Table 3.5 Automated L-I-V Mode Gpib Commands - ILX Lightwave LDX-36000 Series User Manual

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C H A P T E R
steps is entered via a GPIB command. Data for photodiode current, laser current
setpoint, and laser forward voltage are saved to on-board memory for each laser
current step. This data can be downloaded from the instrument using a GPIB
command. The data is erased after data retrieval.
The mode is intended for single emitter lasers with a forward voltage under 3V.
During execution of L-I-V mode, the instrument sets the power supply voltage to
3V in CW mode and 4.5V in QCW mode and maintains it during the sweep.
Counter to normal instrument operation, the power supply voltage is not
monitored during the sweep. This reduces sweep time.
Caution must be used in setting the delay time. Delays between steps that are too
short may cause inaccuracies in the L-I-V data as the current (or UUT) may not
have settled when the measurements are executed, especially in QCW-Pulse
mode. Some experimentation and comparison with slower L-I-Vs may be
necessary for best results.
The GPIB commands required for this instrument mode are listed below as well as
summarized in Table 5.1 and indivually defined later in Chapter 5. Values for laser
current setpoint start, stop and step size and delay must be defined through the
appropriate GPIB commands before starting the L-I-V sweep. To initiate the L-I-V
sweep, the command "LAS:LIV:OUTPUT ON" must be sent to the instrument.
When the L-I-V mode is activated, the front panel Display 1 will read L-I-U during
the sweep. After the laser current setpoint stop value is reached, the instrument
display will revert back to the original display indicating the sweep is complete.
Once the sweep is complete, the "LAS:LIV:GETMEAS: command can be sent to
retrieve the sweep data. The order of the data is photodiode current in
microamps, laser current setpoint in amps, and laser forward voltage in volts.

Table 3.5 Automated L-I-V Mode GPIB Commands

Name
LASer:LIV:OUTPUT
LASer:LIV:GETMEAS?
LAS:LIV:SET
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 LDX-36000 Series
O P E R A T I O N
Front Panel Operation
Parameters Function
1 Enables or disables the L-I-V instrument mode. The
instrument will step the setpoint current from the start
value to the stop value at increments defined by the
step value.
NONE Returns the LIV data from memory, in a group of 25
data points. For each step, photodiode current, laser
current setpoint, and laser forward voltage values are
saved to memory.
4 Specifies the start current, stop current, step current,
and delay time between steps.