Isishwankathelo se-pulsed lasers

Isishwankathelo seiileza ezishukumayo

Eyona ndlela ithe ngqo yokwenzailezaiipulses zezokongeza i-modulator ngaphandle kwe-laser eqhubekayo. Le ndlela inokuvelisa i-picosecond pulse ekhawulezayo, nangona ilula, kodwa amandla okukhanya alahlekileyo kunye namandla e-peak awakwazi ukudlula amandla okukhanya aqhubekayo. Ke ngoko, indlela esebenza ngakumbi yokwenza ii-laser pulses kukuguqula kwi-laser cavity, ukugcina amandla ngexesha elingekhoyo le-pulse train kwaye uyikhuphe ngexesha. Iindlela ezine eziqhelekileyo ezisetyenziselwa ukuvelisa ii-pulses nge-laser cavity modulation kukutshintsha i-gain switching, i-Q-switching (i-loss switching), i-cavity empting, kunye ne-mode-locking.

I-gain switch ivelisa ii-short pulses ngokuguqula amandla epompo. Umzekelo, ii-semiconductor gain-switched lasers zinokuvelisa ii-pulses ukusuka kwi-nanoseconds ezimbalwa ukuya kwi-picoseconds ezilikhulu nge-current modulation. Nangona amandla e-pulse ephantsi, le ndlela iguquguquka kakhulu, njengokubonelela nge-adjustable repetition frequency kunye nobubanzi be-pulse. Ngo-2018, abaphandi kwiYunivesithi yaseTokyo baxele nge-femtosecond gain-switched semiconductor laser, emele impumelelo kwi-bottleneck yobugcisa yeminyaka engama-40.

Iipulse ze-nanosecond ezinamandla zihlala ziveliswa zii-laser ze-Q-switched, ezikhutshwa kwii-round trips ezininzi kwi-cavity, kwaye amandla e-pulse akwi-millijoules ezininzi ukuya kwii-joules ezininzi, kuxhomekeke kubukhulu benkqubo. Amandla aphakathi (ngokubanzi angaphantsi kwe-1 μJ) ii-picosecond kunye nee-femtosecond pulses ziveliswa kakhulu zii-laser ezivaliweyo kwi-mode. Kukho iipulse ezimfutshane ezimfutshane kwi-laser resonator ezijikeleza ngokuqhubekayo. I-pulse nganye ye-intracavity idlulisela i-pulse ngesibuko sokudibanisa esiphumayo, kwaye i-refrequency ngokubanzi iphakathi kwe-10 MHz kunye ne-100 GHz. Umfanekiso ongezantsi ubonisa i-full normal dispersion (ANDi) dissipative soliton femtosecond.isixhobo se-fiber laser, uninzi lwazo lunokwakhiwa kusetyenziswa izinto ezisemgangathweni zeThorlabs (ifayibha, ilensi, i-mount kunye netafile yokufuduka).

Indlela yokukhupha imingxunya ingasetyenziselwaIileyiza ezitshintshiweyo nge-Qukufumana iipulses ezimfutshane kunye nee-laser ezivaliweyo zemowudi ukwandisa amandla e-pulse ngokuphindaphinda okuphantsi.

Iipulses zedomeyini yexesha kunye neefrequency zedomeyini
Imilo ethe tye ye-pulse ngokuhamba kwexesha ilula kakhulu kwaye inokubonakaliswa ngemisebenzi yeGaussian kunye ne-sech². Ixesha le-pulse (ekwaziwa ngokuba yi-pulse width) libonakaliswa kakhulu yixabiso le-half-height width (FWHM), oko kukuthi, ububanzi apho amandla okukhanya angaphezulu kwesiqingatha samandla aphezulu; i-Q-switched laser ivelisa ii-nanosecond short pulses ngokusebenzisa
Iileser ezivaliweyo zeMode zivelisa iipulse ezimfutshane kakhulu (i-USP) ngokulandelelana kwamashumi eepicoseconds ukuya kwifemtoseconds. Ii-elektroniki ezikhawulezayo zinokulinganisa kuphela amashumi eepicoseconds, kwaye iipulse ezimfutshane zinokulinganiswa kuphela ngobuchwepheshe bokukhanya obufana nee-autocorrelators, iFROG kunye neSPIDER. Nangona iipulse ze-nanosecond okanye ezinde zingatshintshi ububanzi bepulse yazo njengoko zihamba, nokuba kumgama omde, iipulse ezimfutshane kakhulu zinokuchaphazeleka zizinto ezahlukeneyo:

Ukusasazeka kunokubangela ukwanda kwe-pulse enkulu, kodwa kunokucinezelwa kwakhona ngokusasazeka okwahlukileyo. Lo mzobo ulandelayo ubonisa indlela i-Thorlabs femtosecond pulse compressor ehlawulela ngayo ukusasazeka kwe-microscope.

Ukungangqamani ngokubanzi akuchaphazeli ngokuthe ngqo ububanzi be-pulse, kodwa kuyayikhulisa i-bandwidth, okwenza i-pulse ibe sesichengeni sokusasazeka ngexesha lokusasazeka. Naluphi na uhlobo lwefayibha, kuquka nezinye izixhobo zokufumana i-bandwidth ezilinganiselweyo, zinokuchaphazela imo ye-bandwidth okanye i-ultra-short pulse, kwaye ukwehla kwe-bandwidth kunokukhokelela ekwandeni kwexesha; Kukwakho neemeko apho ububanzi be-pulse ye-pulse etshixileyo kakhulu buba mfutshane xa i-spectrum iba ncinci.