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In this study, we report that the thermal treatment effects on the Raman and photoluminescence (PL) spectra of mono and few-layer MoS2 films by annealing in the vacuum and air at 300ºC, respectively. The MoS2 film samples were prepared on silicon substrate by exfoliating from a bulk MoS2 crystal with a micromechanical exfoliation. For characterization of structural properties of the MoS2 films and identification of the Raman active modes, Raman spectrometer equipped with a He-Ne laser source and an optical microscope has been used. The results show that the vacuum annealing 7L MoS2 decreases the Full Width at Half Maximum (FWHM) of the Raman active modes as E1 2g, A1g and the vacuum annealing 1L MoS2 increases the PL intensity and peak energy, for 60% and 13.3meV, respectively also air annealing bilayer MoS2 increased the PL intensity (IA) and peak energy (EA), respectively for 85% and 15.4 meV (3000 C for 40 min). After thermal annealing (vacuum and air), we observe that the indirect bandgap of the few-layer MoS2 was changed.
We have successfully constructed a Kerr lens mode-locked (KLM) Ti:sapphire oscillator to generate ultrashort pulses of ~18 fs. The oscillator consists of only 5 elements including a pair of double-chirped mirrors to balance negative group delay dispersion in the cavity. The bandwidth of the mode-locked laser oscillator spectrum is from 600 nm to 950 nm and pulse energy is 1.5 nJ. Both the output spectrum and the output power were stable against environmental disturbance. For the pulse characterization, a second harmonic generation frequency resolved optical gating method was used.
Thickness optimization of a monometallic plasmonic structure for a surface-plasmon resonance biosensor
Surface-plasmon resonance (SPR) effect in thin metal films is highly sensitive to the dielectric refractive index changes in the vicinity of metal interface and the conventional Kretschmann configuration has been widely used in the SPR measurement. In this work we have presented the thickness optimization for a monometallic plasmonic structure using the prism-based Kretschmann configuration in angular and spectral interrogation. He-Ne laser with wavelength of 632.8 nm as an optical source, a thin gold layer deposited onto the glass substrate and a BK7 glass prism were applied for this studies. Based on the numerical analysis with variation of metallic layer thickness, angle of incidence and wavelength we will obtain the resonance parameters, such as reflectivity and phase. Experimentally, the SPR spectra of a pure gold sensing surface has been studied. With functionalizing with specific antigen molecules on the surface of the gold layer, this optimized settings can be further used as biosensing purpose for detection of certain analytes.
The Kerr-lens mode-locking (KLM) is known as a suitable method for generation of femtosecond pulses and mode-locked Ti:sapphire laser is now widely used sources of stable, energetic femtosecond pulses. We will present the simulation of KLM in Ti:sapphire laser cavities with a folded-cavity four-mirror by applying the ABCD ray-tracing technique for a Gaussian beam. Simulations will be performed for an asymmetric resonator design. Based on the numerical analysis, we will find the optimum design parameters (slit position, gain cavity spacing, gain medium position) for KLM.
Поликристаллын дифракцын хэмжилтийн үр дүнг мөхлөг тус бүрээр нь ангилж боловсруулахад тавигдах үндсэн хязгаарлалт нь мөхлөгүүдийн пикийн давхцалын зэрэг юм. Иймд мөхлөгүүдийн дифракцын пикийн давхцалын зэрэг мөхлөгийн тоо, туршилтын геометр болон кристалл системийн бүтцийн параметрүүдээс хэрхэн хамаардаг болохыг тооцоолох шаардлагатай.
The Kerr-lens mode-locking (KLM) is known as a suitable method for generation of femtosecond pulses and mode-locked Ti:sapphire laser is now widely used sources of stable, energetic femtosecond pulses. We will present the simulation of KLM in Ti:sapphire laser cavities with a folded-cavity four-mirror by applying the ABCD ray-tracing technique for a Gaussian beam. Simulations will be performed for an asymmetric resonator design. Based on the numerical analysis, we will find the optimum design parameters (slit position, gain cavity spacing, gain medium position) for KLM.
Керр-линз мод синхронизация (КМС) известна как подходящий метод генерации фемтосекундных импульсов, а Ti: сапфировый лазер с синхронизацией мод в настоящее время широко используется в стабильных энергичных фемтосекундных импульсах. Мы представим моделирование КМС в резонаторах Ti: сапфирового лазера со свернутым резонатором, применяя метод трассировки лучей ABCD для гауссовского пучка. Моделирование будет работать для асимметричной конструкции резонатора. Будут обсуждаться синхронизация мод с жесткой апертурой и усиление мод с мягкой апертурой. На основе численного анализа мы найдем оптимальные параметры конструкции (положение щели, расстояние между полостями усиления, положение среды усиления) для КМС. Ключевые слова: Самофокусировка, Керр-линз, Чувствительность смещения.
