Esimemezelweni esiyingqopha-mlando ngobusuku bangomhla zi-3 kuMfumfu wezi-2023, kwethulwa uMklomelo KaNobel ku-Physics wonyaka wezi-2023, kuqashelwa amagalelo avelele ososayensi abathathu abadlale indima ebalulekile njengamavulandlela emkhakheni wobuchwepheshe be-laser be-attosecond.

Igama elithi "attosecond laser" lisuselwa kusilinganiso sesikhathi esifushane ngendlela emangalisayo esebenza kuso, ikakhulukazi ngokulandelana kwama-attosecond, ahambisana namasekhondi angu-10^-18. Ukuze ubambe ukubaluleka okujulile kwalobu buchwepheshe, ukuqonda okuyisisekelo kokuthi i-attosecond isho ukuthini kubaluleke kakhulu. I-attosecond ime njengeyunithi yesikhathi eyiminithi eyedlulele, ehlanganisa ingxenye eyisigidigidi yengxenye yesigidi sesekhondi ngaphakathi komongo obanzi wesekhondi elilodwa. Ukuze sikuqonde lokhu, uma singafanisa umzuzwana nentaba ephakeme, i-attosecond ibingase ifane nohlamvu olulodwa lwesihlabathi olubekwe phansi kwentaba. Kulesi sikhawu sesikhashana esidlulayo, ngisho nokukhanya akukwazi ukunqamula ibanga elilingana nosayizi we-athomu ngayinye. Ngokusetshenziswa kwama-lases e-attosecond, ososayensi bathola ikhono elingakaze libonwe lokuhlolisisa futhi basebenzise amandla e-electron ayinkimbinkimbi ngaphakathi kwezakhiwo ze-athomu, okufana nokudlala kabusha okuhamba kancane kohlaka ngohlaka ngokulandelana kwesinema, ngaleyo ndlela behlolisisa ukudlala kwabo.

I-Attosecond laserszimelela umvuthwandaba wocwaningo olubanzi nemizamo ehlangene yososayensi, abasebenzise imigomo ye-nonlinear optics ukwenza ama-laser asheshayo. Ukufika kwabo kusinikeze indawo entsha yokubuka nokuhlola izinqubo eziguquguqukayo ezenzeka ngaphakathi kwama-athomu, ama-molecule, ngisho nama-electron ezintweni eziqinile.

Ukucacisa uhlobo lwamalaser e-attosecond nokwazisa izici zawo ezingajwayelekile uma kuqhathaniswa namalaser avamile, kubalulekile ukuhlola ukuhlukaniswa kwawo ngezigaba ngaphakathi "komndeni we-laser." Ukuhlelwa ngobude begagasi kubeka ama-laser e-attosecond ikakhulukazi phakathi kwebanga le-ultraviolet ukuya kumafrikhwensi athambile e-X ray, okubonisa ubude bawo beza beza obufushane ngokuphawulekayo ngokungafani nama-laser avamile. Ngokwamamodi okukhiphayo, ama-laser e-attosecond awela ngaphansi kwesigaba sama-laser ashayayo, abonakala ngobude bawo beshayela obufushane kakhulu. Ukudweba isifaniso ukuze kucace, umuntu angacabanga ama-laser amaza aqhubekayo afana nethoshi elikhipha umsebe wokukhanya oqhubekayo, kuyilapho ama-laser ashayayo afana nokukhanya kwe-strobe, ashintshana ngokushesha phakathi kwezikhathi zokukhanya nobumnyama. Empeleni, ama-laser e-attosecond abonisa indlela eshaya ngayo ngaphakathi kokukhanya nobumnyama, nokho uguquko lwawo phakathi kwalezi zifundazwe ezimbili lwenzeka ngemvamisa emangalisayo, lufinyelela endaweni yama-attosecond.

Ukuhlukaniswa okwengeziwe ngamandla kubeka ama-laser amandla aphansi, amandla aphakathi nendawo, nabakaki bamandla aphezulu. Ama-laser e-Attosecond athola amandla aphezulu ngenxa yobude bawo be-pulse emfushane kakhulu, okuholela emandleni aphakeme ashiwo (P) - achazwa njengokuqina kwamandla ngesikhathi seyunithi (P=W/t). Nakuba ama-laser attosecond laser pulses angase angabi nawo amandla amakhulu kakhulu (W), izinga lawo lesikhashana elifushanisiwe (t) liwanikeza amandla aphezulu aphezulu.

Ngokuya ngezizinda zohlelo lokusebenza, ama-laser ahlanganisa i-spectrum ehlanganisa izinhlelo zokusebenza zezimboni, zezokwelapha, nezesayensi. Ama-laser e-Attosecond ngokuyinhloko athola indawo yawo emkhakheni wocwaningo lwesayensi, ikakhulukazi ekuhloleni izinto eziguqukayo ngokushesha ngaphakathi kwezizinda zefiziksi nekhemistri, enikeza iwindi lezinqubo zezwe elishintshashintshayo le-microcosmic.

Ukuhlelwa nge-laser medium kuhlukanisa ama-laser njengamalaser egesi, ama-solid-state lasers, ama-laser liquid, nama-semiconductor lasers. Ukukhiqizwa kwama-laser e-attosecond ngokuvamile kuncike kumithombo ye-laser yegesi, kusetshenziswa imiphumela ye-optical engaqondile ukuze kusungulwe ama-harmonics e-oda eliphezulu.

Ngamafuphi, ama-laser e-attosecond akha isigaba esihlukile sama-lases ashaya kancane, ahlukaniswa ubude besilinganiso sokushaya kwenhliziyo kwawo esifushane ngokungavamile, ngokuvamile esikalwa ngama-attosecond. Ngenxa yalokho, sebephenduke amathuluzi abalulekile okubuka nokulawula izinqubo eziguquguqukayo ezisheshayo zama-electron ngaphakathi kwama-athomu, ama-molecule, nezinto eziqinile.

Inqubo Eningiliziwe ye-Attosecond Laser Generation

Ubuchwepheshe be-laser be-Attosecond buhamba phambili ekusungulweni kwesayensi, buziqhayisa ngesethi yezimo eziqinile zokukhiqiza kwabo. Ukuze sicacise ubunkimbinkimbi besizukulwane se-laser ye-attosecond, siqala ngokudalulwa kafushane kwezimiso zaso eziyisisekelo, kulandelwa izingathekiso ezicacile ezisuselwe kokuhlangenwe nakho kwansuku zonke. Abafundi abangafundile ebunkingeni befiziksi efanele akudingeki baphelelwe ithemba, njengoba izingathekiso ezilandelayo zihlose ukwenza i-foundation physics of attosecond lasers ifinyeleleke.

Inqubo yokukhiqiza yama-laser e-attosecond ngokuyinhloko incike endleleni eyaziwa ngokuthi i-High Harmonic Generation (HHG). Okokuqala, i-beam ye-high-intensity femtosecond (imizuzwana engu-10^-15) i-laser pulses igxiliswe ngokuqinile kwinto eqondiwe enegesi. Kuhle ukuqaphela ukuthi ama-laser e-femtosecond, afana namalaser e-attosecond, abelana ngezici zokuba nezikhathi ezimfishane zokushaya ngamandla kanye namandla aphezulu aphezulu. Ngaphansi kwethonya lenkambu ye-laser eqinile, ama-electron angaphakathi kwama-athomu egesi akhululwa okwesikhashana kuma-nuclei awo e-athomu, angena kancane kancane esimweni sama-electron amahhala. Njengoba lawa ma-electron ephendula inkambu ye-laser, ekugcineni abuyela futhi aphinde ahlangane ne-nuclei ye-athomu yomzali wawo, adale izifunda ezintsha ezinamandla amakhulu.

Phakathi nale nqubo, ama-electron ahamba ngesivinini esiphezulu kakhulu, futhi lapho ehlanganiswa kabusha ne-nuclei ye-athomu, akhulula amandla engeziwe ngendlela yokukhishwa kwe-harmonic ephezulu, ebonakala njengama-photon aphezulu amandla.

Amafrikhwensi alawa ma-photon asanda kukhiqizwa anamandla amakhulu ayiziphindaphinda eziphelele zefrikhwensi ye-laser yasekuqaleni, okwenza lokho okubizwa ngokuthi i-harmonics ye-high-order, lapho "i-harmonics" isho amafrikhwensi ayiziphindaphinda ezihlangene zefrikhwensi yasekuqaleni. Ukuze uthole ama-laser e-attosecond, kuyadingeka ukuthi uhlunge futhi ugxilise lawa ma-harmonics ane-oda eliphezulu, ukhethe ama-harmonics athile futhi uwagxilise endaweni okugxilwe kuyo. Uma kuthanda, izindlela zokucindezelwa kwe-pulse zingafushanisa futhi ubude be-pulse, zinikeze ama-ultra-short pulses ebangeni le-attosecond. Ngokusobala, ukukhiqizwa kwama-laser e-attosecond kuyinqubo eyinkimbinkimbi futhi enezici eziningi, efuna izinga eliphezulu lobuchwepheshe kanye nemishini ekhethekile.

Ukuqeda le nqubo eyinkimbinkimbi, sinikeza ukufanekisa okungokomfanekiso okusekelwe ezimweni zansuku zonke:

I-High-Intensity Femtosecond Laser Pulses:

Bona ngeso lengqondo uphethe ikati elinamandla elikwazi ukujikijela amatshe ngokushesha ngesivinini esikhulu, okufana nendima edlalwa umfutho we-femtosecond laser pulses.

I-Gaseous Target Material:

Bona ngeso lengqondo amanzi azolile afanekisela igesi eliqondiswe kuyo, lapho iconsi ngalinye lamanzi limelela inqwaba yama-athomu egesi. Isenzo sokuqhubezela amatshe kulo mzimba wamanzi sibonisa ngokufanayo umthelela we-high-intensity femtosecond laser pulses kwinto eqondiwe enegesi.

I-Electron Motion and Recombination (Uguquko Olumisiwe Ngokwenyama):

Lapho i-femtosecond laser pulses ithinta ama-athomu egesi ngaphakathi kwento eqondiwe yegesi, inani elibalulekile lama-electron angaphandle ajabule okwesikhashana ukuze afinyelele esimweni lapho ehlukana khona nama-nuclei awo e-athomu, akhe isimo esifana ne-plasma. Njengoba amandla ohlelo kamuva encipha (njengoba ama-laser pulses anyakaziswa ngokwemvelo, afaka izikhawu zokuyeka), lawa ma-electron angaphandle abuyela endaweni yawo ye-athomu nuclei, ekhipha ama-photon anamandla amakhulu.

High Harmonic Generation:

Cabanga nje isikhathi ngasinye lapho ithonsi lamanzi liwela phezu kwechibi, lidala ama-ripples, afana nama-harmonics aphezulu kumalaser e-attosecond. Lawa ma-ripples anamaza nama-amplitudes aphezulu kunama-ripples asekuqaleni okubangelwa i-primary femtosecond laser pulse. Phakathi nenqubo ye-HHG, i-laser beam enamandla, efana nokujikijela amatshe ngokuqhubekayo, ikhanyisa ithagethi yegesi, efana nobuso bechibi. Le nkambu ye-laser enamandla iqhubezela ama-electron kugesi, afana nokunyakaza, kude nama-athomu awo angumzali bese iwabuyisela emuva. Isikhathi ngasinye lapho i-electron ibuyela ku-athomu, ikhipha i-laser entsha ene-frequency ephezulu, efana namaphethini okugeleza ayinkimbinkimbi.

Ukuhlunga nokugxila:

Ukuhlanganisa yonke le misebe ye-laser esanda kukhiqizwa kukhiqiza i-spectrum yemibala ehlukahlukene (amafrikhwensi noma amaza wamaza), eminye yayo ehlanganisa i-laser ye-attosecond. Ukuze uhlukanise osayizi abathile be-ripple namaza, ungasebenzisa isihlungi esikhethekile, esifana nokukhetha ama-ripples oyifunayo, futhi usebenzise ingilazi yokukhulisa ukuze uwagxilise endaweni ethile.

I-Pulse Compression (uma kunesidingo):

Uma uhlose ukusabalalisa ama-ripples ngokushesha nakafushane, ungasheshisa ukusakazeka kwawo usebenzisa isisetshenziswa esikhethekile, unciphise isikhathi esihlala ngaso i-ripple ngayinye. Ukwenziwa kwama-laser e-attosecond kuhlanganisa ukusebenzisana okuyinkimbinkimbi kwezinqubo. Kodwa-ke, lapho ihlehlisiwe futhi ibonwa ngeso lengqondo, iqondakala kakhulu.