ألياف بصرية

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Questions and Answers

ما هو النوع الرئيسي لنظام الاتصالات الذي يعمل على الترددات الضوئية؟

نظام الاتصالات اللاسلكية

نظام الاتصالات الضوئية (correct)

نظام الاتصالات السلكية

نظام تشتيت الصوت

ما هي قيمة طول الموجات المستخدمة في أنظمة الاتصالات الضوئية؟

nanometers ( nm )

ما هي الفئات الرئيسية للإشارات الضوئية بـ حسب طول موجاتها؟

الأشعة فوق البنفسجية

كل ما سبق (correct)

الأشعة تحت الحمراء

الضوء المرئي

يشمل الضوء المرئي مجموعة من الألوان الرئيسية تُعرف بـ ______ ؟

ألوان الطيف Signup and view all the answers

ما هي مزايا الالياف البصرية كمُكوِّنات أساسية لأنظمة الاتصالات؟

سعة الإرسال العالية, مناعة ضد التداخل الكهرومغناطيسي, الفقد القليل, صغر الحجم و الوزن, السرية العالية, مرونة عالية, درجة عالية من الأمان, عمر افتراضي أطول, سهولة في توسعة إمكانيات النظام, نوعية اتصال عالية, قلة تكاليف التركيب والتشغيل Signup and view all the answers

ما هو مبدأ عمل الالياف البصرية؟

الانعكاس الكلي الداخلي Signup and view all the answers

تُصنعُ الألياف البصرية من مادة موصلة للتيار الكهربائي.

False Signup and view all the answers

تُعدّ عمر الليف البصري من محددات أهمية استخدامها في أنظمة الاتصالات.

True Signup and view all the answers

ما هو النوع الأساسي لـ الالياف البصرية حسب معامل الانكسار للـ لب الليف؟

كِلَا الأنواع سابقة الذكر Signup and view all the answers

ما هو النوع الأساسي لـ الالياف البصرية حسب عدد الأنماط المنتشرة ضمن الليف؟

كِلَا الأنواع سابقة الذكر Signup and view all the answers

يمكن استخدام الليف العتبي في نقل البيانات على مسافات طويلة.

False Signup and view all the answers

ما هو النوع الأساسي لـ الالياف البصرية حسب المادة المُستخدمة في تصنيع الليف؟

الليف الزجاجي, الليف البلاستيكي Signup and view all the answers

Study Notes

Optical Fibers

Optical communication systems use optical fibers for high-frequency transmission in the optical frequency range.
Optical wavelengths are extremely short, in the nanometer range.
Optical frequencies range from approximately 10¹² Hz to 10¹⁵ Hz; wavelengths are used to express optical signals instead of frequencies.
Optical frequencies are categorized into:
- Visible light (380 nm to 800 nm)
- Infrared (longer wavelengths than 800 nm)
- Ultraviolet (shorter wavelengths than 380 nm)

Colors of Visible Light

Visible light consists of several primary colors, forming the visible spectrum.
A table provides the primary colors, corresponding frequencies, and wavelengths.
- Example: Red has a wavelength around 750nm and a frequency around 4x10¹⁴ Hz.

Advantages of Optical Fibers

Optical fibers are made of insulating materials (glass or plastic), making them immune to electromagnetic fields.
The transmitted signal is optical, offering several advantages:
- High transmission capacity: Optical systems have a significantly higher transmission capacity than other systems due to higher frequencies.
- Immunity to electromagnetic interference: Optical fibers are not affected by electromagnetic fields, making them suitable for high electromagnetic field environments.
- Low loss: Optical fibers have remarkably low signal loss, enabling transmission over long distances.
- Small size and weight: Compared to copper cables, optical fibers are much smaller and lighter, increasing usability in various applications.
- Higher security: The optical signal is confined to the fiber, making it extremely difficult to tap or intercept.
- High flexibility: Optical fibers can be easily stored, transported and installed due to their high tensile strength in their flexibility.
- Longer lifespan: Optical fibers have a significantly longer lifespan (20-30 years) than copper cables (12-15 years).

Ease of Expansion System Capability

System capacity is easily increased by replacing components.

High Quality Transmission

Optical communication offers superior quality with low loss, superior electromagnetic interference immunity, and minimal interference between adjacent lines—compared to other telecommunication systems.
Optical systems have a much lower bit error rate (BER) compared to microwave or copper wire systems (e.g., BER ≤ 10^-9 vs. 10^-10)

Optical Fiber Disadvantages

Higher cost of components compared to electrical systems.
High cost of transmitters and receivers.
Expensive installation process that requires specialized equipment and skilled labor.

Fiber Optic Applications

Long-distance telecommunications
Local telephone networks
Closed-circuit television (CCTV)
Internet and data communications
Military communications

Fundamentals of Optical Fiber

Optical fibers are the primary component of optical communication systems, using light as the information carrier (carrier wave).
Three aspects explain light's behavior:
- Wave theory: Light as an electromagnetic wave
- Geometric optics: Light as a ray
- Quantum theory: Light as photons

Light Ray Theory

Light travels as a beam with a specific velocity, dependent on the medium.
Refractive index (n) quantifies a medium's hindering effect on light propagation, calculated as the ratio between the speed of light in a vacuum (c) and the speed of light in the medium (v).
The formula for light velocity in a different medium from a vacuum is c = c/n.

Snell's Law

Snell's law relates incident, reflected, and refracted rays to the associated angles.

Critical Angle (Total Internal Reflection)

Critical angle is the incident angle required to cause a refracted angle of 90 degrees when light propagates from a higher refractive index medium to a lower index medium.
It results in complete internal reflection, wherein the light is reflected back into the fiber, if the angle of incident is greater than critical angle
The main condition for total internal reflection is that the light must be propagating from a medium with a higher index to a medium with a lower index.

Fiber Structure

Optical fiber consists of a core and cladding, coated by a protective layer.
The core has a higher refractive index, and the cladding has a lower refractive index
The protective layers safeguard the fiber from environmental factors.

Normalized Frequency (V)

The V-number is a crucial parameter for analyzing propagation modes, calculated by =2πan/λ.

Optical Fiber Types

Optical fibers are classified according to refractive index variation and the number of propagating modes.
Types include step-index and graded-index fibers, depending on the refractive index profiles within the core.
Multimode fibers allow multiple modes of propagation whereas, Single-mode fibers allow only one propagating mode.

Plastic Optical Fibers (POF)

POF are made entirely of plastic.
They are characterized by:
- Low cost
- Larger size
- High NA
- Flexibility

Practical Characteristics of Optical Fibers

Fiber characteristics are summarized into groups based on core diameter, jacket diameter and other additional specifications.

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Description

تستعرض هذه المسابقة أنظمة الاتصالات البصرية وأبعادها المختلفة. تشمل المواضيع ألوان الضوء المرئي، واستخدام الألياف البصرية لنقل إشارات ضوئية في نطاق الترددات العالي. تعرف على الخصائص والفوائد العديدة للألياف البصرية.