Agilent Technologies 83438A User Manual

Agilent 83438A Erbium ASE Source User’s Guide

Agilent Part No. 83438-90010 Printed in USA February 2000

Agilent Technologies Lightwave Division 1400 Fountaingrove Parkway Santa Rosa, CA 95403-1799, USA (707) 577-1400

Notice.

The information contained in this document is subject to change without notice. Companies, names, and data used in examples herein are fictitious unless otherwise noted. Agilent Technologies makes no warranty of any kind with regard to this material, including but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material.

Restricted Rights Legend.

Use, duplication, or disclosure by the U.S. Government is subject to restrictions as set forth in subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 for DOD agencies, and subparagraphs (c) (1) and (c) (2) of the Commercial Computer Software Restricted Rights clause at FAR 52.227-19 for other agencies.

Warranty.

This Agilent Technologies instrument product is warranted against defects in

material and workmanship for a period of one year from date of shipment. During the warranty period, Agilent Technologies will, at its option, either repair or replace products which prove to be defective. For warranty service or repair, this product must be returned to a service facility designated by Agilent Technologies. Buyer shall prepay shipping charges to Agilent Technologies and Agilent Technologies shall pay shipping charges to return the product to Buyer. However, Buyer shall pay all shipping charges, duties, and taxes for products returned to Agilent Technologies from another country.

Agilent Technologies warrants that its software and firmware designated by Agilent Technologies for use with an instrument will execute its programming instructions when properly installed on that instrument. Agilent Technologies does not warrant that the operation of the instrument, or software, or firmware will be uninterrupted or errorfree.

Limitation of Warranty.

The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer, Buyersupplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental specifications for the product, or improper site preparation or maintenance.

No other warranty is expressed or implied. Agilent Technologies specifically disclaims the implied warranties of merchantability and fitness for a particular purpose.

Exclusive Remedies.

The remedies provided herein are buyer's sole and exclusive remedies. Agilent Technolo-

gies shall not be liable for any direct, indirect, special, incidental, or consequential damages, whether based on contract, tort, or any other legal theory.

Safety Symbols.

CAUTION

The

caution

sign denotes a hazard. It calls attention to a procedure which, if not correctly performed or adhered to, could result in damage to or destruction of the product. Do not proceed beyond a caution sign until the indicated conditions are fully understood and met.

WAR NING

The

warning

sign denotes a hazard. It calls attention to a procedure 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.

The instruction manual symbol. The product is marked with this warning symbol when it is necessary for the user to refer to the instructions in the manual.

The laser radiation symbol. This warning symbol is marked on products which have a laser output.

The AC symbol is used to indicate the required nature of the line module input power.

The ON symbols are

used to mark the positions of the instrument power line switch.

The OFF symbols

❍

are used to mark the positions of the instrument power line switch.

The CE mark is a registered trademark of the European Community.

The CSA mark is a registered trademark of the Canadian Standards Association.

The C-Tick mark is a registered trademark of the Australian Spectrum Management Agency.

This text denotes the

ISM1-A

instrument is an Industrial Scientific and Medical Group 1 Class A product.

Typographical Conventions.

The following conventions are used in this book:

Key type

for keys or text located on the keyboard or instrument.

Softkey type

for key names that are displayed on the instrument’s screen.

Display type

for words or characters displayed on the computer’s screen or instrument’s display.

User type

for words or charac-

ters that you type or enter.

Emphasis

type for words or characters that emphasize some point or that are used as place holders for text that you type.

The Agilent 83438A—At a Glance

The Agilent 83438A Erbium ASE Source provides incoherent light for characterizing fiber-optic components. Its output is centered at approximately 1550 nm. Because it has a relatively high-power spectral density, you can probe devices with medium or high insertion loss. Its single-mode output originates from the amplified spontaneous emission (ASE) of an Erbium doped fiber amplifier. The power spectral density of the output is up to one hundred times (20 dB) greater than that of edge emitting LEDs (for example, the Agilent 83437A Broadband Light Source) and up to 100,000 times (50 dB) greater than white-light tungsten lamp sources. An internal optical isolator protects the Agilent 83438A from back reflections from the device under test. This greatly improves the power stability of the Agilent 83438A.

Block Diagram of Agilent 83438A

iii

The Agilent 83438A—At a Glance

The output can be modulated or turned off

You can digitally modulate the output using a TTL compatible signal. For a complete discussion of modulating the output light and making measurements with your Agilent 83438A, refer to Chapter 2, “Making Measurements”.

Measurement accuracy—it’s up to you!

Fiber-optic connectors are easily damaged when connected to dirty or damaged cables and accessories. The Agilent 83438A’s front-panel OPTICAL OUT connector is no exception. When you use improper cleaning and handling techniques, you risk expensive instrument repairs, damaged cables, and compromised measurements.

Before you connect any fiber-optic cable to the Agilent 83438A, refer to “Cleaning Con-

nections for Accurate Measurements” on page 2-11.

Laser classification

The Agilent 83438A is classified as an IEC LASER Class 1. The total power of light energy radiated out of the OPTICAL OUT connector is no greater than +8.1 dBm (6.5 mW) at a wavelength of 1550 nm. Operator maintenance or precautions are not necessary to maintain safety. No controls, adjustments, or performance of procedures result in hazardous radiation exposure.

The Agilent 83438A—At a Glance

Rear view of instrument

General Safety Considerations

This product has been designed and tested in accordance with IEC Publication 61010-1, Safety Requirements for Electrical Equipment for Measurement, Control and Laboratory Use, and has been supplied in a safe condition. The instruction documentation contains information and warnings that must be followed by the user to ensure safe operation and to maintain the product in a safe condition.

WARNING

If this instrument is not used as specified, the protection provided by the equipment could be impaired. This instrument must be used in a normal condition (in which all means for protection are intact) only.

To prevent electrical shock, disconnect the Agilent 83438A from mains before cleaning. Use a dry cloth or one slightly dampened with water to clean the external case parts. Do not attempt to clean internally.

This is a Safety Class 1 product (provided with a protective earthing ground incorporated in the power cord). The mains plug shall only be inserted in a socket outlet provided with a protective earth contact. Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous. Intentional interruption is prohibited.

No operator serviceable parts inside. Refer servicing to qualified personnel. To prevent electrical shock, do not remove covers.

For continued protection against fire hazard, replace line fuse only with same type and ratings, (type T 0.315A/250V for 100/120V operation and 0.16A/250V for 220/240V operation). The use of other fuses or materials is prohibited. Verify that the value of the linevoltage fuse is correct.

• For 100/120V operation, use an IEC 127 5×20 mm, 0.315 A, 250 V, Agilent part number 2110-0449.

• For 220/240V operation, use an IEC 127 5×20 mm, 0.16 A, 250 V, Agilent Technologies part number 2110-0448.

General Safety Considerations

CAUTION

Before switching on this instrument, make sure that the line voltage selector switch is set to the line voltage of the power supply and the correct fuse is installed. Assure the supply voltage is in the specified range.

This product is designed for use in Installation Category II and Pollution Degree 2 per IEC 1010 and 664 respectively.

VENTILATION REQUIREMENTS: When installing the product in a cabinet, the convection into and out of the product must not be restricted. The ambient temperature (outside the cabinet) must be less than the maximum operating temperature of the product by 4°C for every 100 watts dissipated in the cabinet. If the total power dissipated in the cabinet is greater than 800 watts, then forced convection must be used.

Always use the three-prong ac power cord supplied with this instrument. Failure to ensure adequate earth grounding by not using this cord may cause instrument damage.

Do not

connect ac power until you have verified the line voltage is correct as described in “Line Power Requirements” on page 1-6. Damage to the equipment could result.

This instrument has autoranging line voltage input. Be sure the supply voltage is within the specified range.

vii

The Agilent 83438A—At a Glance iii

1 Getting Started

Step 1. Inspect the Shipment 1-4 Step 2. Check the Fuse 1-5 Step 3. Connect the Line-Power Cable 1-6 Step 4. Turn on the Agilent 83438A 1-7 Returning the Instrument for Service 1-8

2 Making Measurements

Performing Stimulus-Response Measurements 2-3 Ambient Light Suppression 2-7 Modulating the Output Light 2-10 Cleaning Connections for Accurate Measurements 2-11

3 Specifications and Regulatory Information

Specifications 3-3 Regulatory Information 3-6

4 Reference

Instrument Options 4-2 Accessories 4-2 Front-Panel Fiber-Optic Adapters 4-3 Power Cords 4-4 Agilent Technologies Service Offices 4-5

5Servicing

General Information 5-4 Electrostatic Discharge Information 5-10 Troubleshooting 5-12 Performance Tests 5-20 Adjustment Procedure 5-23 Replacing Instrument Assemblies 5-26 Replaceable Parts 5-35

Contents-1

Step 1. Inspect the Shipment 1-4 Step 2. Check the Fuse 1-5 Step 3. Connect the Line-Power Cable 1-6 Step 4. Turn on the Agilent 83438A 1-7 Returning the Instrument for Service 1-8

Getting Started

The instructions in this chapter show you how to install your Agilent 83438A. You should be able to finish these procedures in about ten to twenty minutes. After you’ve completed this chapter, continue with Chapter 2, “Making Mea- surements”.

Refer to Chapter 3, “Specifications and Regulatory Information” for information on operating conditions such as temperature.

If you should ever need to clean the cabinet, use a damp cloth only.

WARNING

CAUTION

This is a Safety Class I product (provided with a protective earthing ground incorporated in the power cord). The mains plug shall only be inserted in a socket outlet provided with a protective earth contact. Any interruption of the protective conductor inside or outside of the product is likely to make the product dangerous. Intentional interruption is prohibited.

This product has autoranging line voltage input. Be sure the supply voltage is within the specified range.

This product is designed for use in INSTALLATION CATEGORY II and POLLUTION DEGREE 2, per IEC 1010 and 664 respectively.

1-2

Getting Started

Measurement accuracy—it’s up to you!

Fiber-optic connectors are easily damaged when connected to dirty or damaged cables and accessories. The Agilent 83438A’s front-panel OPTICAL OUT connector is no excep- tion. When you use improper cleaning and handling techniques, you risk expensive instrument repairs, damaged cables, and compromised measurements.

Before you connect any fiber-optic cable to the Agilent 83438A, refer to “Cleaning Connections for Accurate Measurements” on page 2-11.

1-3

Getting Started

Step 1. Inspect the Shipment

Verify that all components ordered have arrived by comparing the shipping forms to the original purchase order. Inspect all shipping containers.

If your shipment is damaged or incomplete, save the packing materials and notify both the shipping carrier and the nearest Agilent Technologies service office. Agilent Technologies will arrange for repair or replacement of damaged or incomplete shipments without waiting for a settlement from the transportation company. Notify the Agilent Technologies customer engineer of any problems.

Make sure that the serial number and options listed on the instrument’s rear- panel label match the serial number and options listed on the shipping document. The following figure is an example of the rear-panel serial number label:

Table 1-1. Agilent 83438A Options

Option Description

009 Built-in polarizer

011 Diamond HMS-10 fiber-optic input connector interface

013 DIN 47256 fiber-optic input connector interface

014 ST fiber-optic input connector interface

017 SC fiber-optic input connector interface

022 Angled contact fiber-optic output interface

1-4

Step 2. Check the Fuse

Locate the line-input connector on the instrument’s rear panel.

Disconnect the line-power cable if it is connected.

Use a small flat-blade screwdriver to open the pull-out fuse drawer.

Getting Started

WARNING

Verify that the value of the line-voltage fuse in the pull-out drawer is correct. The recommended fuse is an IEC 127 5×20 mm, 6.3A, 250 V, Agilent part number 2110-0703.

Notice that an extra fuse is provided in a drawer located on the fuse holder.

For continued protection against fire hazard, replace line fuse only with same type and ratings, (type T 6.3A/250V for 100/240V operation). The use of other fuses or materials is prohibited.

1-5

Getting Started

Step 3. Connect the Line-Power Cable

CAUTION

Always use the three-prong AC power cord supplied with this instrument. Failure to ensure adequate earth grounding by not using this cord may cause instrument damage.

Do not

connect ac power until you have verified the line voltage is correct as

described in the following paragraphs. Damage to the equipment could result.

This instrument has autoranging line voltage input. Be sure the supply voltage is within the specified range.

Verify that the line power meets the requirements shown in the following table.

Line Power Requirements

Power: 115 VAC: 50 WATTS MAX.

230 VAC: 50 WATTS MAX.

Voltage nominal: 115 VAC / 230 VAC

range 115 VAC: 90-132 V range 230 VAC: 198-254 V

Frequency nominals: 50 Hz / 60 Hz

range: 47-63 Hz

Connect the line-power cord to the instrument’s rear-panel connector.

Connect the other end of the line-power cord to the power receptacle.

Various power cables are available to connect the Agilent 83438A to ac power outlets unique to specific geographic areas. The cable appropriate for the area to which the Agilent 83438A is originally shipped is included with the unit. You can order additional ac power cables for use in different geographic areas. Refer to “Power Cords” on page 4-4.

1-6

Step 4. Turn on the Agilent 83438A

Getting Started

Press the front-panel

The front-panel ply after the EMC filters and before other parts of the instrument.

Use the front-panel

If the Agilent 83438A fails to turn on properly, consider the following possibilities:

• Is the line fuse good?

• Does the line socket have power?

• Is it plugged into the proper ac power source?

If the instrument still fails, return it to Agilent Technologies for repair. Refer to “Returning the Instrument for Service” on page 1-8.

LINE

key.

LINE

switch disconnects the mains circuits from the mains sup-

ACTIVE

key to turn the light output on and off.

1-7

Getting Started

Returning the Instrument for Service

The instructions in this section show you how to properly return the instrument for repair or calibration. Always call the Agilent Technologies Instrument Support Center first to initiate service service office. This ensures that the repair (or calibration) can be properly tracked and that your instrument will be returned to you as quickly as possible. Call this number regardless of where you are located. Refer to “Agilent Technologies Service Offices” on page 4-5 for a list of service offices.

Agilent Technologies Instrument Support Center . . . . . . . . . . . (800) 403-0801

If the instrument is still under warranty or is covered by an Agilent Technologies maintenance contract, it will be repaired under the terms of the warranty or contract (the warranty is at the front of this manual). If the instrument is no longer under warranty or is not covered by an Agilent Technologies maintenance plan, Agilent Technologies will notify you of the cost of the repair after examining the unit.

When an instrument is returned to a Agilent Technologies service office for servicing, it must be adequately packaged and have a complete description of the failure symptoms attached. When describing the failure, please be as specific as possible about the nature of the problem. Include copies of additional failure information (such as the instrument failure settings, data related to instrument failure, and error messages) along with the instrument being returned.

before

returning your instrument to a

Preparing the instrument for shipping

Write a complete description of the failure and attach it to the instrument. Include any specific performance details related to the problem. The following

1-8

Getting Started

Returning the Instrument for Service

information should be returned with the instrument.

• Type of service required.

• Date instrument was returned for repair.

• Description of the problem:

• Whether problem is constant or intermittent.

• Whether instrument is temperature-sensitive.

• Whether instrument is vibration-sensitive.

• Instrument settings required to reproduce the problem.

• Performance data.

• Company name and return address.

• Name and phone number of technical contact person.

• Model number of returned instrument.

• Full serial number of returned instrument.

• List of any accessories returned with instrument.

Cover all front or rear-panel connectors that were originally covered when you first received the instrument.

CAUTION

Cover electrical connectors to protect sensitive components from electrostatic damage. Cover optical connectors to protect them from damage due to physical contact or dust.

Instrument damage can result from using packaging materials other than the original materials. Never use styrene pellets as packaging material. They do not adequately cushion the instrument or prevent it from shifting in the carton. They may also cause instrument damage by generating static electricity.

Pack the instrument in the original shipping containers. Original materials are available through any Agilent Technologies office. Or, use the following guidelines:

• Wrap the instrument in antistatic plastic to reduce the possibility of damage

caused by electrostatic discharge.

• For instruments weighing less than 54 kg (120 lb), use a double-walled, cor-

rugated cardboard carton of 159 kg (350 lb) test strength.

• The carton must be large enough to allow approximately 7 cm (3 inches) on

all sides of the instrument for packing material, and strong enough to accommodate the weight of the instrument.

• Surround the equipment with approximately 7 cm (3 inches) of packing ma-

terial, to protect the instrument and prevent it from moving in the carton. If packing foam is not available, the best alternative is S.D-240 Air Cap™ from

1-9

Getting Started

Returning the Instrument for Service

Sealed Air Corporation (Commerce, California 90001). Air Cap looks like a plastic sheet filled with air bubbles. Use the pink (antistatic) Air Cap™ to reduce static electricity. Wrapping the instrument several times in this material will protect the instrument and prevent it from moving in the carton.

Seal the carton with strong nylon adhesive tape.

Mark the carton “FRAGILE, HANDLE WITH CARE”.

Retain copies of all shipping papers.

1-10

Performing Stimulus-Response Measurements 2-3

To characterize a passive device 2-5

Ambient Light Suppression 2-7

To suppress ambient light 2-8 Modulating the Output Light 2-10 Cleaning Connections for Accurate Measurements 2-11

Making Measurements

In this chapter, you’ll find examples of making measurements using the Agilent 83438A. These examples use your Agilent 83438A in conjunction with an Agilent 71450/1/2B optical spectrum analyzer. This combination provides up to 70 dB of measurement range. And, because of the Agilent 83438A’s relatively high power density, the optical spectrum analyzer can sweep much faster than if a white light source, surface emitting LED, or even an EELED were used.

The last section of this chapter explains how to maintain top performance of your instrument by using proper handling and cleaning techniques. Be sure to read this section before using your Agilent 83438A.

2-2

Making Measurements

Performing Stimulus-Response Measurements

This section shows you how to perform stimulus-response measurements. The combination of using the Agilent 83438A for broadband stimulus and the optical spectrum analyzer for selective response provides the following benefits:

• All wavelengths are available simultaneously

• Fast measurement speeds

• Small coherence length

• High dynamic range and high resolution

Measurements for DWDM systems

The following figure shows a system which is well suited for characterizing dense wavelength-division multiplexed (DWDM) components. Because of the high-power density of the Agilent 83438A, you can easily characterize such items as the crosstalk of dimultiplexers and the reverse path of optical isolators.

The polarization controller is used to characterize polarization dependencies of a device. For example, the center wavelength shift or the polarization dependent loss of a demultiplexer. If your instrument has Option 009 installed, it contains a built-in polarizer.

Increasing wavelength accuracy

When measuring deep-notch filters, increased absolute wavelength accuracy may be required. To increase wavelength accuracy, the combination of an Agilent 8168E/F tunable laser source and the Agilent 86120A multi-wavelength meter can be used to calibrate the optical spectrum analyzer. Simply enter the difference between the two wavelength readings (optical spectrum analyzer and multi-wavelength meter) into the optical spectrum analyzer as a correction factor. Refer to the user’s guide for the optical spectrum analyzer to learn how to enter correction factors. If you use this technique, be aware that the Agilent 8168E/F measures wavelength in a vacuum and the optical spectrum analyzer measures wavelength in air unless you change its settings.

2-3

Making Measurements

Performing Stimulus-Response Measurements

2-4

Making Measurements

Performing Stimulus-Response Measurements

To characterize a passive device

Turn on the optical spectrum analyzer and the Agilent 83438A, and allow them to warm up for 1 hour.

Use a fiber optic cable to connect the Agilent 83438A’s output to the input of the optical spectrum analyzer.

On the optical spectrum analyzer, press

AUTO ALIGN

On the optical spectrum analyzer, use the wavelength range.

Press

Press beyond this value if needed.

If you are measuring a deep-notch filter, more sensitivity may be required. Perform the following steps:

Press

These steps cause the optical spectrum analyzer to compensate for the

effect of stray light inside the analyzer’s monochromator.

Press

REF LEVEL

SENS,

State

STORE THRU->B,

, and set the reference level to –10 dBm.

and set the sensitivity to –70 dBm. You can increase the sensitivity

Amptd

BW,Swp

instr modes

, and then

SWPTIME AutoMan

, and then

and then

CHOP On

STM/RESP

NORM On Off

INSTR PRESET, AUTO MEAS,

START

so that On is underlined.

, and set the sweep time to 50 seconds.

to normalize the response.

and

STOP

keys to set the proper

and then

2-5

Making Measurements

Performing Stimulus-Response Measurements

If changes to wavelength range or resolution bandwidth are made after this trace is stored, repeat this step.

Insert the device you are testing between the optical spectrum analyzer and the Agilent 83438A.

NORMAL ON/OFF

Press

to turn the marker on. Rotate the front-panel knob to

read the values along the response.

2-6

Making Measurements

Ambient Light Suppression

Ambient light can add significant errors to optical power measurements. This is especially true when you are using or characterizing open beam devices. The following example shows how the combination of the Agilent 83438A and an Agilent 71450/1/2B optical spectrum analyzer can be used to eliminate this error.

In order to perform this measurement, the Agilent 83438A’s output is modulated at 270 Hz. Because the optical spectrum analyzer has the ability to synchronize its data acquisition with the modulated light, it can subtract out the effects of ambient light. To learn more about using the optical spectrum analyzer’s adc trigger feature, refer to Agilent Technologies Product Note 71452–4, “Pulsed or Time-Dependent Optical Spectra Measurements.”

2-7

Making Measurements

Ambient Light Suppression

To suppress ambient light

This example uses specific equipment and settings to demonstrate how to make accurate measurements in the presence of ambient light. As shown in the equipment setup drawing, two Agilent 83438As are used. One Agilent 83438A represents the broadband contribution of ambient light. Because a 12 dB coupler is used, the ambient light contributes approximately 10 dB more power to the optical spectrum analyzer than the desired source.

Connect the equipment as shown in the following figure.

Set the square-wave generator for a frequency of 270 Hz. Set its voltage output to TTL levels.

The TTL low state is defined to be within 0 to 0.8 Vdc. The TTL high state is defined to be within 2.0 to 5 Vdc. If you use a different modulation frequency, set the optical spectrum analyzer’s resolution bandwidth to a value that is at least six times greater than the modulation frequency.

On the optical spectrum analyzer, press

Use the 1600 nm.

2-8

START

and

STOP

keys to set the wavelength range from 1500 nm to

INSTR PRESET

Making Measurements

Ambient Light Suppression

REF LEVEL

Press

Amptd

Press

MORE, CHOP On Off

Press

BW,Swp

Press

MORE, MORE, adc trigger

Press

ADCTRIG DELAY

Press

, and set the reference level to –10 dBm.

LOG dB/DIV

, and enter 5 dB.

so that Off is underlined.

SWPTIME AutoMan

, and set the sweep time to 10 seconds.

, and then

ADCTRIG AC

, and enter a value of 1 ms.

The display should now show the proper amplitude values with the effect of the ambient light subtracted out.

2-9

Making Measurements

Modulating the Output Light

The rear panel of the instrument is equipped with a tor. You can use this connector to digitally modulate the source for applications using lock-in techniques. (Refer to “Ambient Light Suppression” on page 2-7.) Or, you can completely disable its output light.

Digital modulation requires a TTL compatible signal. Modulation rates can range from DC to 300 Hz. A “high” TTL value turns the source on. A “low” TTL value turns the source off. The TTL low state is defined to be within 0 to

0.8 Vdc. The TTL high state is defined to be within 2.0 to 5 Vdc.

The following schematic shows the input circuitry for the connector.

If no signal is present on the on. If you want to turn the output off, simply connect a BNC short to the rearpanel modulation input. You can order a BNC short from Agilent Technologies using the following part number: 1250-0774.

MODULATION INPUT

connector, the source is turned

connec-

2-10

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