The thesis of the master’s student, Aya Riyad Mijbil, / Laser Applications / Physics, was discussed, for her entitled thesis: Offset refractive index sensor for optical fibers.
Where the discussion committee consisted of the professors whose names are listed
1- Prof. Dr. Abd al-Hadi Mutashar Abd / Ph.D. Laser Plasma / Physics / Institute of laser for Postgraduate Studies / University of Baghdad / As a Chair person
2- Asst. Prof. Dr. Zainab Fadel Mahdi / Ph.D. – Laser and Spectra / Physics / Institute of laser for Postgraduate Studies / University of Baghdad / As a Member
3- Asst. Prof. Dr. Ali Abdel-Khaleq Abdel-Hadi / PhD in Advanced Photonics / Optical Sensors and Detectors / Department of Laser Engineering and Optoelectronics / University of Technology / As a Member
4- Asst. Prof. Dr. Hanan Jaafar Taher / PhD_ Laser / Physics Sciences / Institute of laser for Postgraduate Studies / University of Baghdad / As a Member and Supervisor
Where the aim of the study was to manufacture a refractive index sensor based on offset technology, and to study several parameters that affect the sensitivity of the sensor, including:
In this work, a simple all-fiber coreless Mach- Zehnder interferometer sensor based on offset technique has been manufactured and demonstrated for refractive index sensing. Initially, MATLAB program was used to theoretically investigate the effect of coreless fiber length on the number of self-images. The effect of the length, offset (one side, two sides, and the offset shape), diameter of coreless fiber, and the coating with different concentrations of Titanium Oxide Nanoparticles (TiO2), all of which have been experimentally studied as effective variables for improving sensor sensitivity. This sensor is generally constructed by cleaving and splicing Coreless Fiber (CF) between two sections of Single Mode Fibers to create the single mode _ coreless _ single mode (SCS) structure. In order to study the influence of the CF length with offset (fixed offset in one side) on the sensitivity and to choose the best length then different lengths of CF were used to conduct the experiment. The highest sensitivity was found at 6cm length with 90.722nm/RIU with fixed offset in one side (10.498µm). After selecting the appropriate length, the effect of different displacements (offset in one side) has been studied to select the best offset, The highest sensitivity achieved was 106.437nm/RIU at offset of 12.268µm.
 
One of the most important recommendations of the study is that, the offset technique (lateral displacement) is very effective in improving the sensitivity of the sensor.
-The sensitivity of the sensor is affected by the value of the lateral displacement (offset).
-The shape of the offset is an important and effective factor on the sensitivity of the sensor, as two forms of offset have been studied, namely the S and U.
-U is the highest sensitivity of the S-form, as the results showed that the L-form
-It is possible to use several improvements to the sensitivity of the sensor with the offset technique, such as: reducing the diameter of the coreed fiber (where the diameter of the fiber was reduced to 50 microns), and coating the coreed fiber with a nanomaterial
With a diameter of 50 microns, the S-shape of the nanoparticles increases on TiO2\PVA,  where it was observed when coating one layer of the sensor, the sensitivity ranged from 210.214 to 291.691 nm/refractive index units.
-It is possible to use other types of Nano coatings such as gold nanoparticles.
-The manufactured sensor is low cost, easy to manufacture, and suitable for many applications such as medical, industrial, and other applications
The researcher obtained a master’s degree with a grade of “excellence” due to her real efforts in preparing the thesis.

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