Study of nonlinear polarization density as a function of some media characteristics

العناوين الأخرى

دراسة كثافة الاستقطاب اللاخطي بدلالة بعض خصائص الوسط

مقدم أطروحة جامعية

Ali, Abd al-Karim Mahdi Salih

مشرف أطروحة جامعية

al-Kamil, Abd al-Munim Khalil
al-Zahir, Tariq Abd al-Rida

أعضاء اللجنة

al-Birmani, Muhammad Jafar Fadil
al-Nakishli, I. S.
Husayn, Ali A.
Salman, Jamal Wahhab
Majid, Rad Hamid

الجامعة

جامعة بغداد

الكلية

كلية التربية للعلوم الصرفة-ابن الهيثم

القسم الأكاديمي

قسم الفيزياء

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2005

الملخص الإنجليزي

Bloch equations have been used to evaluate the medium nonlinear polarization density behaviour, according to the quantum theory.

The medium has been represented as a two- level system.

In this representation, matrix density formula has been described the two levels coupling, under rotating wave approximation (RWA).

A computer code has been written to solve numerically Bloch equations simultaneously, using Runge-Kutta-Fehlberg method.

A bench mark problem has been used succeffely to check the computer code accuracy; the output results mirror those published.

Our code has been utilized to study the effect of longitudinal relaxation time on the medium nonlinear polarization density behaviour at exact and non-exact resonance cases of wave-matter interactions.

Concerning that, nonlinear polarization density behaviour shows fast build-up at the initial interaction time, and then decay at later time to approch saturation ( minimum values of nonlinear polarization density) at last time.

The decay in the non-exact resonance interaction is larger than that in the exact resonance.

The effect of frequency detuning (Δ) ( it is detuning between the transition frequency Wba and the fundamental wave frequency W0 ) on the nonlinear polarization density behaviour has been studied.

It appers that, the nonlinear polarization density decreases when the interaction becomes far away from exact resonance.

Finally, the effect  (ratio of longitudinal relaxation time to transverse relaxation time), on the response time of the nonlinear medium and how long does the medium obeay the nonlinearity.

It has been observed from the study that at certain limit values of , the response time will increase while increasing .

After these values, the increasing of  will possesse very little effect on the nonlinear response time.

التخصصات الرئيسية

الفيزياء

عدد الصفحات

103

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-755565