Ìà ®Ì§ßÁ« ð²×é¤ ª

JèÔµgpðÂ\É·é½ßÉC­È­ÆàVOVSCSS ±Á¬íÅsíêÄ¢éB±êÜÅCAl, Ge, Sc,

bgx[XÅÍõwjóµ«¢lð±¦È¢àÌðgpTi, Sn, Au, SiO2 ÈÇªÆË­x 1~1012`1~1014 W/·é±ÆªêÊÅéBµ©µCEUV`X üÌÌæÅC

cm2Cg·51, 55, 61 nm ÅL­²×çêÄ¢é4)B½­ÌàkdqÌCI»ðÆàÈ¤êC¢­çtF~Ê¼¨¿ÅÍCü`zûÌ»ÛªÏª³êÄ¢éªCTi É¨ãÉdqðãNµCgÃ©ÈhóÔðìÁ½Æ±ëÅCà¢Ä 2 õqàµ­Í 2 iK 2 õqzûÌUé¢ð·ékÉó¢½ðßé½ßÉC»ÌãCI[WFdqú±ÆªÏª³êéæ¤ÉÈÁ½BoCÁ« X üúoªN±èC»êçÌßöÅ¶¶édqÍCtF~ÊÌy©ãÌ©RdqóÔÉsÁÄµÜ¤½ßCN[oXÌ@CdqÕËCÄßöÉæ

4. ³çÉGlM[§xCGlM[õqÖü©ÁÄ

éÁMªN«CÆË¨¿ÍAu[VðÆàÈ¤jóÌ½ßÉCòU·é±ÆÉÈéB±êÍCãN·×«´qSn â Ti ÈÇÌ EUV Ì æÅÌñü`õwøÊÌ­©

úËõ Sept. 2010 Vol.23 No.5  319

ÍCàkãN³ê½ÅÌóÔÌ¨«ªCéöxC½àÅÍ«ð¿ÂÂ¶ÝÅ«Ä¢é±Æðéõf[^àå«ÈsmÀ«ðÜñÅ¢éB»ÌÓ¡ÅL­¨éöx¿ð²×C»êðö\µÄ¢­±ÆàdvÈ¤ÉÈéÅÀØµÄ¢é±ÆÉÈéB»ÝÍ SCSS ±Á¬íª^ë¤B]Â\È20`25 eV ÉÀçêÄ¢éªC40 eV öxÜÅGQl¶£lM[ªãªêÎÙÆñÇÌà®ÌàkãNÉCI»óÔÌ¤ÂøÊð²×é±ÆªÂ\ÉÈéB{©Rdq
[U[Íg·ÂÏªå«ÈÁ¥ÅéÌÅC«±Ìæ¤È¤É­WµÄ¢­±ÆÉÈéÅë¤BÁÉC\¢ÌPÈ´qÙÇzû[Ì\¢ÍV[vÅèCÆËO1)2)ãÅÉ[OæÅÌõwÁ«Éå«ÈÏ»ð¶Ýo·±ÆªúÒÅ«éBÁÉAJà®ÍC±ÌÓ¡ÅÈé^[QbgÆÈéÅ3)ë¤BêûCPÈ\¢Æ¢¤Ó¡ÅÍ K kÌdqÌàkã4)

Nà^[QbgÉÈè¤éB±êÍ·ÅÉ X üÌÌæÉüÁÄ­éªC·®Éé X ü©Rdq[U[Ì¤^[QbgÆµÄC·ÅÉÚWÝèªÈ³êÄ¢éiKÉ5)H. Kitamura: ``Cluster­model study on the K­shell excitedstates of crystalline lithium under intense laser irradiation'',Eur. Phys. J. D 52, pp. 147_150 (2009).
Hitoki Yoneda, et al.: Ultra­fast switching of light by absorp­
tion saturation in vacuum ultra­violet region, Optics Express,
vol. 17 Issue 26, pp. 23443_23448 (2009).
H. Yoneda, et al.: Observation of saturable absorption of Sn
metal lm with intense EUV laser pulse, Proc. of SPIE vol.
7501 (SPIE, Bellingham, WA 2009) pp. 33_43.
Y. Inubushi, et. al.: Measurement of saturable absorption byintense VUV free electron laser using uorescent material,Rev. Sci. Instrum. 81, 036101 (2010).
ÄcmIF­x X üªJñ·é¨CRev. Laser Eng.,
Vol. 37, No. 12, p. 893_
900 (2009).

ÈéBàµC±êªÂ\ÉÈéÆ keV ÌæÌõÉÎµÄà\®IÈõwfqðõ³¹é±ÆªÂ\ÉÈèCVµ¢ X üõwÌ­WÉÂÈªé©àµêÈ¢BÁÉ»óÉé¨¿ÅÍubO½ËÌpxªàkãNÉCI»ÉÆàÈ¤GlM[ÊÌuÌÄ\¬ÉæèÏ»·é±ÆªÂ\ÅC»ÌÓ¡Å EUV [U[ÆÌÝìpæèªèµâ·¢»ÛÉÈÁÄ­éÂ\«àéBOqµ½æ¤Èµ«¢l­xÍC1017 W/cm2 ÈãÉÈèC¡ãÌkeV Ìæ[U[­UÆ nm ­û©õwnªgÝí³ê
é±ÆÉæèC\ªÀ»Å«éÌæÆÈÁÄ¢é5)B

5. ÜÆßÅßCVµ­©Â©Á½ EUV ÌæÌÅÌðúóÔÆµ½ñü`õw»ÛÉÂ¢ÄCÐîðsÁ½B±êçÍCX ü©Rdq[U[p¤ÖÌ­WªìÉ¢ê½¤ÆÈÁÄ¨èCGlM[õqÌ½ßÌ\®Iõw
foCXJ ­Ì½ßÌ î{ÆÈé Ævíêé B½¾C

 ÒÐî ÄcmIdCÊMåw[U[V¢ã¤Z
^[É³ö
E­mail: yonedails.uec.ac.jpêåF[U[Èwmªðn1988NHÆåwHw¤ÈGlM[ÈwêUmÛöC¹CHwmBdCÊMåwV`[U[¤Z^[èC[U[ÉÀZp¤Z^[³öðoÄ2006Næè»EBå^GLV}[U[J­CoÍ THz
õ¹J­CX üÎõªõCÅÌ_vY}JÚóÔÌÈwCvY}tHgjNXÈÇÌ[U[ðx[XÆµ½îÕÈw C  p ¤  ð s ¢ C EUV _FEL CXFEL ÈÇÌVµ¢[U[ðp¢½Ýìp¤àX^[g³¹Ä¢éB

EUV ÌæÍC_»wÈÇÌe¿ªå«­CÜ½CQÆ

Nonlinear optics in high density matter withextreme ultra­violet free electron lasers
Hitoki YONEDA

Institute for Laser Science, University of Electro­Communications
1_5_1 Chofugaoka, Chofu­shi, Tokyo 182_8585

Abstract Intense pulses from extreme ultra­violet free electron lasers now open new possibilities of non­linear optics in many solid materials. We discuss nonlinear optical phenomena with high energy density condi­tion in condensed matter. We also introduce recent experimental data related to nonlinear optical phenomena
in EUV region which are recently observed in EUV laser experiments.

320  úËõ Sept. 2010 Vol.23 No.5