PSI-0204-99

Optical Modulator Bias Controller
Evaluation Kit
For use with PSI-0204-11 chip-scale MBC

PSI-0204-99 MBC Evaluation BoardFeatures and Benefits
Complete evaluation kit for PSI-0204-11
Modulator Bias Controller
Includes all control components to test
MBC with your application
Dither based control compatible withmost optical modulators
Includes sample MBC, AC power supply andDC electrical connectors.

Figure 2: Typical Modulator
Controller Application

Applications•••••••

Modulator design
Integrated Modulator/TransmittersFiber optic component evaluation
Photonic Test Systems
Spectroscopy systems
Analog communications systems
Telecom transmission

Product Description
The PSI—0204-99 optical modulator bias controller (MBC) evaluation kit provides a complete laboratory solution for evaluation of
the PSI-0204-11 chip-scale MBC. The chip-scale controller provides control of external optical modulators from a single, smallform factor circuit board.
When operated with lithium
niobate (LiNbO3), modulators, the PSI-0204-11 provides automatic or manualbias control. Users may select automatic tracking of
Quad +, Quad -, Minimum orMaximum bias points asFigure 1– Modulator Transfer Function
shown in Figure 1. Operation
at an externally set manual bias point may also be selected.
The chip-scale device evaluation board provides a simple means tomake all necessary electrical and optical connections to an MBC
under evaluation. A 24 pin socket on top of the board hosts thedevice under test. All electrical and optical connections are madeto the device including power, user-defined settings and bias voltage output. An on-board photodetector completes the optical feedback loop from a user’s modulator and laser system. Controls areprovided to set manual bias point, automatic bias point, bias offset, dither amplitude and dither frequency. Push buttons allow for
temporary hold of a bias point, dither disable and forced reset. A
bias monitor port is provided as are connections through either aD-type or Molex connector. The kit is shipped complete with a sample MBC, AC power supply, and connectors.
About the PSI-0204-11 Chip-scale MBC
Designed for easy integration into the user’s optical system, thesecontrollers maintain constantbias point operation by compensating for drift in a modulator’s transfer function. An external modulation fiber optical PSI-0204-11 Modulator Bias Controllertransmitter is shown in Figure 2 to illustrate how the controller istypically used. Through use of an optical coupler and photodetector, a portion of the transmitted light is detected and fed to theMBC. The dither tone is applied to the bias voltage output andsampled as a control mechanism. User settings determine bias
point selection, dither frequency and amplitude.
Beyond standard specifications, PSI can modify the PSI-0204-11
to meet the exact requirements of your application. Smaller package sizes are offered for operation at a single bias point; otherdesigns may also result in micro-miniature packages.

Phone: 978-670-4990
E-mail: info@photonicsinc.com
www.photonicsinc.com

PSI-0204-11

Chip scale Optical Modulator Bias
Controller
Specifications
Parameter

Typical Value

Units

Modulating Signal

Analog small or large signal or DPSK—

Modulators Supported

LiNbO3—Modulator/Bias-T Load Capacitance< 0.2μF

Output DC Bias Port Impedance

100ohms

Output DC Bias Voltage

0.3 less than supply voltageVolts

Dither Frequency

1KHz

20 to 200; user defined

mVpp

1 @1% dither of Vπdegrees

Bias Point Error @Max or Min point, 10 to 100 μa photo detector current 1< 0.1degrees

DC Power Supply+/- 12 to +/-18

Volts

DC Operating Current< 12mA

Operating Temperature Range

0 to +50

degrees C

MBC Board Dimensions

2.5 x 0.7 (6.4 x 1.7cm) ; 24 pin dual in-line
package, 0.6” widthinches

Dither Amplitude
Bias Point Error @Quad + or Quad - point, 5 to 50 μa photo detector current

11. Equivalent to -23 to -13 dBm of optical power (at quadrature) applied to Fermionics FD-300 or equivalent photo detector. Wider dynamic range
controllers available at additional cost; contact PSI for details.

+V-V

Photonic Systems,Inc. (PSI) is arecognized expert
in the design,
analysis andimplementation

PSI-0204-11 MBC Functional Block Diagramof high performance fiber opticsystems.
With decades ofcollective experi-

Feedback
control

DitherFrequency&Amplitude

Dither
Generator

ence, the PSI
team offers com-

Quad+, Quad-,
Min, Max control

prehensive fiber
optic engineeringsolutions togovernment,
military andcommercial cus-Bias Output

Automatic set
point control

Auto/Manual Selection&Control

PDtomers.

Phone: 978-670-4990
E-mail: info@photonicsinc.com
www.photonicsinc.com
Rev E 9/28/06; Specifications subject to change without notice-2-900 Middlesex Turnpike, Bldg 5Billerica, MA 01821

PSI-0204-11

Chip scale Optical Modulator BiasController
Modulator Bias Controller Device Function and Pin Descriptions
PinFunction

1PD Bias

2

PD Cathode

3GroundDevice Ground

4GroundDevice Ground

5MasterOutput of PD preamplifier. Normally connected to pin 6. May be used for control of slaved bias controllers.

6SlaveInput to dither detection circuitry. Normally connected to pin 5. May be used for control from a master bias controller.

7GroundDevice Ground

8Intg. In

Control loop integrator input. Normally unused, this input allows for modification of the bias control response time.

9-Intg. –B

Control loop integrator differential input. Normally connected to pin 10, this input allows for modification of the bias control responsetime.

10+Intg. +B

Control loop integrator differential input. Normally connected to pin 9, this input allows for modification of the bias control response
time.

11Bias Out

Bias output

12

Manual Bias In

13

Dither Out– Lo Adj

14

Dither In

Dither input. Normally connected to pin 15 through a user selectable resistance to set dither amplitude. May be used to implement
adjustable dither in conjunction with pin 15.

15

Dither Out Adj

Dither generator output. Normally connected to pin 14 through a user selectable resistance to set dither amplitude. May be used toimplement adjustable dither in conjunction with pin 14.

16

Auto Bias Select 2

Input to set auto bias point in conjunction with pin 17. See table 1 below. Device employs internal 200k pull up resistor.

17Auto Bias Select 1

Input to set auto bias point in conjunction with pin 16. See table 1 below. Device employs internal 200k pull up resistor.

18Freq. Adj (future use)

No connection- Dither frequency control in future release; not supported at this time.

19+Vlog Out

20Reset21

Auto/Manual Select

22-V

23

Ground24+V

Description
Provides internally generated bias voltage for photodetector. Normally connected together with Pin 2 to the PD cathode.
Photodetector cathode connection. Normally connected to Pin 1 for PD bias.

Input for control of bias in manual mode. Input voltage ranges from –V to + V for control of bias voltage over Max to Min.
Low dither voltage output. May be used for fine adjustment of dither amplitude. Normally not used.

4.5 volt reference output. Normally not used.
Control loop reset input. Ground for normal operation, allow high for reset; device employs 200k pull up resistor.
Selects Automatic or manual bias point control. Connect to ground for automatic control; open for manual control. Device employs
internal 200k pull up resistor.
Negative power supply connection. Acceptable range from –4.75 to –18 volts
Device Ground
Positive power supply connection. Acceptable range from 4.75 to 18 volts

Bias
Point

900 Middlesex Turnpike, Bldg 5Billerica, MA 01821

Phone: 978-670-4990
E-mail: info@photonicsinc.com
www.photonicsinc.com
Rev. E 9/28/06
Specifications subject to change without notice

MBC Pin Position
5Position
6

Q+OpenOpen

Q-

GroundOpenMax

Open

GroundMin

GroundGroundTable 1: Auto bias control point settings.

-3-PSI-0204-99 Modulator Bias Controller Evaluation Kit
Using the Evaluation BoardMost functions of the PSI-0204-99 Modulator Bias Controller evaluation board are set up through an 8position DIP switch bank (SW3) located at the lower right of the board. These switches enable the dithergenerator at a fixed frequency and amplitude, enable automatic reset, set the automatic bias control pointand determine set +/-15 volt supply operation. Prior to applying power to the evaluation board, ensurethat the switches are set according to your application and the tables below.

POSONMBC Pin Pin 17OFF (CLOSED)Pin 16

1

Adjustable Dither Frequency

Fixed Frequency (1KHz)

BiasPoint

2

Auto Reset Off

Auto Reset On

Q+OpenOpen

3Power= -15V

Power= -5V

Q-GroundOpen

4Power=+15V

Power=+5V

Max

Open

Ground5Bias Mode (See Table 2)

Bias Mode (See Table 2)Min

GroundGround6

Bias Mode (See Table 2)

Bias Mode (See Table 2)

7

Dither Low

Dither Off

8

Dither Adj. (P2)Dither Adj. Off
J8 or
J10 pin
123456789101112131415

Auto bias control point settings.

Description
Q+/Min/Max
Min+5 volts
Power Switch 1
Power Switch 2
Reset Input; Ground to force reset
Bias Output
Power Meter
Auto/manual SelectGroundBias Wiper (Manual Control)
VV+Power LED

All functions and interface points on the evaluation
board may be accessed in several ways. The controller’s output is accessible through either a BNC,SMA, D-sub or in-line connector. This allows for easy
connection to the modulator under control alongwith a monitoring instrument. All other functions
may be accessed through either the D-Sub (J10) orin-line connector (J8) as illustrated here.