A link upgrade from multi-mode to single-mode fibre can be achieved by replacing the optical components on the circuit board.
The PLD-1315 transmitter consists of a 1300nm Edge Emitting LED (ELED), which couples its optical output into single-mode optical fibre. While LASER based emitters require optical feedback, the drive circuit for the ELED can be the same circuitry that is used with multi-mode LED based components.
The PLD-23XX receiver consists of a 75µm diameter InGaAs PIN photodiode and a trans-impedance amplifier with the option of AGC. The PIN photodiode is optimised for high response in the 1300nm wavelength region and is matched with a low-noise TIA. The optical signals are detected by the PIN and converted to an analogue voltage output with a very low input noise current contribution. When the average incident optical power is high, the AGC feature decreases the light to voltage conversion factor. The receiver has a sensitivity of –36dBm at 100MHz and, with filtering, a minimum overload value of 0dBm.