1. What is Polarization Extinction Ratio (PER)?

Definition: PER measures the quality of polarization in an optical system by comparing maximum and minimum power states.

Purpose: It quantifies how well a system maintains polarization purity, important in fiber optics, lasers, and optical communications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( PER \) — Polarization extinction ratio (dB)
• \( P_{max} \) — Maximum power in the desired polarization (W)
• \( P_{min} \) — Minimum power in the orthogonal polarization (W)

Explanation: The ratio of maximum to minimum power is converted to decibels (dB) using a logarithmic scale.

3. Importance of PER Measurement

Details: High PER values indicate better polarization purity, crucial for applications like fiber optic communications, quantum optics, and polarization-sensitive measurements.

4. Using the Calculator

Tips: Enter both power values in watts (W). P_max must be greater than P_min and both must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What is a good PER value?
A: Typical values range from 20 dB (good) to 40 dB (excellent) depending on the application.

Q2: How is PER different from extinction ratio?
A: PER specifically refers to polarization states, while extinction ratio can refer to other binary states in optical systems.

Q3: What affects PER in optical systems?
A: Factors include fiber bending, connectors, splices, and component quality.

Q4: Can PER be negative?
A: No, since P_max should always be greater than P_min, the ratio is always >1, making PER positive.

Q5: How do I measure P_max and P_min?
A: Use a polarizer to align with the desired polarization for P_max, then rotate 90° for P_min.