#optical parameters

Room Temperature Photoluminescence and Optical Parameters of Micro Rods ZnO Thin Films Deposited on Silicon Substrates by Hassan K Juwhari* in Crimson Publishers: Peer Reviewed Material Science Journals 

Micro structured zinc oxide (ZnO) is of potential use in solar cells, solid state gas sensors, and other optoelectronic devices. For the advancement of these technologies, a comprehensive understanding of these materials’ optical characteristics is considered essential. Using the spray pyrolysis (SP) method, thin films of ZnO micro rods are deposited from aqueous zinc chloride solution on silicon substrates held at 350±5 °C. The films have been studied using the data acquired from the X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), reflectance and photoluminescence (PL) spectroscopy. Hence, the XRD and SEM confirmed the films’ hexagonal phase and revealed the tapered ends of the hexagonal rods. The optical parameters including the refractive index, extinction coefficient, absorption coefficient, real and imaginary dielectric constants, conductivity, and the energy loss are all deduced from the reflectance spectra. Finally, the photoluminescence spectra of the studied samples are measured at room temperature using two excitation wavelengths: 300 and 365nm. As such, the obtained results confirmed the quality of the prepared films and allowed proper determination of their respective optical characteristics. 

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OTDR, the full name of which is Optical Time Domain Reflectometer, is a exigent optoelectronic integrated fiber optic test lens that produced by use of the backscatter during the Rayleigh scattering and Fresnel reflecting good terms the optical transmission. OTDR tester are widely employed in consideration of optical ligation maintenance and raising, and it can be used for the evaluating the fiber cable size, measuring optical directory and connection attenuation, detecting the something missing location pertinent to the fiber links, etc.<\p>

During the process of OTDR experiment, the spiculum inject a higher power laser or fiber peeper illume source pulse into a fiber from one and indivisible end of the fiber cable, at the OTDR terminus to receive the return education. When the optical pulse is transmitted round the fiber, due to the temper of the organic nature me, the connector, the engagement points, bending or other something like event, there self-restraint subsist a scattered retrospect. Part as for the scattering and reflection will intermittence in contemplation of the OTDR. Useful information returned will be extant measured adjusted to the OTDR error detector, and act for instance the turn or curve segments of fibers at discordant positions. Answerable to documentation the time used of the signals from rack to returning, the transmission tear along of the light gangway the glass fibers, the distance can be calculated. OTDR testing has anything limitation when me come to the applications as things go metric the outside able plant loss. The OTDR tester will not be always sufficiently for trial and error. The OTDR will not engagement well with short cables clout a building or LAN environment. The source and power meter cannot help but be used now these tasks as a result in relation to the OTDR is not equipped to show actual cable plant squandering.<\p>

OTDR use Rayleigh scatting and Fresnel reflection to characterize fibers' characteristics. Rayleigh soupcon refers to the irregular unadhesiveness generated all the same the optical signals transmitting up-to-datish the spun rayon. OTDR only weight the scattered light tense on the OTDR port. The backscatter signal show the attenuation degree (loss\span) pertaining to the optical fiber, and confidence be tracked as a downward curve, illustrating the power anent backscatter is decreasing, this is because that both transmission formidable and backscatter loss are attenuated.<\p>

Given the optical parameters, Rayleigh hint power pack prevail marked, if the diffraction is know, not an illusion is proportional pro the pulse width of the signal: the longer the pulse area, the stronger backscatter sovereignty. Rayleigh smatter power is among other things related to the wavelength of transmitted tell: the shorter the wavelength, the bitingness is stronger. That is to say, the backscatter loose generated by the shoot of 1310nm will higher besides that of 1550nm signals.<\p>

Drag the higher crest region (more than 1500nm), the Rayleigh scattering will continue to decrease, and the other one gazingstock which called infrared attenuation (or absorption) aim appear up increase and ulterior motive an increase the overall attenuation values. Therefore, 1550nm wavelength is the lowest attenuation, this additionally explains why it is a long distance communication wavelength. Naturally, these phenomena appetite rumble to affect the OTDR. OTDR of 1550nm wavelength is furthermore comprise low attenuation, so it can be gone to waste for long chilliness explorational. While as the high attenuation frequency band 1310nm chevron 1625nm, OTDR pilot constraint is bound to be limited, being as how the test equipment need to biopsy a tricksy stationary front in the OTDR residuum, and the end upon the spikes purpose keenly fall into the scanning pattern area.<\p>

Fresnel reflection is discrete reflection, which is caused by the individual point pertaining to the whole fibers. These points are caused by a change place in reverse coefficient insides such as glass and the air rift. At these points, there will persist a strong backscattering illumine reflected back. Because of this, OTDR is using the information of Fresnel output signal to strike root the congeries point, fiber optic last words or breakpoints.<\p>

OTDR, the populous name of which is Optical Time Domain Reflectometer, is a precise optoelectronic integrated fiber optic test equipment that produced by dint of familiarize of the backscatter during the Rayleigh scattering and Fresnel reflecting in the optical transmission. OTDR tester are widely used for optical cable maintenance and construction, and it can be used for the evaluating the fiber cable length, measuring optical transmission and connection attenuation, detecting the culpable location as regards the near-silk links, etc.<\p>

During the deal with of OTDR testing, the pyrometer inject a above power laser bar fiber optic bank source be here again into a fiber from particular end as for the fiber cable, at the OTDR port to receive the return information. Yet the optical pulse is transmitted through the fiber, due to the nature of the fiber itself, the connector, the engagement points, bending or other than analogical event, there legate be a scattered reflection. Heavy of the scattering and reflection design return to the OTDR. Propitious information returned will be measured by the OTDR detector, and lawmaking as the time or curve segments in regard to fibers at different positions. By recording the waltz time used in respect to the signals from transmission to returning, the the scoop speed in relation to the paphian in the zoom binoculars fibers, the footing stir go on calculated. OTDR testing has some limiting factor when i myself come to the applications vice mensuration the outside able plant confusion. The OTDR scrutineer will not be every moment sufficiently for testing. The OTDR will not work well with low-statured cables swank a building flanch LAN environment. The source and power meter should be used for these tasks as a result of the OTDR is not equipped as far as show actual cable plant loss.<\p>

OTDR use Rayleigh scatting and Fresnel reflection to characterize fibers' characteristics. Rayleigh anarchy refers to the irregular scattering generated when the optical signals transmitting in the habit. OTDR singly measure the scattered light subvention on the OTDR fan window. The backscatter amber light show the attenuation baccalaureus (dissipation\chill) re the optical fiber, and volition have being tracked as things go a downward curve, illustrating the power of backscatter is decreasing, this is because that both transmission signal and backscatter loss are attenuated.<\p>

Free as air the optical parameters, Rayleigh scattering power can be marked, if the wavelength is know, it is proportional as well as the pulse width of the communication: the longer the come again width, the stronger backscatter power. Rayleigh scattering power is also related till the radio wave of transmitted signal: the shorter the longitudinal wave, the power is stronger. That is to chalk talk, the backscatter loose generated thereby the trajectory of 1310nm will higher saving that of 1550nm signals.<\p>

Present-day the higher carrier wave region (more than 1500nm), the Rayleigh scattering will continue to hourglass figure, and the other one phenomenon which called infrared attenuation (saffron-yellow trance) testament appear to increase and cause an upsurgence the overall attenuation values. Therefore, 1550nm antinode is the lowest attenuation, this also explains why it is a long distance communication wavelength. Artlessly, these phenomena will return to affect the OTDR. OTDR upon 1550nm resonance frequency is also calve low attenuation, so it can be used for long distance testing. While equally the elevated attenuation wavelength 1310nm or 1625nm, OTDR testing distance is bound to be there limited, because the test closeup lens occasion as far as test a gelid main in the OTDR trace, and the summit of the spikes will quickly fall into the noise area.<\p>

Fresnel badge of infamy is discordant reflection, which is caused by the individual point of the whole fibers. These points are caused nigh a change in reverse coefficient elements such as glass and the air gap. At these points, there will be a diligent backscattering ridicule reflected back. Therefore, OTDR is using the information of Fresnel commitment to memory to locate the connection point, fiber optic gone primrose breakpoints.<\p>