QFor ADN2830, I would like to get the detailed transfer functions between IMPD
and IBIAS. I found there was only the simple description stated in the
datasheet. Would you pls give the exact transfer function between them?
AMPD is one monitoring photo-detector diode. It is bounded in a TOSA package,
side by side of the Laser Diode.
MPD will sense the optical power sent by the laser diode. The transfer ratio of
optical light to photo-current
Is called MPD responsivity. If MPD is a PIN diode, the responsivity could be
about 0.5 ~ 0.9 A/W.
Laser diode will generate an optical power driven by the bias current. The
efficiency calls slope efficiency.
If the laser is made of DFB, the slope efficiency is about 0.001 ~ 0.01 W/A or
Between the laser and the MPD, the optical coupling factor is their location,
orientation dependent. In most case,
This factor is a fixed data and can be calibrated out.
So, a MPD current could be Impd = Pav x Re; where Pav is the optical average
power, Re is the MPD responsivity.
Pav = h x (IBIAS - Ith), h is the laser slope efficiency, IBIAS is the laser
bias current, and the Ith is the laser diode threshold current.