5. Electromagnetics and Photonics

Optical Devices — Quiz

Test your understanding of optical devices with 5 practice questions.

Practice Questions

Question 1

A laser diode has threshold current $I_{th}=20\,\mathrm{mA}$ and slope efficiency $S=0.5\,\mathrm{W/A}$. If it is biased at $I=50\,\mathrm{mA}$, what is its optical output power $P_{out}$?

Question 2

In a PIN photodiode with junction capacitance $C=3\,\mathrm{pF}$ and a load resistor $R=1\,\mathrm{k\Omega}$, what is the approximate 3-dB electrical bandwidth $f_{3\mathrm{dB}}$?

Question 3

An optical source operating at wavelength $\lambda=1310\,\mathrm{nm}$ has a spectral width $\Delta\lambda=0.1\,\mathrm{nm}$. What is its coherence length $L_{coh}$?

Question 4

A fiber Bragg grating with effective refractive index $n_{\mathrm{eff}}=1.46$ and grating period $\Lambda=530\,\mathrm{nm}$ reflects at which Bragg wavelength $\lambda_{B}$?

Question 5

Why is population inversion easier to achieve in a four-level laser system compared to a three-level system?