Null/Peak Point LN Modulator Bias Controller, Dedicated for Intensity Modulator
Modulator bias controller is specially designed for Mach-Zehnder modulators to ensure a stable operation state in various operating environments.Based on its fully digitized signal processing method, the controller can provide ultra-stable performance.
The controller injects a low frequency, low amplitude dither signal together with a bias voltage into the modulator. It keeps reading the output from the modulator and determines the condition of the bias voltage and related error. A compensate bias voltage will be applied afterwards according to the previous measurements. In this way, the modulator is ensured to work under a proper bias voltage.
The controller is very compact in volume with high performance. The maximum stable DC extinction ratio measured in Lab is 50.4dB. The highest carrier suppression ratio measured is 43dB.
Feature
_ MZM bias control on Null and Peak modes
_ Low profile: 37mm(W) _ 25mm(D) _ 8mm(H)
_ High extinction ratio:
53dB Maximum1
50.4dB DC extinction ratio lab verified 2
43dB carrier suppression lab verified
_ Low dither amplitude: 0.1% V_
_ High stability: with fully digital implementation
_ Easy to use: Manual operation with mini jumper, Flexible OEM operations through UART3
_ Two different modes to output bias voltage: a. Automatic bias voltage b. User defined bias voltage
Applications
_ LiNbO3 and other MZ modulators
_ Brillouin scattering system and other optical sensors
_ Radio over Fiber systems
_ Pulse Generation
_ Carrier Suppression
Notes of requirements for high extinction ratio
1: System modulator must have high extinction ratio. Characteristic of system modulator decides the maximum extinction ratio can be achieved.
2: Polarization of modulator input light shall be taken care of. Modulators are sensitive to polarization. Proper polarization can improve extinction ratio over 10dB. In lab experiments, usually a polarization controller is needed.
3: Proper bias controllers. In our DC extinction ratio experiment, 50.4dB extinction ratio has been achieved. While the datasheet of the modulator manufacture only lists 40dB. The reason of this improvement is that some modulators drift very fast. MBC-NULL-03 bias controllers update the bias voltage every 1 second to ensure fast track response.
