Papers by Morteza Mahmoodzadeh
Optics and Photonics Society of Iran, 2018
Notch filter is an optical instrument that its performance is based on the Interference phenomeno... more Notch filter is an optical instrument that its performance is based on the Interference phenomenon. The Notch filters, (reflective filter) act is that it reflects a wavelength range around the central wavelength and completely passes the rest of the wavelengths. One of the methods for producing these types of fillers is to use a pair of alternating quarter-wavelengths thin films in the form of (aHbL). Although this design has problems like high-level reflections in the transmission region. In this research it has been tried to study and simulate the structures (aHbL), with using different materials and thicknesses to increase the central reflection, also reduce the bandwidth of the reflection around the central wavelength has been reduced.
Optics and Photonics Society of Iran, 2019
Optical anti reflection thin-film are widely used in the photonic industry, these layers are used... more Optical anti reflection thin-film are widely used in the photonic industry, these layers are used in optical window, lenses and other optical elements. They are also used in beam expander and other optical elements that used to focus laser beam. But the rise in laser energy causes the damage of these types of coatings. In this paper, we have tried to find an optimal method using three different methods of cleaning, which would increase the threshold of laser damage to these coatings.
Optics and Photonics Society of Iran, 2019
کی تسا هتفرگ رارق یزاس هیبش و یسررب دروم ینایم خرسورف فیط رد ینفارگ راون زا هیارآ . هدهاشم جوم لو... more کی تسا هتفرگ رارق یزاس هیبش و یسررب دروم ینایم خرسورف فیط رد ینفارگ راون زا هیارآ . هدهاشم جوم لوط تارییغت هک دش شیلاآ تظلغ کدنا تارییغت اب دیدشت راون تسد لباق ینفارگ یاه تسا یبای . یم ناشن یزاس هیبش نیب یمرف یژرنا لیدعت اب هک دهد 2 / 0 ات تلو نورتکلا 22 / 0 شیارآ یارب تلو نورتکلا راون ینفارگ یاه 4 یم هیلا جوم لوط تفیش هب دناوت 44 / 0 هسیاقم رد رتمورکیم اب 52 / 0 دسرب هیلا کت تلاح یارب رتمورکیم . هاگتسد یارب ار هار اهزادنا مشچ نیا یاهدربراک یارب نفارگ رب ینتبم عیرس قوف یاه رهارت و زمرق نودام یم مهارف زت دزاس . هژاو دیلک ،ینایم خرسورف فیط راون دیدشت جوم لوط ،ینفارگ یاه
Optics and Photonics Society of Iran, 2019
Nowadays, there has been a lot of development in the production of chrip mirrors. These mirrors a... more Nowadays, there has been a lot of development in the production of chrip mirrors. These mirrors are being used to create ultrashort femtosecond pulses for high power lasers. In this study, we setup a Michelson interferometer to record white light interferons. Finally, we caculate the group delay dispersions using the wavelet transform method, which are in good agreement with standard data.
Optics and Photonics Society of Iran, Mar 15, 2015
In this paper, the impact of deposition conditions such as substrate temperature, rate of deposit... more In this paper, the impact of deposition conditions such as substrate temperature, rate of deposition and residual oxygen partial pressure were investigated on the optical properties of yttria thin films. The deposition was made by reactive electron beam evaporation in vacuum of 10-6 orders and measuring reflectance maximum was done by spectroscopy in 400-800 nm region. The results showed that partial pressure of oxygen had the strongest effect on optical properties. Therefore, using this condition, we managed to make thin films structures with different optical properties and the same material.
Optics and Photonics Society of Iran, Mar 15, 2015
Materials Science in Semiconductor Processing, 2012
Tin oxide (SnO 2) thin films were deposited on glass substrates by thermal evaporation at differe... more Tin oxide (SnO 2) thin films were deposited on glass substrates by thermal evaporation at different substrate temperatures. Increasing substrate temperature (T s) from 250 to 450 1C reduced resistivity of SnO 2 thin films from 18 Â 10 À 4 to 4 Â 10 À 4 O cm. Further increase of temperature up to 550 1C had no effect on the resistivity. For films prepared at 450 1C, high transparency (91.5%) over the visible wavelength region of spectrum was obtained. Refractive index and porosity of the layers were also calculated. A direct band gap at different substrate temperatures is in the range of 3.55 À 3.77 eV. X-ray diffraction (XRD) results suggested that all films were amorphous in structure at lower substrate temperatures, while crystalline SnO 2 films were obtained at higher temperatures. Scanning electron microscopy images showed that the grain size and crystallinity of films depend on the substrate temperature. SnO 2 films prepared at 550 1C have a very smooth surface with an RMS roughness of 0.38 nm.
Journal of Luminescence, 2012
Transparent conductive WO 3 /Ag/MoO 3 (WAM) multilayer electrodes were fabricated by thermal evap... more Transparent conductive WO 3 /Ag/MoO 3 (WAM) multilayer electrodes were fabricated by thermal evaporation and the effects of Ag layer thickness on the optoelectronic and structural properties of multilayer electrode as anode in organic light emitting diodes (OLEDs) were investigated using different analytical methods. For Ag layers with thickness varying between 5 and 20 nm, the best WAM performances, high optical transmittance (81.7%, at around 550 nm), and low electrical sheet resistance (9.75 O/cm 2) were obtained for 15 nm thickness. Also, the WAM structure with 15 nm of Ag layer thickness has a very smooth surface with an RMS roughness of 0.37 nm, which is suitable for use as transparent conductive anode in OLEDs. The current density À voltage À luminance (J À V À L) characteristics measurement shows that the current density of WAM/PEDOT:PSS/TPD/Alq 3 /LiF/Al organic diode increases with the increase in thickness of Ag and WO 3 /Ag (15 nm)/MoO 3 device exhibits a higher luminance intensity at lower voltage than ITO/PEDOT:PSS/TPD/Alq 3 /LiF/Al control device. Furthermore, this device shows the highest power efficiency (0.31 lm/W) and current efficiency (1.2 cd/A) at the current density of 20 mA/cm 2 , which is improved 58% and 41% compared with those of the ITO-based device, respectively. The lifetime of the WO 3 /Ag (15 nm)/MoO 3 device was measured to be 50 h at an initial luminance of 50 cd/m 2 , which is five times longer than 10 h for ITO-based device.
Optics and Photonics Society of Iran, Mar 15, 2015
In this paper, a computer code for simulation and optimization of thin film optical systems inclu... more In this paper, a computer code for simulation and optimization of thin film optical systems including absorbing layers is presented. Transmittance, reflectance and absorption are calculated in this code using matrix method for S and P polarizations. Then these characteristics are optimized using the layers with thickness variables with Monte Carlo method.
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Papers by Morteza Mahmoodzadeh