THORLABS PICO D, User Manual

Page: 22 / 48

22
2.5.3.2.1 Definition of the control signals
The table below lists the available control signals. The logical states are defined in
paragraph 2.5.3.1. Carefully read paragraph 2.5.3.1 (Definition of the logical states)
before connecting PICO D. The full pin configuration of the PICO D power and signal
connectors are shown in Figure 2–15.
Table 2-4 The digital control signals
Name Short description
_WAVELENGTH_TUNING_ENABLE
When enabled, PICO D is ready to accept and respond to
wavelength tuning input
_COHERENCE_CONTROL_ENABLE
When enabled, a dither signal is added to the wavelength
control signal in order to minimize influence of standing
waves.
_OPTICAL_POWER_ENABLE
When enabled, optical power is emitted from the outout
fiber.
_CONSTANT_CURRENT_ENABLE When enabled, the unit is operated at constant laser current
_MODE_HOP_ADJUST_ENABLE
When enabled, the cavity temperature can be adjusted to
compensate for mode hops.
Figure 2–10 Digital input circuitry
2.5.3.2.2 Digital control: _WAVELENGTH_TUNING_ENABLE
When digital control signal _WAVELENGTH_TUNING_ENABLE is set to LOW (0 V)
the unit is ready to accept and respond to wavelength tuning (using analog control
WAVELENGTH_TUNING see 2.5.4.1).
When _WAVELENGTH_TUNING_ENABLE is set to HIGH (5 V) the wavelength can
NOT be tuned (changed), the wavelength is set to mid value (that corresponds to 0
V on the control analog WAVELENGTH_TUNING) irrespective of analog WAVE-
LENGTH_TUNING control voltage (see 2.5.4.1 ).
2.5.3.2.3 Digital control: _COHERENCE_CONTROL_ENABLE
When digital control signal _COHERENCE_CONTROL_ENABLE is set to LOW (0
V) the effective optical line-width of the output optical light is broadened.
2.5.3.2.4 Digital control: _OPTICAL_POWER_ENABLE
When digital control signal _OPTICAL_POWER_ENABLE is set to LOW (0 V) the
output optical power from the unit is set according to the voltage of the analog opti-
cal power input.