THORLABS MX40G Series, Руководство пользователя

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MX40G, MX70G Series of E-O Converters Chapter 4: Operating Instructions
Page 14 TTN116413-D02
4.4 Bias Settings Page
The Bias Settings page is accessed by tapping the center bias monitors pane on the Home page. When the MZM Bias control
is first turned on, the converter performs a calibration routine to determine the approximate bias voltages required for the various
MZM operating points. This allows the instrument to quickly and effectively switch between bias modes. The user may perform
this calibration anytime by pressing the Reset Auto Bias button on the right side of the Bias Settings page. This button is not
available if the Bias is off or in Manual mode.
Figure 20 Bias Settings Home Screen
The Bias Settings page contains the settings for controlling the modulator bias and operating modes. There are four modes for
MZM bias control: 1) Quadrature, 2) Peak, 3) Null, and 4) Manual. The screen shot below is an example of the information
presented and the controls available when the Mode field is selected while the controller is operating in Quadrature mode. The
blue buttons enable switching between modes.
Figure 21 Bias Settings Screen when Mode Field is Selected while Quadrature Mode is Enabled
Active control of the MZM bias point is essential, as the modulator is temperature sensitive and will drift over time. The
Quadrature, Peak, and Null modes use a dither tone as part of a lock-in control scheme to keep the MZM bias stable. The dither
tone allows the control algorithm to track the drifting, but at the cost of decreased signal-to-noise ratio (SNR) due to the injection
of a single frequency tone into the MZM bias.
Tap to turn Bias On/Off.
Tap to Reset Modulator Bias.
New set points will be stored.
Tap to select Peak Mode.
Tap to select Quadrature Mode.
Tap to select Null Mode.
Tap to select Manual Mode.