INTUN Tunable Laser
12372-D02, 12/15/2007
Page 26
www.thorlabs.com
Figure 17: Wavelength tuning signal verse laser wavelength
Note that a differential input stage is used, and thus both +WAVELENGTH_TUNING and –
WAVELENGTH_TUNING must be connected.
In order to achieve the 1 pm wavelength resolution, a high-quality, noise-free voltage should be applied
to the +WAVELENGTH_TUNING terminal. The following example illustrates this critical issue:
If we assume that a 110 nm tuning range (110,000 pm) is associated with a 20 V control voltage (peak-
to-peak), the corresponding voltage step is
20 V/110,000 pm
≈
180 µV/pm,
and the D/A converter resolution is better than
log
2
(110,000) > 16.7 bits.
Hence, we recommend using a D/A converter with an 18-bit minimum capacity
Analog Control: OPTICAL_POWER
Provided that the _OPTICAL_POWER_ENABLE signal is set to TRUE – LOW, the optical power can
be set and changed by applying a voltage to +OPTICAL_POWER and –OPTICAL_POWER as
specified in the table and chart below.
OPTICAL_POWER Voltage
Desired Power
Voltage Settings
Optical power off corresponds to –1 V
-OPTICAL_POWER set to 0 V
+OPTICAL_POWER set to -1 V
Lowest optical power corresponds to 0 V
-OPTICAL_POWER set to 0 V
+OPTICAL_POWER set to 0 V
Maximum optical power corresponds to +10 V
-OPTICAL_POWER set to 0 V
+OPTICAL_POWER set to +10 V
λ
1 and
λ
2 correspond to the
shortest and the longest
wavelengths, respectively
(see the technical
specifications for
numerical values).
