Hanyoyin Zane na Bessel Beam

Domin a narke kayan da ke ɓangarorin biyu na haɗin gwiwa a lokaci guda da kuma kafa haɗin ƙananan yankuna masu ƙarfi, dole ne a mayar da hankali kan wurin da laser ke mayar da hankali a kai daidai kan samfurin, wanda ke sanya buƙatu masu tsauri kan daidaiton sarrafa tsarin walda. Bugu da ƙari, saboda babban ƙarfin axial na hasken Gaussian bayan an mayar da hankali, zafin filin mai da hankali bai daidaita ba, wanda hakan ke sa ya zama da sauƙin haifar da lahani na ƙananan da nano a yankin da laser ya shafa, wanda hakan ke shafar ingancin walda na samfurin.

Ana iya amfani da fasahar siffanta haske ta sarari don samar da hasken Bessel mara tsari don inganta rarrabawar ƙarfin filin mai da hankali na laser. Wannan hanyar tana rage saurin ƙarfin axial kuma tana faɗaɗa tsawon mai da hankali, ta haka tana ƙara rabon zurfin-zuwa-faɗi na yankin tasirin zafi da laser ya samar. Sakamakon haka, yana rage buƙatun daidaiton mai da hankali na tsarin walda na laser, yana inganta ingancin walda da inganci.

1. Tsarin Tsarawa da Sigogi na Bessel Beams marasa Rarrabawa

A shekarar 1987, Durnin ya fara gabatar da hasken Bessel mai tsari sifili, wanda ke nuna halaye na musamman marasa bambanci: yawan hasken da ke ratsawa ba ya canzawa yayin yaduwa, kuma girman wurin tsakiyar yana kusa da iyakar diffraction. Bugu da ƙari, hasken Bessel kuma yana nuna ikon warkar da kansa yayin yaduwa. Lokacin da aka toshe wurin tsakiyar, hasken da ke kewaye zai haɗu zuwa tsakiya don "gyara" wurin tsakiyar. Ma'anar lissafi don rarraba filin haske mai tsari sifili na hasken Bessel shine:

A cikin furucin:

• J0 yana wakiltar aikin Bessel mai tsari sifili.
• r da φ sune abubuwan daidaitawa na radial da kusurwa, bi da bi.
• z shine nisan yaɗuwa.
• Kr da Kz sune abubuwan da ke jujjuyawar da kuma na tsawon lokaci.

Babban wurin da aka gina katakon Bessel mai sifili yana da ƙarfin ɗaurewa mai ƙarfi, wanda ke ba da damar matakan hasken wuta na TW/cm² ko sama da haka, wanda zai iya tayar da shaye-shaye marasa layi a cikin kayan. Mafi mahimmanci, halayyar yaɗuwar katakon Bessel mai sifili ba ta bambanta ba tana ba da zurfin mayar da hankali da ƙaramin juzu'i na ƙarfin axial, don haka yana ƙirƙirar filin zafin da ya yi daidai da juna kuma yana hana samuwar lahani na walda.

Hoto mai zuwa yana nuna kwatancen tsawon mai da hankali na haskokin Bessel da Gaussian a ƙarƙashin ikon ɗaurewa iri ɗaya. Haskokin Bessel suna da zurfin mai da hankali sosai yayin da suke riƙe da diamita na wurin da aka fi mayar da hankali na micron.

Akwai hanyoyi da dama na samar da hasken Bessel mai tsari sifili, kuma manyan hanyoyi guda uku masu zuwa sun zama ruwan dare:

Hanyar Buɗewar Annular: Hanyar buɗewar annular, kamar yadda sunan ya nuna, ta ƙunshi amfani da buɗewar annular don samar da buɗewar Bessel. Wannan kuma ita ce hanya ta farko da ta yi nasara wajen samar da buɗewar Bessel. Zane da ke ƙasa yana nuna hanyar buɗewar annular don samar da buɗewar Bessel. Raƙuman jirgin sama suna faruwa ne a tsaye a kan buɗewar annular daga hagu kuma diffraction yana faruwa.

Bayan haka, ruwan tabarau mai kyau yana yin canjin Fourier, wanda ke haifar da samuwar hasken Bessel a bayan ruwan tabarau. Nisa mai yaduwa mara bambanci Zmax yana da alaƙa da diamita d na tsagawar annular da kuma buɗewar lambobi na ruwan tabarau.

Duk da cewa wannan hanyar za ta iya samar da hasken Bessel mara tsari, ingancin canza makamashi yana da ƙasa sosai, wanda hakan ke sa ya yi wuya a yi amfani da shi a fannonin sarrafa laser.

Hanyar Daidaita Hasken Sararin Samaniya: Tsarin samar da hasken Bessel mai tsari sifili tsari ne na canza rarrabawar lokaci na hasken. Saboda haka, ana iya samar da hasken Bessel mai tsari sifili ta amfani da na'urar daidaita hasken sarari. Na'urar daidaita hasken sarari nau'in na'urar daidaita hasken optoelectronic ce wadda ke sarrafa ƙarfin filin haske da rarrabawar lokaci ta hanyar siginar lantarki. Ana iya samar da hasken Bessel mai tsari sifili ta hanyar amfani da yanayin ruwan tabarau mai siffar mazugi, kamar yadda aka nuna a hoton da ke ƙasa, zuwa ga allon aiki na na'urar daidaita hasken sarari.

Hanyar Axicon: Axicon yana ɗaya daga cikin abubuwan da aka fi amfani da su wajen samar da hasken Bessel. Idan hasken Gaussian ya saba faruwa kuma ya ratsa ta cikin axicon, ana daidaita rarrabawarsa ta lokaci, yana mayar da shi hasken Bessel mai tsari sifili ba tare da asarar kuzari ba, kamar yadda aka nuna a cikin hoton da ke ƙasa.

Saboda ƙarancin farashi, sauƙin amfani, da kuma yawan lalacewar laser na axicons na gilashi, da kuma ingancin amfani da makamashi mai yawa, axicons sune babban zaɓi don samar da axions na Bessel a fannin sarrafa laser. Hoton da ke ƙasa yana nuna tsarin rage hasken da watsa hasken Bessel mai tsari sifili. Ta hanyar daidaita girman da yanayin tsarin hoton 4f, ana iya sarrafa nisan yaɗuwar da ba ta bambanta ba, kusurwar rabin mazugi, da kusurwar karkatarwa a cikin alkiblar yaɗuwar hasken Bessel cikin sauƙi.

Idan hasken Bessel mai siffar sifili mai kusurwar rabin mazugi na Ɵ1 da nisan yaɗuwa mara diffraction na Zmax ya ratsa ta tsarin 4f wanda ya ƙunshi ruwan tabarau (L1) da ruwan tabarau na zahiri (L2), za a ƙara matse girman siffar geometric. Girman gefen shine kusan M=f1/f2=5, kuma girman tsayin shine kusan M2=25. Don haka, hoton ƙarshe na hasken Bessel mai siffar sifili a cikin samfurin za a iya wakilta shi ta hanyar sigogin geometric:

Sigogi na geometric na bes ɗin Bessel da aka zana a cikin samfurin gilashin quartz a ƙarƙashin kusurwoyi daban-daban na mazugi da girman matsi na katako.

Rarraba ƙarfin filin mai da hankali na hasken Bessel

• r da z: Abubuwan haɗin kai na radial da axial, bi da bi.
• λ: Tsawon tsayin laser na tsakiya.
• w: radius 1/e² na abin da ya faru Hasken Gaussian.
• P0: Ƙarfin ƙarfin laser mai gajere.
• β1: Kusurwar rabin-mazugi ta bessel bayan matsewar beads.
• k: Vektor mai motsi.
• J0: Aikin Bessel mai tsari sifili.

Rarraba ƙarfi na hasken Bessel mai tsari sifili a cikin gilashin quartz: A hagu akwai rarrabawar yawan ƙarfin gani tare da alkiblar yaɗawa da kuma kallon giciye, kuma a dama akwai rarrabawar yawan ƙarfin gani tare da axis da kuma kallon giciye

2. Halayen Femtosecond Pulse Bessel Beam a cikin Gilashin Silica da aka Haɗa

Hoto (a) yana nuna ƙananan hotunan hulɗar da ke tsakanin hasken femtosecond pulse beams Bessel da gilashin silica da aka haɗa a cikin ƙarfin bugun jini daban-daban. Faɗin bugun laser an daidaita shi a 220 fs, kuma kusurwar rabin mazugi na hasken Bessel da ke cikin samfurin shine 12.4°. Ana iya lura cewa yankin da laser ya shafa yana nuna tsarin layi na yau da kullun mai girma ɗaya. Lokacin da ƙarfin bugun laser ya ƙasa da 9.5 μJ, ma'aunin refractive na kayan da ke cikin yankin mai da hankali yana ƙaruwa, yana bayyana a matsayin yanki baƙi a cikin hasken micrograph.

Idan ƙarfin bugun laser ya wuce 9.5 μJ, ma'aunin refractive na kayan da ke yankin tsakiya ya ragu, yana bayyana a matsayin yankin fari a cikin micrograph, kuma tsawon yankin fari yana ƙaruwa tare da ƙaruwar kuzarin bugun. Ta hanyar goge samfurin, mun lura da halayen yanayin yankin fari a ƙarfin bugun 15.4 μJ a ƙarƙashin na'urar duba na'urar lantarki, kamar yadda aka nuna a Hoto (b). Za a iya kammala da cewa an samar da nanopore mai diamita kusan 200 nm a yankin tare da raguwar ma'aunin refractive.

Ta hanyar amfani da tsarin ion beam etching da kuma tsarin lura da na'urar hangen nesa ta electron microscope, mun ƙara tabbatar da kasancewar nanopore ɗin (Hoto na c). Saboda haka, domin rage samar da lahani da laser ke haifarwa, ƙarfin bugun jini ɗaya bai kamata ya wuce 9.5 μJ ba yayin walda ta laser.

3. Samun Ingantaccen Walda Tsakanin Gilashin Silica Mai Haɗawa Ta Amfani da Laser na Bessel Ultrashort Pulse.

Hoto (a) yana nuna ƙaramin hoton saman saman walda na samfurin. Ana iya ganin cewa layin walda na laser yana da daidaito kuma santsi. Duk da cewa har yanzu akwai wasu ƙananan lahani na ƙananan ramuka a yankin walda, gabaɗaya, ya fi layin walda na laser na Gaussian kyau sosai. Ma'auni sun nuna cewa faɗin layin walda yana da kusan μm 18, kuma tazara tsakanin layin walda shine 40 μm. Hoto (b) yana nuna ƙaramin hoton gefen layin walda na samfurin.

Ana iya ganin cewa tazarar da ke tsakanin samfuran ta ɓace gaba ɗaya bayan an sarrafa laser, kuma kayan da ke kusa da mahaɗin sun haɗu cikin abu ɗaya bayan an yi aikin narkewar zafi da sanyaya zafi. Ma'auni sun nuna cewa zurfin yankin narkewar zafi da laser ke haifarwa ya kai har zuwa 227 μm. Wannan yana nuna cewa yayin walda laser tare da waɗannan sigogi, zurfin axial na matsayin mai da hankali zai iya kaiwa har zuwa 227 μm, wanda ya ninka sau huɗu na walda laser Gaussian a ƙarƙashin yanayi iri ɗaya.

4. Ina Za a Sayi Ruwan Gilashin Bessel?

Wavelength Opto-Electronic yana ba da ruwan tabarau na Bessel masu inganci waɗanda ake amfani da su a aikace-aikacen sarrafa laser. Canza zurfin mayar da hankali na hasken fitarwa ta hanyar daidaita girman diamita na hasken shigarwa shine mafi kyawun fasalin wannan tsarin hasken Bessel.