Tools

Characteristics of Avalanche Photo Diode (APD).

Procedure

  1. Make the set-up as in the diagram and connect the 1KΩ resistor across VL.
  2. set the bias voltage at 10 V.
  3. Set the power source in CW mode and adjust to get maximum output. Connect the 1m ST-ST patch cord between source and power meter and adjust the power to -18dBm.
  4. Connect the optical fiber cable to the PD module and measure the voltage across RL[1KΩ] and note as VL.
  5. Vary the bias voltage from 10 V in steps of 20 V up to 140 V and note down the corresponding VL.
  6. Calculate IR = VL / (1 x 103 ).
  7. Plot the graph : VBIAS Vs IR.
  8. Repeat steps 4 to 7 for different input powers say -25 dBm, -40 dBm, etc.
  9. Calculate the responsivity from : Rλ = VL /(RL*PS) A/W where PS is the power in Watts.
  10. From the average value of Rλ, calculate the quantum efficiency using: ηC = (Rλhν/e) x 1/100 % where h=6.63 x 10-3 Js; e = 1.6 x 10-19 C; ν = c/λ = 3 x 108/λ

Figure 1: Set up for Characteristics of Avalanche Photo Diode (APD)