Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi
Ente Cassa di Risparmio di Firenze (No. 2014.0770A2202.8861)

Kalite Mikrokürelerinin Hiperfrekans Factor 1. Fabrikasyon <ol><li> Bir optik striptizci kullanarak akrilik kaplama kapalı bir standart tek modlu (SMF) silika fiber yaklaşık 1-2 cm şerit. </li><li> aseton ile soyulmuş kısmını temizleyin ve parçalamak. </li><li> Bir füzyon raptedici bir kolunda yarılan ucu tanıtmak ve splicer denetleyicisini kullanarak elektrik ark deşarjları bir dizi üretmek. , Splayser kontrolör menüsünden &quot;manuel işletimini&quot; seçin ark güç düzeyinde değerlerini ayarlamak ve sırasıyla 60 ve 800 msn, süreyi ark; &quot;Ark&quot; seçin ve dip &quot;+&quot; itin. </li><li> Bir küre şeklini alıyor sonra, dur 90 ° lif döndürmek ve adım 1.3 tekrarlayın. </li><li> Tekrar adım 1.3 en az 4 kez yaklaşık 160 um olan bir mikrosferdir elde edildi. yaklaşık 260 um mikroküre elde etmek için 16 kez tekrarlayın. Not: Elektrik ark deşarj silis camı kaynaştırmak için gerekli olan yüksek erime sıcaklığına üretecek. Surface gerginlik mollified lif ucundan bir sfero çekecek; Bu 19, Şekil 1 &#39;de görülebileceği gibi, küre boyutu, yaklaşık 350 um bir çapı en doygun, yay çekim sayısı ile doğru orantılıdır. dönme rezonatör küresel bir şekil temin eder. </li></ol> 2. Konik Fiber Çizim Not: şevli fiber de microresonators içine ışık bağlanması için gereklidir. mikro boyutu konik bel belirleyecektir. küre çapları daha büyük 125 mikron için konik çapı yaklaşık 3-4 mikron olabilir. küçük olanlar için, konik çapı daha küçük olmalıdır, 1-2 mikron söylüyorlar. düşük bir düzeyde kayıp tutmak ve konik bölüm sadece bir mod (temel bir) sahip olmak için, sivri adyabatik (ince bir çap kalın kademeli geçiş) olması gerekir. Adiyabatik şevli kısmın tipik toplam uzunluğu yaklaşık 2 cm&#39;dir. Figu2 yeniden fiber çekilmesi için ev yapımı cihaz ve Şekil 3A tipik bir bel bölgesi bir MicroPhoto göstermektedir. <ol><li> Şerit 3-4 optik striptizci kullanarak akrilik kaplama kapalı bir standart tek modlu (SMF) silika fiber cm ve elyaf lazer (giriş) ve bir güç ölçer (çıkış) için biter bağlayın. sıyrılmıştır bölgesi olmayan bir ucunda, elyafın ortasında yaklaşık olarak emin olun. fiber lazer ve güç metre biter bağlamak için edebilmek için bir çıplak fiber sonlandırıcı kullanın. lazer ve çalışma tezgahı üstünde güç ölçer yerleştirin. </li><li> Kısa bir alümina silindir içine soyulmuş lif ve çekme işlemi sırasında aynı anda harekete iki çeviri aşamaları içine elyaf kaplı uçlarını yerleştirin. </li><li> silis, erime noktası (yaklaşık 2.100 ° C) yakın bir sıcaklığa kadar, bir oksijen-butan alev alüminyum silindir (bu bir fırın olarak işlev yapar) ısıtın. </li><li> Obse gelen konik adiabaticity sonucuna635 nm &#39;de faaliyet gösteren bir lazer ışık iletim rvation. hiçbir mod çabalıyorlar oluştuğunu belirten sivrilen ise çıkışta homojen dairesel nokta korunmuş olup olmadığını kontrol edin. çekerek durdurmak ve iletilen güç salınım durur ve zamanla sabit olduğunda alev emekli. </li><li> Konik karşılamak için U şeklinde şekillendirilmiş bir mikroskop cam slayt olarak şevli fiber yapıştırıcı (Şekil 3B). boyutları 76x26x1.2 mm bir mikroskop cam slayt kullanın. </li></ol> Küçük Mikrokürelerinin 3. Fabrikasyon Not: kaplı standart lif büyüklüğü altında çapları küçük mikroküreler lif önceki doz azaltımı gerektirir. Bu yöntem kullanılarak elde edilen minimum çapı, yaklaşık 25 mm. <ol><li> bölüm 2 takip ederek, kırılır kadar çekerek, bir konik lif çizin. </li><li> splicer co değerleri değiştirmek, bölüm 1 (UHQ mikroküreler imalat), ancak adım 1.3 tüm adımları izleyinKontrol Ünitesiüzü beğeneceğ aşağıdaki gibi: Ark gücü 20, ark süresi 1.200 msn. </li></ol> Microsphere içine 4. Kavrama Işık Not: mikro içine çift ışığa konik kullanmak ve microresonator bir rezonans ölçün. <ol><li> 4.1. ortasında bir kanal ile bir T PVC / alüminyum tutucu hazırlayın. tutucu içine viski büyü veya kağıt yapışkan bant bir parça mikro kalan lif sapını sabitleyin. piezoelektrik aktüatör ve 20 nm bir konumlandırma çözünürlüğe sahip bir çeviri aşamasında içine iki vidayla tutucu kelepçe. </li><li> Microsphere fiber gövdeye dik konumlandırılmış slayt düzlemi ile başka çeviri aşamasına cam slayt yapıştırılmış konik sabitleyin. sonlandırılmış fiber kablolar için konik uçlarını tuttur. bir ayarlanabilir diyot lazer sonu ve bir InGaAs fotodiyot dedektöre diğerini bağlayın. </li><li> co uzun çalışma mesafesi (&gt; 20 mm) bir mikroskop tüp kullanınkonik ve mikro arasındaki boşluğu ntrol. mikrosfer ekvatora konik göreceli kontrol edilebilir pozisyon böylece tüp yönüne göre diğer yönde yer 45 ° bir ayna sistemi izlemek için. <ol><li> konik lifi ile temas mikrosfer ekvator yerleştirin. </li></ol></li><li> Lazer açın ve bir osiloskop olarak Microsphere-konik sisteminin iletim spektrumunu kontrol edin. <ol><li> rezonans görünene kadar ayar CW lazer 1.550 nm çalışan. Lorentz spektrumda dips şekilli olarak rezonanslar tespit edilebilir. </li></ol></li><li> rezonans çizgi genişliğine (Lorentz şeklindeki dip tam genişlikte yarı maksimum) ölçün. rezonans LineWidth bölü pompa sıklığı gibi Q faktörü hesaplayın. </li><li> , Küre ve konik arasındaki boşluğu artırmak / artan bağlanma verimliliğini azaltmak için rezonans genişliği ve derinliği hem değişen / azaltın. </li></ol><pclass = &quot;jove_title&quot;&gt; 5. Uyarılmış Raman Saçılma <ol><li> 1550 nm ve zayıflatıcı çalışan CW lazer arasında bir erbium katkılı fiber amplifikatör (EDFA) yerleştirin. EDFA 1,530-1,570 nm dalga boyu aralığında çalışır. . Bu yüksek giriş yetkileri 2 W. Doğrusal Olmayan etkileri maksimum çıkış gücü ihtiyacı ulaşan lazer gücünü artıracak 4 deneysel set-up bir kroki göstermektedir: Not. </li><li> 3 dBm splitter sona fiber kablolar ile konik bir ucunu. optik spektrum analizör ve osiloskop bağlı bir fotoğraf dedektöre diğerine ayırıcı çıkış liflerinin birini bağlayın. </li><li> Lazerin dalga boyu tarama hızı ile karşılaştırılabilir bir termal sürüklenme ile bir rezonans kadar ayarlayın düşük frekanslarda yüksek gelen lazer bulunur. Termal kendinden kilitli 20 elde edildiğinde rezonans genişlemesi osiloskopta görülebilir. </li><li> konik iletilen çıkış gücü kontrolbir optik spektrum analizör içine. Raman lazer çizgisi görünene kadar gücünü artırmak. Yaklaşık 13.5 THz pompa dalga boyu gelen detuned edilir. </li></ol>

<ol>
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The authors declare that they have no competing financial interests. D.F. is a PhD student at the University of Parma.

Mikroküreler kompakt ve verimli doğrusal olmayan osilatörler ve onlar imal ve işlemek için çok kolaydır. Konik elyaf bağlanması ve rezonatörün üzerine / ışık çıkarmak için de kullanılabilir. % 95&#39;e kadar rezonans kontrast ve yaklaşık 3 x 10 8 Q faktörleri elde edilebilir. Bu fabrikasyon teknikleri ana sınırlama seri üretim ve entegrasyonu. liflerin temizliğine mikroküreler ve daralan hem için kritiktir ve böylece nem. Her iki cihaz uzun süreli bir...

Fısıldayan galeri modu rezonatörler (WGMR) doğrusal olmayan fenomenler 1-3 eşik azalma sağlayan iki benzersiz özellikleri, uzun bir foton ömrü ve küçük mod hacmi göstermektedir. Fısıldayan galeri modları toplam iç yansıma yoluyla dielektrik hava arayüzü sınırlıdır optik modları vardır. zamansal hapsi boşluğunun kalite faktörü Q ile ilgilidir, oysa küçük mod hacmi yüksek uzaysal hapsi kaynaklanmaktadır. WGMR farklı geometrilere sahip olabilir ve yüksek Q Resonators böyle kaliteli faktörlerinin çevirir atomik ölçekli pürüzlülük yakın silis mikroküreler sergi olarak 4-6 Yüzey gerilimi boşlukları elde etmek için uygun farklı üretim teknikleri vardır. doğumdan her iki tip önemli ölçüde bağlı WGMR içinde güçlü bir enerji birikimine doğrusal olmayan etkiler için eşik azaltır. Aynı zamanda sürekli dalga (CW) doğrusal olmayan optik sağlar. WGMR th kullanılarak tanımlanabilirhidrojen atomu 7 ile güçlü benzer e kuantum N, L, m ve polarizasyon durumu. küresel simetri radyal ve açısal bağımlılıkları ayrılmasını sağlar. Radyal çözüm Bessel fonksiyonlarının, küresel harmonikler 8 açısal olanlar tarafından verilmektedir. Silis camı nedenle, ki-kare ile ilgili ikinci derece fenomeni (2) etkileşimleri yasaktır, centrosymmetric ve. Mikro yüzeyinde, simetri inversiyon kırılır ve Χ (2) fenomeni 1 görülmektedir. Ancak, ikinci dereceden frekans üretimi için faz eşleme koşulları dahil dalga boyları oldukça farklı ve dağılım rolü oldukça önemli olabilir, çünkü özellikle üçüncü derece frekans nesil eşdeğer daha sorunludur. ikinci dereceden etkileşim son derece zayıftır. Oysa bir thi için Q 3 ile oluşturulan güç ölçeklerrd sipariş etkileşim Q 4 ile oluşturulan güç ölçekler. 9 Bu nedenle, bu çalışmanın odak üçüncü dereceden optik doğrusal olmayan duyarlılık Χ (3) gibi Uyarılmış Raman Saçılması (SRS) ve Uyarılmış Antistokes Raman saçılımı olarak etkileşimler (SARS) &#39;dir SARS az araştırdı etkileşim 10,11 olmak. Chang 12 ve Campillo 13 derece doğrusal olmayan WGMR gibi malzemeler ancak pompa lazer yerine CW pulse edilmiştir damlacıkları kullanılarak doğrusal olmayan fenomenlerin çalışmalarını öncülük etmiştir. Silika mikroküreler 14,10 ve microtoroids 15 son yıllarda dikkat çok kazanıyor, mikro damlacıklar kıyasla daha istikrarlı ve sağlam platformlar sağladı. Özellikle silis mikro imal ve kullanımı çok kolaydır. SRS bir eşik ulaşan yeterli olduğundan kolayca silis WGMR 14,15 elde edilebilir saf kazanç süreçtir. Bu durumda, yüksek circulatiWGMR içinde yoğunluğunu ng Raman lazer uygulaması garanti, ama parametrik salınımlar için yeterli değildir. Bu gibi durumlarda, verimli titreşimler faz ve mod eşleştirme, enerji ve momentum korunumu yasası ve tüm rezonans modlarının iyi bir mekansal örtüşme 16-18 yerine getirilmesi gerekir. Bu durum, genelde SARS ve FWM için geçerlidir.

<table border="0" cellpadding="0" cellspacing="0" width="668">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical Fiber</td>
			<td style="width:93px;">Corning</td>
			<td style="width:119px;">SMF28</td>
			<td style="width:240px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fiber coating stripper</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">T06S13</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fiber cleaver</td>
			<td style="width:93px;">Fitel</td>
			<td style="width:119px;">S325A</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fusion splicer</td>
			<td style="width:93px;">Furakawa</td>
			<td style="width:119px;">S177A-1R</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Butane and Oxygen Gas</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;"></td>
			<td>any vendor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microscope tube</td>
			<td style="width:93px;">Navitar</td>
			<td style="width:119px;">Zoom 6000</td>
			<td>Modular Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CCD camera</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;">N/A</td>
			<td>any will fit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Monitor</td>
			<td style="width:93px;">n/a</td>
			<td style="width:119px;">N/A</td>
			<td>any monitor is valid</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">3-Axis Stage</td>
			<td style="width:93px;">PI Instruments, Thorlabs, Melles</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Assorted posts and mounts</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;"></td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polarization control</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">FPC030</td>
			<td>Available from other vendors as well</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Attenuator</td>
			<td style="width:93px;">Throlabs</td>
			<td style="width:119px;">VOA50</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Photodiode</td>
			<td style="width:93px;">Thorlabs</td>
			<td style="width:119px;">PDA400</td>
			<td>discontinued, replaced by PDA10CS-EC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Oscilloscope</td>
			<td style="width:93px;">Tektronix</td>
			<td style="width:119px;">DPO7104</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Optical spectrum analyzer</td>
			<td style="width:93px;">Ando</td>
			<td>AQ6317B</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Erbium Doped Fiber Amplifier</td>
			<td style="width:93px;">IPG Photonics</td>
			<td style="width:119px;">EAD-2K-C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Tunable Laser</td>
			<td style="width:93px;">Yenista</td>
			<td style="width:119px;">TUNICS</td>
			<td></td>
		</tr>
	</tbody>
</table>

stimulated stokes and antistokes raman scattering in microspherical whispering gallery mode resonators

Dielektrik mikroküreler yüksek kalite faktörü fısıldayan galeri modları arasında belirli bir süre (WGM) için ışık ve ses sınırlandırmak olabilir. kompakt lazer kaynakları, son derece hassas biyokimyasal sensörler ve doğrusal olmayan fenomenler: cam mikro uygulamalar büyük bir çeşitlilik ile bir enerji deposu olarak düşünülebilir. mikrosferler ve bağlantı sisteminin, hem imalatı için bir protokol verilmektedir. Burada anlatılan kuplörler konik lifler bulunmaktadır. Üçüncü dereceden optik doğrusal olmayan duyarlılık ile ilgili doğrusal olmayan olayların etkili nesil Χ (3) triply rezonans silis mikrosferlerdeki etkileşimler bu yazıda sunulmuştur. bildirilen burada etkileşimler şunlardır: Uyarılmış Raman saçılması (SRS) ve Uyarılmış Anti-Stokes Raman Saçılma (SARS) içeren dört dalga karıştırma işlemleri. boşluğu geliştirilmiş olgusunun bir dayanıklı pompa, sinyal ve avara arasındaki korelasyonun olmaması ile elde edilir: bir rezonant mod çifti elde etmek için ana kadar zorundadırsinyal ve avara. hyperparametric salınımlarının durumunda (dört dalga karıştırma ve uyarılmış anti-Stokes Raman saçılması) ise, modlar, enerji ve momentum korunumu yerine getirmek ve son ama en az değil, iyi bir mekansal örtüşme olmalıdır.

Mikro-Q faktörleri protokolü, yukarıda tarif edilen geniş çaplı 10 8 (Şekil 5) (&gt; 200 um) aşan ve küçük çaplar için 10 6 (&lt;50 um) aşan Aşağıdaki üretti. (Kritik bağlantı yakın)% 95 üzerinde rezonans kontrast kolaylıkla görülebilir. Yüksek dolaşan şiddetleri için kızılötesi bölgede aşağıdaki doğrusal olmayan etkiler görülebilir: (SRS) uyarılmış Raman saçılması, SRS 21 basamaklı anti-Stoke...

Watch this Scientific Journal Video about Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators at JoVE.com

Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Mikrosferik Whispering Galeri Modu Rezonatörler içinde Uyarılmış Stokes ve Antistokes Raman saçılması

Üçüncü dereceden optik doğrusal olmayan duyarlılık ile ilgili doğrusal olmayan olayların etkili nesil Χ (3) triply rezonans silis mikrosferlerdeki etkileşimler bu yazıda sunulmuştur. bildirilen burada etkileşimler şunlardır: Uyarılmış Raman saçılması (SRS) ve Uyarılmış Anti-Stokes Raman Saçılma (SARS) içeren dört dalga karıştırma işlemleri.

Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres ...

stimulated-stokes-antistokes-raman-scattering-microspherical

Research

JoVE Journal

Engineering

11.2K Görüntüleme.  Enrico Fermi Center.  Üçüncü dereceden optik doğrusal olmayan duyarlılık ile ilgili doğrusal olmayan olayların etkili nesil Χ (3) triply rezonans silis mikrosferlerdeki etkileşimler bu yazıda sunulmuştur. bildirilen burada etkileşimler şunlardır: Uyarılmış Raman saçılması (SRS) ve Uyarılmış Anti-Stokes Raman Saçılma (SARS) içeren dört dalga karıştırma işlemleri. 

Video: Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

Galeri Modu Polimerik Mikro-optik Elektrik Alan Sensörleri Whispering Gelişimi

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

Mühendislik

Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

The customized techniques developed in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators are presented. The protocols to obtain and characterize these resonators are detailed, and an explanation of some of their applications in microwave photonics is given.

Mikrodalga Fotonik Sistemleri Whispering-galeri-mod Rezonatörler dayanarak

Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various ...

Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets during dissolution while UV absorption spectroscopy is simultaneously providing inline analysis of dissolved drug concentration for tablets containing a 50% mixture of theophylline anhydrate and ethyl cellulose. The measurements showed that in situ CARS microscopy is capable of imaging selectively theophylline in the presence of ethyl cellulose. Additionally, the theophylline anhydrate converted to theophylline monohydrate during dissolution, with needle-shaped crystals growing on the tablet surface during dissolution. The conversion of theophylline anhydrate to monohydrate, combined with reduced exposure of the drug to the flowing dissolution medium resulted in decreased dissolution rates. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring pharmaceutical tablet dissolution and correlating surface changes with changes in dissolution rate.

Coherent anti-Stokes Raman Scattering CARS Microscopy Visualizes Pharmaceutical Tablets During Dissolution

Coherent anti-Stokes Raman scattering (CARS) microscopy is combined with an intrinsic flow-through dissolution setup to allow in situ and real-time visualization of the surface of pharmaceutical tablets undergoing dissolution. Using this custom-built setup, it is possible to correlate CARS videos with drug dissolution profiles recorded using inline UV absorption spectroscopy.

Çözünme sırasında tutarlı bir anti-Stokes Raman saçılması (CARS) Mikroskopi visualizes İlaç Tabletler

Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This ...

Resonance Raman Spectroscopy of Extreme Nanowires and Other 1D Systems

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the presence of carbon nanotubes. These nanowires are extreme in the sense that they are the limit of miniaturization of nanowires and their behavior is not always a simple extrapolation of the behavior of larger nanowires as their diameter decreases. The paper then describes the methods required to obtain Raman spectra from extreme nanowires and the fact that due to the van Hove singularities that 1D systems exhibit in their optical density of states, that determining the correct choice of photon excitation energy is critical. It describes the techniques required to determine the photon energy dependence of the resonances observed in Raman spectroscopy of 1D systems and in particular how to obtain measurements of Raman cross-sections with better than 8% noise and measure the variation in the resonance as a function of sample temperature. The paper describes the importance of ensuring that the Raman scattering is linearly proportional to the intensity of the laser excitation intensity. It also describes how to use the polarization dependence of the Raman scattering to separate Raman scattering of the encapsulated 1D systems from those of other extraneous components in any sample.

The paper describes a method for producing extreme nanowires by melt infiltration into carbon nanotubes and how 1D systems may be characterized and investigated using Resonance Raman Spectroscopy to determine vibrational and optical excitation energies.

Aşırı Nanotel ve Diğer 1D Sistemleri Rezonans Raman Spektroskopisi

This paper briefly describes how nanowires with diameters corresponding to 1 to 5 atoms can be produced by melting a range of inorganic solids in the ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

Süperiletken Rezonatörler Fabrikasyon ve Karakterizasyonu

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the ALD process, which has an accuracy of 0.1 nm.

A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.

Terahertz Metamalzemeler de Yerdeğiştirme Akımı aracılığı Rezonansları için Nanopillar Tabanlı Bölünmüş Yüzük Rezonatörler Fabrikasyon

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

Scanning Light Scattering Profiler (SLPS) Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light scattering from intraocular lenses (IOLs) using goniophotometer principles. This protocol describes the SLSP platform and how it employs a 360&#176; rotational photodetector sensor that is scanned around an IOL sample while recording the intensity and location of scattered light as it passes through the IOL medium. The SLSP platform can be used to predict, non-clinically, the propensity for current and novel IOL designs and materials to induce light scatter. Non-clinical evaluation of light scattering properties of IOLs can significantly reduce the number of patient complaints related to unwanted glare, glistening, optical defects, poor image quality, and other phenomena associated with the unintended light scattering. Future studies should be conducted to correlate SLSP data with clinical results to help identify which measured light scatter is most problematic for patients that have undergone cataract surgery subsequent to IOL implantation.

Scanning Light Scattering Profiler SLPS Based Methodology to Quantitatively Evaluate Forward and Backward Light Scattering from Intraocular Lenses

This protocol describes the scanning light scattering profiler (SLSP) that enables the full-angle quantitative evaluation of forward and backward scattering of light from intraocular lenses (IOLs) using goniophotometer principles.

Işık saçılma Profiler (SLPS) Tabanlı Metodoloji İntraoküler Lenslerden İleri ve Geri Işık Saçılımını Kantitatif Olarak Değerlendirmek İçin Tarama

The scanning light scattering profiler (SLSP) methodology has been developed for the full-angle quantitative evaluation of forward and backward light ...

High-speed Continuous-wave Stimulated Brillouin Scattering Spectrometer for Material Analysis

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as aqueous solutions and biomaterials, with fast acquisition times. Here, we discuss the assembly and operation of a Brillouin spectrometer that uses stimulated Brillouin scattering (SBS) to measure stimulated Brillouin gain (SBG) spectra of water and lipid emulsion-based tissue-like samples in transmission mode with &lt;10 MHz spectral-resolution and &lt;35 MHz Brillouin-shift measurement precision at &lt;100 ms. The spectrometer consists of two nearly counter-propagating continuous-wave (CW) narrow-linewidth lasers at 780 nm whose frequency detuning is scanned through the material Brillouin shift. By using an ultra-narrowband hot rubidium-85 vapor notch filter and a phase-sensitive detector, the signal-to-noise-ratio of the SBG signal is significantly enhanced compared to that obtained with existing CW-SBS spectrometers. This improvement enables measurement of SBG spectra with up to 100-fold faster acquisition times, thereby facilitating high spectral-resolution and high-precision Brillouin analysis of soft materials at high speed.

We describe the construction of a rapid continuous-wave-stimulated-Brillouin-scattering (CW-SBS) spectrometer. The spectrometer employs single-frequency diode-lasers and an atomic vapor notch-filter to acquire transmission spectra of turbid/non-turbid samples with high spectral-resolution at speeds up to 100-fold faster than those of existing CW-SBS spectrometers. This improvement enables high-speed Brillouin material analysis.

Yüksek hızda sürekli uyarılan Brillouin saçılma Spektrometre için malzeme analizi

Recent years have witnessed a significant increase in the use of spontaneous Brillouin spectrometers for non-contact analysis of soft matter, such as ...

Ultrasonic Fatigue Testing in the Tension-Compression Mode

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on exposing the specimen to longitudinal vibrations on its resonance frequency close to 20 kHz. With use of this method, it is possible to significantly decrease the time required for the test, when compared to conventional testing devices usually working at frequencies under 200 Hz. It is also used to simulate loading of material during operation in high speed conditions, such as those experienced by components of jet engines or car turbo pumps. It is necessary to operate only in the high and ultra-high cycle region, due to the possibility of extremely high deformation rates, which can have a significant influence on the test results. Specimen shape and dimensions have to be carefully selected and calculated to fulfill the resonance condition of the ultrasonic system; thus, it is not possible to test the full components or specimens of arbitrary shape. Before each test, it is necessary to harmonize the specimen with the frequency of the ultrasonic system to compensate for deviations of the real shape from the ideal one. It is not possible to run a test until a total fracture of the specimen, since the test is automatically terminated after initiation and propagation of the crack to a certain length, when the stiffness of the system changes enough to shift the system out of the resonance frequency. This manuscript describes the process of evaluation of materials' fatigue properties at high-frequency ultrasonic fatigue loading with use of mechanical resonance at a frequency close to 20 kHz. The protocol includes a detailed description of all steps required for a correct test, including specimen design, stress calculation, harmonizing with the resonance frequency, performing the test, and final static fracture.

A protocol for ultrasonic fatigue testing in the high and ultra-high cycle region in axial tension-compression loading mode.

Ultrasonik yorgunluk gerginlik-sıkıştırma modunda test

Ultrasonic fatigue testing is one of a few methods which allow investigating fatigue properties in the ultra-high cycle region. The method is based on ...

Scattering And Absorption of Light in Planetary Regoliths

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed microscopic particles. The theoretical and numerical methods constitute a framework of Radiative Transfer with Reciprocal Transactions (R2T2). The R2T2 framework entails Monte Carlo order-of-scattering tracing of interactions in the frequency space, assuming that the fundamental scatterers and absorbers are wavelength-scale volume elements composed of large numbers of randomly distributed particles. The discrete random media are fully packed with the volume elements. For spherical and nonspherical particles, the interactions within the volume elements are computed exactly using the Superposition T-Matrix Method (STMM) and the Volume Integral Equation Method (VIEM), respectively. For both particle types, the interactions between different volume elements are computed exactly using the STMM. As the tracing takes place within the discrete random media, incoherent electromagnetic fields are utilized, that is, the coherent field of the volume elements is removed from the interactions. The experimental methods are based on acoustic levitation of the samples for non-contact, non-destructive scattering measurements. The levitation entails full ultrasonic control of the sample position and orientation, that is, six degrees of freedom. The light source is a laser-driven white-light source with a monochromator and polarizer. The detector is a mini-photomultiplier tube on a rotating wheel, equipped with polarizers. The R2T2 is validated using measurements for a mm-scale spherical sample of densely-packed spherical silica particles. After validation, the methods are applied to interpret astronomical observations for asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko (Figure 1) recently visited by the NASA Dawn mission and the ESA Rosetta mission, respectively.

Numerical and experimental methods are presented for multiple scattering of light in discrete random media of densely-packed particles. The methods are utilized to interpret the observations of asteroid (4) Vesta and comet 67P/Churyumov-Gerasimenko.

Gezegen Regoliths ışık saçılma ve emilimi

Theoretical, numerical, and experimental methods are presented for multiple scattering of light in macroscopic discrete random media of densely-packed ...