Question

A hyperbolic secant pulses (sech(t)) at 1500 nm with 100 mW peak power enters a fiber with 0 dispersion and n2​=4×10−20 m2/W. Amount of loss in fiber is 4% per kilometers and the mode diameter is 8μm. Calculate the nonlinear phase shift in 40 km

Answer 1

To calculate the nonlinear phase shift (φNL) in a fiber, use the given formula and provided values for the nonlinear parameter (γ), peak power (P), and effective length (Leff) of the fiber over 40 km, taking into account the losses.

Step-by-step explanation:

To calculate the nonlinear phase shift in the fiber, we use the following formula for the nonlinear phase shift φNL:

φNL = γ * P * L

Where:

• γ is the nonlinear parameter of the fiber
• P is the peak power of the pulse
• L is the effective length of the fiber considering losses

The nonlinear parameter γ is given by:

γ = (2 * π * n2) / (λ * Aeff)

With λ representing the wavelength of the pulse and Aeff as the effective mode area of the fiber.

The effective length Leff considering the loss α (in dB/km) can be approximated as:

Leff = (1 - e-α * L) / α

Since these values were provided in the question (n2, λ, P, α, mode diameter), the student can now plug these values into the formula to calculate the nonlinear phase shift after considering the fiber's losses over 40 km.