Yenista Optics TUNICS T100S-HP, Руководство пользователя

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Using the Auxiliary Inputs and Outputs
48 TUNICS T100S-HP User Manual
Vpp < 2 x R
internal
(I
bias
)
Vpp must be lower than the lowest of these two values.
The TUNICS T100S-HP constantly monitors the average optical output power and
regulates the system bias current to keep the system output power constant. If a DC or
low frequency (below 30 kHz) voltage is applied to the HF Mod input, there is no
modulation on the output power, as the system automatically compensates by adjusting
the bias current to cancel this modulation. However, if the frequency of the signal applied
to the HF Mod input is well above the power control loop cutoff frequency (30 kHz), the
output signal modulation will match that of the input signal, around an average power
determined by the settings of the system. For that reason, you must implement a
modulation frequency above 30 kHz.
8.1.3 Wavelength Modulation
Before Starting
Wavelength Fine
Scanning
The TUNICS T100S-HP has a wavelength fine tuning capability that can be used to adjust
the wavelength very precisely, or to serve the optical frequency.
This function is available via the FSC connector on the rear panel.
When voltage is applied to the FSC connector, the optical frequency shifts
-300 MHz/V for every volt applied.
The maximum input voltage allowed on FSC is ±10 volts.
FSC input also allows wavelength modulation by applying a modulation signal whose
frequency is lower than 450 Hz.
Coherence
Control
When a "noise" signal is directly fed into the FSC input via the 2
nd
+ FSC function to
modulate the optical frequency, this induces an apparent broadening of the laser
linewidth leading to a reduction of the coherence length.
This can be useful to eliminate parasitic interferometers in the user setup. This
modulation is limited to low frequency (DC to 450 Hz typ.). When this function is active,
the LED on the FSC key is blinking.
IMPORTANT Before implementing external modulation via FSC input connector,
make sure the system’s active cavity control is disabled (see section
Disabling/Enabling Active Cavity Control, p. 34 ).