Musamman ultrafast Laser part one

Na musammanultrafast Laserkashi na daya

Musamman kaddarorin ultrafastLaser
Matsakaicin gajeriyar bugun bugun jini na laser ultrafast yana ba waɗannan tsarin kaddarorin kaddarorin da ke bambanta su daga laser mai tsayi ko ci gaba (CW). Domin samar da irin wannan ɗan gajeren bugun bugun jini, ana buƙatar bandwidth mai faɗi mai faɗi. Siffar bugun jini da tsayin raƙuman ruwa na tsakiya sun ƙayyade mafi ƙarancin bandwidth da ake buƙata don samar da bugun jini na wani lokaci na musamman. Yawanci, ana siffanta wannan dangantakar ta hanyar samfurin lokaci-bandwidth (TBP), wanda aka samo daga ƙa'idar rashin tabbas. Ana ba da TBP na bugun bugun Gaussian ta hanyar dabara mai zuwa: TBPGaussian = ΔτΔν≈0.441
Δτ shine tsawon lokacin bugun jini kuma Δv shine bandwidth mitar. Ainihin, ma'auni yana nuna cewa akwai wata dangantaka mai banƙyama tsakanin bandwidth bakan da tsawon lokaci, ma'ana cewa yayin da tsawon lokacin bugun jini ya ragu, bandwidth da ake buƙata don samar da wannan bugun jini yana ƙaruwa. Hoto na 1 yana kwatanta mafi ƙarancin bandwidth da ake buƙata don tallafawa lokuta daban-daban na bugun bugun jini.

Hoto 1: Ƙananan bandwidth na gani da ake buƙata don tallafawaLaser bugun jinina 10ps (kore), 500 fs (blue), da 50 fs (ja)

Kalubalen fasaha na laser ultrafast
Faɗin bandwidth mai faɗi, ƙarfin kololuwa, da ɗan gajeren lokacin bugun jini na laser ultrafast dole ne a sarrafa shi da kyau a cikin tsarin ku. Sau da yawa, ɗayan mafi sauƙin mafita ga waɗannan ƙalubalen shine babban fitarwa na laser. Idan da farko kun yi amfani da dogon bugun bugun bugun jini ko na'urorin laser masu ci gaba da gudana a baya, abubuwan da kuke da su na kayan aikin gani bazai iya yin tunani ko watsa cikakken bandwidth na ultrafast pulses.

Ƙofar lalacewar Laser
Ultrafast optics suma suna da mabambanta sosai kuma sun fi wahalar kewaya iyakokin lalacewa ta Laser (LDT) idan aka kwatanta da ƙarin hanyoyin laser na al'ada. Lokacin da aka samar da na'urorin ganinanosecond pulsed Laser, Ƙimar LDT yawanci suna cikin tsari na 5-10 J/cm2. Don ultrafast optics, ƙimar wannan girman kusan ba a taɓa jin su ba, saboda ƙimar LDT tana iya kasancewa akan tsari na <1 J/cm2, yawanci kusa da 0.3 J/cm2. Babban bambancin girman LDT a ƙarƙashin nau'ikan bugun jini daban-daban shine sakamakon injin lalata laser dangane da tsawon lokacin bugun jini. Don nanosecond lasers ko ya fi tsayipulsed lasers, Babban hanyar da ke haifar da lalacewa shine dumama thermal. A shafi da kuma substrate kayan nana'urorin ganisha photons da ya faru da kuma dumama su. Wannan na iya haifar da murdiya daga lattice na kayan. Fadada yanayin zafi, tsagewa, narkewa da ɗimbin lattice sune hanyoyin lalata yanayin zafi gama gari na waɗannantushen laser.

Duk da haka, don laser ultrafast, tsawon lokacin bugun jini da kansa ya fi sauri fiye da lokacin sikelin zafi daga Laser zuwa lattice kayan aiki, don haka tasirin thermal ba shine babban dalilin lalacewar laser ba. Madadin haka, ƙarfin kololuwar laser ultrafast yana canza tsarin lalacewa zuwa hanyoyin da ba na kan layi ba kamar ɗaukar hoto da yawa da ionization. Wannan shine dalilin da ya sa ba zai yiwu a rage ma'aunin LDT na bugun bugun nanosecond kawai zuwa na bugun bugun jini ba, saboda tsarin jiki na lalacewa ya bambanta. Don haka, a ƙarƙashin sharuɗɗan amfani iri ɗaya (misali, tsayin tsayi, tsawon bugun bugun jini, da ƙimar maimaitawa), na'urar gani mai cikakkiyar ƙimar LDT zata zama mafi kyawun na'urar gani don takamaiman aikace-aikacenku. Na'urorin gani da aka gwada a ƙarƙashin yanayi daban-daban ba su wakiltar ainihin aikin na'urorin gani iri ɗaya a cikin tsarin ba.

Hoto 1:Hanyoyin Laser lalacewa tare da lokuta daban-daban na bugun jini