Using the Auxiliary Inputs and Outputs
48
T100S-HP User Guide
If the voltage applied to the
HF Mod
input is an AC signal with no DC component, and
whose peak-to-peak amplitude is
V
pp
, the above condition becomes:
Vpp < 2 x R
internal
(I
max
-I
bias
)
Vpp < 2 x R
internal
(I
bias
)
Vpp
must be lower than the lowest of these two values.
The 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 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
Enabling Active Cavity Control, p. 35
).
Summary of Contents for T100S-HP Essential
Page 1: ...www EXFO com T100S HP High Power Tunable Laser User Guide T100SHP_UM_6 06v1 2...
Page 2: ......
Page 10: ...Important Safety Information for Your Product 10 T100S HP User Guide...
Page 20: ...Product Presentation 20 T100S HP User Guide...
Page 24: ...Installing and Connecting the Product 24 T100S HP User Guide...
Page 42: ...Enabling Active Wavelength Monitoring 42 T100S HP User Guide...
Page 50: ...Using the Auxiliary Inputs and Outputs 50 T100S HP User Guide...
Page 54: ...Verifying Performances 54 T100S HP User Guide...
Page 58: ...Performing Basic Maintenance Operations 58 T100S HP User Guide...
Page 64: ...List of Tables 64 T100S HP User Guide...
Page 66: ...List of Figures 66 T100S HP User Guide...
Page 70: ...Index 70 T100S HP User Guide...