Configuring External Photodiode Power Measurements; Adjustable Photodiode Bias; Liv Sweep Mode - ILX Lightwave LDX-36000 Series User Manual

Configuring External Photodiode Power Measurements

If a photodiode is connected to the instrument, the instrument will measure optical
power in terms of either photocurrent in µA or optical power in Watts. Pressing
the DISPLAY 1 P/PPD button until the Display 1 enunciator W PD is illuminated
allows for measurement of optical power via an external photodiode.
The photodiode responsivity, CAL PD, is used to convert between photodiode
current and optical power of the laser diode. To enter the CAL PD parameter,
select CAL PD with the SELECT push button by toggling down past CAL P. The
indicator becomes lit when CAL PD is selected and DISPLAY 1 indicates the
responsivity parameter in mA/W (not annunciated). Next, press the Parameter
Set button and rotate the Adjust knob to change responsivity values with units of
mA/W.
To calculate the responsivity:
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2
3
4

Adjustable Photodiode Bias

An adjustable reverse bias of 0 - 15 VDC is provided for best linear response of
the photodiode. To set the photodiode bias, press the Parameter Select button
(Figure 3.7) until the PD BIAS LED is illuminated. The bias level is indicated on
Display 1 in Volts. Next, press the Parameter Set button and rotate the Adjust
knob to change the bias level.

LIV Sweep Mode

An automated L-I-V mode is available on some LDX-36000 Series instruments
and is accessible through GPIB commands only.
LDX-36010-12
LDX-36025-12
LDX-36050-12
In this mode, the instrument automatically executes an L-I-V sweep initialized
from a command in either CW or QCW mode (not HPulse mode). A
programmable laser current start point, stop oint, step size, and delay between
03_10
Note: Display 1 will indicate power in Watts only when the photodiode responsivity value is
nonzero.
Measure (with a calibrated detector) the output power of the device.
Illuminate the detector to be used for power measurement.
Measure the corresponding photodiode current.
Calculate the responsivity by dividing the photodiode current by the optical power noting
the units required are mA/W.
10A/20A
25A/50A
50A/100A 12V output
Front Panel Operation
12V output
12V output
O P E R A T I O N
LDX-36000 Series
3
C H A P T E R
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