HP 8169A User manual

User's Guide
HP 8169A Polarization Controller
SERIAL NUMBERS
This guide applies to all instruments.
ABCDE
HP Part No. 08169-91011
Printed in the Federal Republic of Germany
First Edition
E0396

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c
 Copyright 1993 by:
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Subject Matter
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First Edition : 1st September 1994 : 08169-91011 : E0994
: 1st March 1996 : 08169-91011 : E0396

Safety Summary
The following general safety precautions must be observed during all phases
of operation, service, and repair of this instrument. Failure to comply with
these precautions or with specic warnings elsewhere in this manual violates
safety standards of design, manufacture
, and intended use of the instrument.
Hewlett-Packard Company assumes no liability for the customer's failure to
comply with these requirements.
General This is a Safety Class 1 instrument (provided with terminal for
protective earthing) and has been manufactured and tested according to
international safety standards.
Operation - Before applying power Comply with the installation section.
Additionally, the following shall be observed:
Do not remove instrument covers when operating.
Before the instrument is switched on, all protective earth terminals
, extension
cords, auto-transformers and devices connected to it should be connected to a
protective earth via a ground socket. Any interruption of the protective earth
grounding will cause a potential shock hazard that could result in serious
personal injury.
Whenever it is likely that the protection has been impaired, the instrument
must be made inoperative and be secured against any unintended operation.
Make sure that only fuses with the required rated current and of the specied
type (normal blow, time delay, etc.) are used for replacement. The use of
repaired fuses and the short-circuiting of fuseholders must be avoided.
Adjustments described in the manual are performed with power supplied to
the instrument while protective covers are removed. Be aware that energy at
many points may, if contacted, result in personal injury.
Any adjustments, maintenance, and repair of the opened instrument under
voltage should be avoided as much as possible, and when unavoidable, should
be carried out only by a skilled person who is aware of the hazard involved.
Do not attempt internal service or adjustment unless another person, capable
of rendering rst aid and resuscitation is present. Do not replace components
with power cable connected.
Do not operate the instrument in the presence of ammable gases or fumes.
Operation of any electrical instrument in such an enviroment constitutes a
denite safety hazard.
Do not install substitute parts or perform any unauthorized modication to
the instrument.
Be aware that capacitors inside the instrument may still be charged even if
the instrument has been disconnected from its source of supply.
iv

Safety Symbols
The apparatus will be marked with this symbol when it is
necessary for the user to refer to the instruction manual in
order to protect the apparatus against damage.
Caution, risk of electric shock.
Frame or chassis terminal.
Protective conductor terminal.
Hazardous laser radiation.
Warning
The WARNING sign denotes a hazard. It calls attention to
a procedure, practice or the like, which, if not correctly
performed or adhered to, could result in injury or loss of
life. Do not proceed beyond a WARNING sign until the
indicated conditions are fully understood and met.
Caution
The CAUTION sign denotes a hazard. It calls attention to
an operating procedure, practice or the like, which, if not
correctly performed or adhered to, could result in damage to
or destruction of part or all of the equipment. Do not proceed
beyond a CAUTION sign until the indicated conditions are fully
understood and met.
v

Contents
1. Getting Started
The Basic Operating Principle ................. 1-1
Using the Polarization Controller for Polarization Analysis ... 1-2
Editing ............................ 1-3
Editing Using the Entry Keys . . . . . . . . . . . . . . . . . 1-3
Editing Using the Modify Keys and Knob ........... 1-3
Resetting Parameters . . . . . . . . . . . . . . . . . . . . . 1-4
2. Setting a State of Polarization
Setting up the Hardware . . . . . . . . . . . . . . . . . . . . 2-1
Setting the Position of the Polarizing Filter .......... 2-1
Setting the State of Polarization ................ 2-3
Positioning the  /4 and  /2 Retarder Plates .......... 2-4
Using the Circle Mode .................... 2-4
Example: Setting the Optimum Transmission SoP .. .. .. 2-4
Set the Polarizing Filter ................. 2-5
Setting the Worst Case Transmission SoP .. .. .. .. . 2-6
Setting the Optimum Transmission SoP ...... .. .. 2-7
3. Scanning the Poincare Sphere
Setting up the Hardware . . . . . . . . . . . . . . . . . . . . 3-1
Setting Up and Executing a Scan ................ 3-1
Example: Measuring the Response to a \Depolarized" Signal .. 3-2
Set the Polarizing Filter .. .. .. .. .. .. .. .. .. 3-3
Setting Up the Instruments . . . . . . . . . . . . . . . . . 3-4
Running the Scan .. .. .. .. .. .. . .. .. .. .. 3-4
Example: Measuring a Polarization Dependent Loss ...... 3-5
Set the Polarizing Filter .. .. .. .. .. .. .. .. .. 3-6
Setting Up the Instruments . . . . . . . . . . . . . . . . . 3-7
Running the Scan .. .. .. .. .. .. . .. .. .. .. 3-7
Analyzing the Results .. .. .. .. .. .. .. .. .. . 3-7
Contents-1

4. Other Front Panel Functions
Setting the HP-IB Address .. .. .. .. .. .. .. .. .. . 4-1
Storing or Recalling Instrument Settings . . . . . . . . . . . . . 4-1
Storing a Setting . . . . . . . . . . . . . . . . . . . . . . . 4-1
Recalling a Setting . . . . . . . . . . . . . . . . . . . . . . 4-2
Resetting the Instrument . . . . . . . . . . . . . . . . . . . 4-2
5. Programming the Polarization Controller
HP-IB Interface ........................ 5-1
Setting the HP-IB Address .. .. .. .. .. .. .. .. .. . 5-3
Returning the Instrument to Local Control ........... 5-3
How the Polarization Controller Receives and Transmits Messages 5-3
How the Input Queue Works ................. 5-3
Clearing the Input Queue . . . . . . . . . . . . . . . . . . 5-4
The Output Queue . . . . . . . . . . . . . . . . . . . . . . 5-4
The Error Queue . . . . . . . . . . . . . . . . . . . . . . . 5-4
Some Notes about Programming and Syntax Diagram Conventions 5-4
Short Form and Long Form.................. 5-5
Command and Query Syntax ................. 5-5
6. Remote Commands
Command Summary ...................... 6-2
The Common Commands . . . . . . . . . . . . . . . . . . . . 6-5
Common Status Information .. .. .. .. .. .. .. .. . 6-5
SRQ, The Service Request .... .. .. .. .. .. .. . 6-6
*CLS .... .. .. .. .. .. .. .. .. .. .. .. .. 6-7
*ESE ............................ 6-7
*ESE? . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
*ESR? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8
*IDN? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-9
*OPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10
*OPC? .... .. .. .. .. .. .. .. . .. .. .. . 6-10
*RCL ............................ 6-10
*RST .... .. .. .. .. .. .. .. .. .. .. .. .. 6-11
*SAV ............................ 6-11
*SRE .... .. .. .. .. .. .. .. .. .. .. .. .. 6-12
*SRE? . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-12
*STB? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
*TST? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
*WAI .. .. .. .. .. .. .. .. .. .. .. .. .. .. 6-14
Switching On and O the Instrument Display .. .. .. .. .. 6-15
Contents-2

:DISPlay:ENABle ...................... 6-15
:DISPlay:ENABle? . . . . . . . . . . . . . . . . . . . . . 6-15
Positioning the Polarizing Filter . . . . . . . . . . . . . . . . . 6-16
[:INPut]:POSition:POLarizer .... .. .. .. .. .. .. . 6-16
[:INPut]:POSition:POLarizer? . . . . . . . . . . . . . . . . 6-16
Setting the State of Polarization ................ 6-17
[:INPut]:CIRCle:EPSilonb . . . . . . . . . . . . . . . . . . . 6-17
[:INPut]:CIRCle:EPSilonb? ................. 6-17
[:INPut]:CIRCle:THETap ................... 6-18
[:INPut]:CIRCle:THETap?.................. 6-18
[:INPut]:POSition:HALF ................... 6-19
[:INPut]:POSition:HALF? . . . . . . . . . . . . . . . . . . 6-19
[:INPut]:POSition:QUARter . . . . . . . . . . . . . . . . . . 6-19
[:INPut]:POSition:QUARter? ................ 6-20
Scanning the Sphere . . . . . . . . . . . . . . . . . . . . . . 6-21
[:INPut]:PSPHere:RATE .. .. .. .. .. .. .. .. .. . 6-21
[:INPut]:PSPHere:RATE?.................. 6-21
:INITiate[:IMMediate] .................... 6-21
:ABORt . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-21
STATus Commands . . . . . . . . . . . . . . . . . . . . . . . 6-23
Setting Up the STATus Registers .... .. .. .. .. .. . 6-24
:STATus:PRESet ...................... 6-24
:STATus:OPERation:NTRansition .. .. .. .. .. .. .. 6-25
:STATus:OPERation:NTRansition? . . . . . . . . . . . . . 6-25
:STATus:OPERation:PTRansition .............. 6-25
:STATus:OPERation:PTRansition? . . . . . . . . . . . . . 6-25
:STATus:OPERation:ENABle .. .. .. .. .. .. .. .. 6-25
:STATus:OPERation:ENABle? . . . . . . . . . . . . . . . 6-26
:STATus:QUEStionable:NTRansition . . . . . . . . . . . . . 6-27
:STATus:QUEStionable:NTRansition? ........... 6-27
:STATus:QUEStionable:PTRansition .. .. .. .. .. .. . 6-27
:STATus:QUEStionable:PTRansition? .. .. .. .. .. . 6-27
:STATus:QUEStionable:ENABle . . . . . . . . . . . . . . . 6-27
:STATus:QUEStionable:ENABle? .. .. .. .. .. .. . 6-28
Checking the Status ...... .. .. .. .. .. .. . .. 6-29
:STATus:OPERation:CONDition? .............. 6-29
:STATus:OPERation[:EVENt]? . . . . . . . . . . . . . . . . 6-29
:STATus:QUEStionable:CONDition? ............. 6-30
:STATus:QUEStionable[:EVENt]? .............. 6-30
SYSTem Commands .. .. .. .. .. .. .. .. .. .. .. 6-31
:SYSTem:ERRor? . . . . . . . . . . . . . . . . . . . . . . . 6-31
Contents-3

:SYSTem:VERSion? . . . . . . . . . . . . . . . . . . . . . . 6-31
7. Programming Examples
Example 1 - Checking Communication ............. 7-2
Example 2 - Status Registers and Queues ............ 7-3
Example 3 - Finding the Optimum Transmission SoP . . . . . . . 7-7
Example 4 - Finding the Polarization Dependence ........ 7-11
A. Installation
Safety Considerations ..................... A-1
Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . A-1
AC Line Power Supply Requirements .............. A-2
Line Power Cable ...................... A-2
Replacing the Fuse . . . . . . . . . . . . . . . . . . . . . . A-4
Replacing the Battery .................... A-5
Operating and Storage Environment .............. A-5
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . A-6
Humidity .......................... A-6
Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . A-6
Installation Category and Pollution Degree .......... A-6
Instrument Positioning and Cooling . . . . . . . . . . . . . . A-6
Switching on the Polarization Controller . . . . . . . . . . . . . A-7
Optical Output . . . . . . . . . . . . . . . . . . . . . . . . . A-7
Trigger Input and Output . . . . . . . . . . . . . . . . . . . . A-8
HP-IB Interface ........................ A-8
Connector . . . . . . . . . . . . . . . . . . . . . . . . . . A-9
HP-IB Logic Levels . . . . . . . . . . . . . . . . . . . . . . A-9
Claims and Repackaging .................... A-10
Return Shipments to HP ................... A-10
B. Accessories
Instrument and Options .. .. .. .. .. .. .. .. .. .. B-1
HP-IB Cables and Adapters . . . . . . . . . . . . . . . . . . . B-1
Connector Interfaces and Other Accessories . . . . . . . . . . . B-2
Option 021, Straight Contact Connector . . . . . . . . . . . . B-2
Option 022, Angled Contact Connector ............ B-3
Contents-4

C. Specications
Specications ......................... C-1
Other Specications ...................... C-3
Declaration of Conformity ................... C-4
D. Performance Test
Insertion Loss Variation with Rotation of  /4 and  /2 Plates ... D-2
Insertion Loss versus Wavelength . . . . . . . . . . . . . . . . D-5
Extinction Ratio of Polarizer .................. D-10
E. Cleaning Procedures
Cleaning Materials . . . . . . . . . . . . . . . . . . . . . . . E-1
Cleaning Fiber/Front-Panel Connectors .. .. .. .. . .. .. E-2
Cleaning Connector Interfaces .. .. .. .. .. .. .. . .. E-2
Cleaning Connector Bushings . . . . . . . . . . . . . . . . . . E-3
Cleaning Detector Windows .................. E-3
Cleaning Lens Adapters .... .. .. .. .. .. .. .. .. E-3
Cleaning Detector Lens Interfaces .. .. .. .. .. .. .. . E-4
F. Error Messages
Display Messages .... .. .. .. .. .. .. .. .. .. . F-1
HP-IB Messages ........................ F-2
Command Errors . . . . . . . . . . . . . . . . . . . . . . . F-2
Execution Errors ...................... F-5
Device-Specic Errors .... .. .. .. .. .. .. .. .. F-6
Query Errors ........................ F-7
Index
Contents-5

Figures
6-1. Common Status Registers . . . . . . . . . . . . . . . . . . . 6-6
6-2. The Status Registers . . . . . . . . . . . . . . . . . . . . . 6-24
A-1. Line Power Cables - Plug Identication ............ A-2
A-2. Rear Panel Markings . . . . . . . . . . . . . . . . . . . . . A-4
A-3. Releasing the Fuse Holder .. .. .. .. .. .. .. .. .. A-4
A-4. The Fuse Holder . . . . . . . . . . . . . . . . . . . . . . . A-5
A-5. Correct Positioning of the Polarization Controller ....... A-7
A-6. HP-IB Connector . . . . . . . . . . . . . . . . . . . . . . . A-9
B-1. Straight Contact Connector Conguration . . . . . . . . . . . B-2
B-2. Angled Contact Connector Conguration ........... B-3
D-1. Test Setup for Measuring the Insertion Loss .......... D-2
D-2. Test Setup for Measuring the Reference Power . . . . . . . . . D-7
D-3. Test Setup for Measuring the Extinction Ratio . . . . . . . . . D-10
Tables
5-1. HP-IB Capabilities .. .. .. .. .. .. .. .. .. .. .. 5-2
6-1. Common Command Summary . . . . . . . . . . . . . . . . . 6-2
6-2. Command List . . . . . . . . . . . . . . . . . . . . . . . . 6-3
6-3. Reset State (Default Setting) ................. 6-11
A-1. Temperature . . . . . . . . . . . . . . . . . . . . . . . . . A-6
D-1. Equipment used: .... .. .. .. .. .. .. . .. .. . D-1
Contents-6

1
1
Getting Started
This chapter describes the basic operating principle, and the basic operating of
the polarization controller.
The Basic Operating Principle
The HP 8169A Polarization Controller transforms polarization relative to a built
in linear polarizer.
This means that the optical input is passed through a linear polarizer (P
ol), to
extract a single linear polarization.
Block Diagram and Polarization States (non-polarized ! linear polarized)
You should position this plate to get the maximum from the incoming signal
(attach a power meter to the output, and set the angle).
The  /4 and the  /2 plates are then positioned to control the relative state of
polarization of this signal.
Getting Started 1-1

1
Block Diagram and Polarization States (linear polarized ! elliptically
polarized)
You can either set the position of the plates directly, or use the circle application
to set the 2 "
B
and 2 
P
angles that dene the position on the Poincare Sphere.
In addition, using the sphere application, you can vary the angles of the  /4 and
the  /2 plates continuously. By varying the plate positions slowly, and sampling
the response of your Device Under Test, you can nd the maximum and
minimum power levels, and thus make polarization dependent measurements.
By varying the plate positions quickly, and averaging over all the states of
polarization, you can measure the response of your DUT to a \depolarized"
signal.
Using the Polarization Controller for Polarization Analysis
It is also possible to use the polarization controller to analyze the polarization
of a signal. To do this you attach your incoming signal to the  /2 connector, and
attach your power meter to the Pol connector.
Block Diagram for Polarization Analysis
1-2 Getting Started

1
You analyze the signal by varying the  /4 and  /2 plates and the polorizer lter,
and examining how this aects the power. It is beyond the scope of this manual
to explain this topic in detail.
Editing
You can edit a parameter by using
the Entry keys,
the Cursor/Vernier keys,or
the Modify knob.
Editing Using the Entry Keys
1. Make sure the correct parameter is selected (the label of the selected
parameter is displayed inverse).
2. Type in the new value.
3. Press 4
Enter
5 .
If you mistype the number, you can move the cursor left and right using the
Cursor keys ( 4
(
5 and 4
)
5 ).
If you want to abort editing, without changing the parameter, press
NNNNNNNNNNNNNNNNNNNN
Cancel .
If the parameter changes back to its old value when you press 4
Enter
5 , then the
new value would be out of the range allowed for that parameter.
Editing Using the Modify Keys and Knob
1. Make sure the correct parameter is selected (the label of the selected
parameter is displayed inverse).
2. Press any of the Cursor/Vernier keys, to activate editing.
3. Use the Cursor keys ( 4
(
5 and 4
)
5 ) to move to the rst digit you want to edit.
4. Change the value using the Vernier keys ( 4
*
5 and 4
+
5 ).
OR
Change the value using the Modify knob.
Getting Started 1-3

1
5. Repeat steps list item 3 to list item 4 as often as necessary.
6. Press 4
Enter
5 .
If you want to abort editing, without changing the parameter, press
NNNNNNNNNNNNNNNNNNNN
Cancel .
If you cannot change a digit with the Vernier keys or the Modify knob, this
means that the new value would be out of the range allowed for the parameter.
Resetting Parameters
To reset any parameter
1. Make sure the correct parameter is selected (the label of the selected
parameter is displayed inverse).
2.
Press
NNNNNNNNNNNNNNNNNNNNNNN
Default .
To reset Pol ,  /4 ,  /2 , 2 "
B
, AND 2 
P
simultaneously, press 4
Home
5 .
1-4 Getting Started

2
2
Setting a State of Polarization
This chapter describes the two ways of setting a State of Polarization,
By positioning the polarizing lter, the  /2, and the  /4 plates.
By positioning the polarizing lter, and then specifying the desired position on
the Poincare sphere.
Setting up the Hardware
Note
When you are setting up your hardware, it is absolutely vital
that the bers are xed, and remain unmoved for the whole
of the measurement. Moving the bers changes the state of
polarization.
Typically, you will connect the polarization controller directly after your source,
and before your device under test (DUT). Before connecting to the rest of your
measurement setup, you should set the position of the polarizing lter.
Setting the Position of the Polarizing Filter
The polarizing lter should be set to maximize the signal. This means aligning
the polarizing lter with the greatest linear polarization of the source. (Light
from laser sources is elliptically polarized).
Setting a State of Polarization 2-1

2
Power as a function of the angle of linear polarization for laser light
1. Connect the output of the polarization controller to a power meter.
Setup for maximizing the test signal
2. With all the instruments turned on, press 4
Home
5 on the polarization
controller. This resets the positions of all the plates.
3.
Select the polarization lter.You may need to press 4
Pos
5 and/or
NNNNNNNNNNN
Pol if the
lter is not already selected.
4. Move the lter to nd the maximum signal through the polarization
controller. One way of doing this is
a. Press the right Cursor key twice to select the units digit.
b. Watching the power meter, and using the Modify knob, adjust the angle of
the polarization lter, until you are in the area of one of the maxima.
c. Select the tenths digit.
d. Watching the power meter, and using the Modify knob, adjust the angle of
the polarization lter, until you nd the maximum.
e. Select the hundredths digit, and adjust the angle of the polarization lter
if necessary to get the absolute maximum.
2-2 Setting a State of Polarization

2
5. Disconnect the power meter, and connect to your DUT, and the rest of your
measurement setup, making sure to move the bers as little as possible.
Setting the State of Polarization
The state of polarization of a signal can be described by a position on the
Poincare sphere. This position is can be expressed in spherical coordinates by
two angles, called "
B
and 
P
.

P
is the optical angle about the 'equator' of the sphere (that is,2 
P
is the
angle of 'longitude').
"
B
is half the angle of elevation from the equatorial plane (that is,2 "
B
is the
angle of 'latitude').
The coordinates for describing the state of polarization
The state of polarization is always relative to the output from the polarizing
lter.
There are two ways of setting the state of polarization,
by specifying the position of the  /4 and  /2 retarder plates,or
by specifying "
B
and 
P
, the coordinates on the Poincare sphere.
Setting a State of Polarization 2-3

2
Positioning the  /4 and  /2 Retarder Plates
You can set the state of polarization by positioning the  /4, and  /2 plates.
1. Select a retarder plate
.You may need to press 4
Pos
5 rst to get the display
with the plates.
Press
NNNNNNNNNNN
 /4 or
NNNNNNNNNNN
 /2 if the plate you want is not already selected.
2. Move the plate to the position you want. (See \Editing" in Chapter 1 if you
need information on changing the angles).
Using the Circle Mode
You can set the state of polarization by specifying the coordinates on the
Poincare sphere. See \Setting the State of Polarization" for an explanation.
1. Select an angle.You may need to press 4
Circle
5 rst to get the display with the
angles.
Press
NNNNNNNNNN
2 "
B
or
NNNNNNNNNN
2 
P
if the angle you want is not already selected.
2. Change the angle to the value you want. (See \Editing" in Chapter 1 if you
need information on changing the angles).
Example: Setting the Optimum Transmission SoP
To nd the state of polarization which gives optimum transmission for a linear
device under test (DUT), the steps are
i. Set the polarizing lter.
ii. Find the state of polarization for worst case transmission (this is easier to
nd, because the resolution allows greater accuracy at lower power).
iii. Set the state of polarization for optimum transmission.
For this example, you will need, apart from the polarization controller, a laser
source, and a power meter (in the description below, an HP 8153A Multimeter
with a laser module and a sensor module are used). We will use the length of
ber connecting the instruments as our linear DUT.
1. With both instruments switched o, connect the laser source to the
polarization controller.
2. Connect the polarization controller to the power meter.
2-4 Setting a State of Polarization