Santec OTF-920 User manual

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OTF-920
Optical Tunable Filter
Operation Manual
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OTF-920 Operation Manual
This product has been produced in accordance with ISO-9001 international
quality system standards.
Disclaimer
Every effort has been made to ensure the information contained in this manual is accurate and easily
understandable. Santec shall not, however, be liable for errors contained herein, or for incidental or
consequential damages in connection with the use of this material.
Copyright 2000, Santec Corporation, Japan. No part of this document may be reproduced, stored in a
retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying,
recording, or otherwise without the prior written permission of Santec Corporation, Japan.
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OPTICAL TUNABLE FILTER OTF-920
This manual explains the operation and safety features of the OTF-920 Optical Tunable Filter. To
ensure the safe operation of the instrument, and to prevent the risk of personal injury and/or damage to
the equipment we recommend that you read the manual fully before commencing installation and
operation. In particular Chapter 6 outlines the precautions necessary to ensure safe operation. The
following safety symbols are used throughout the manual and on the equipment to indicate safety
related information.
DANGER!!
CAUTION
Packing Materials
The original packing materials are required to ensure the safe long term storage and safe transportation
of this equipment. It is recommended that all packing materials are kept for these purposes.
This indicates a dangerous procedure that could result in serious injury or
death if not performed properly.
This mark is used on the equipment as a warning of danger.
About This Manual
This indicates a hazardous procedure or danger that might result in injury or
that could damage the equipment if proper precautions are not taken.
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OTF-920 Operation Manual
About This Manual
1. Introduction
2. Specifications
3. Features
3.1. Wavelength Range
3.2. Peak Search Function
3.3. Optical Power Monitor
3.4. Optical Power Control
3.5. Wavelength Calibration
4. Principle of Operation
4.1. Wavelength Tuning / Setting
4.2. Peak Search Function
4.3. Wavelength Calibration
5. Panel Descriptions
5.1. Front Panel
5.2. Rear Panel
6. Safety Information
6.1 Mains Voltage
6.2 Installation
6.3 Safe Operation
Contents
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OPTICAL TUNABLE FILTER OTF-920
7. Operation Procedures
7.1. Power On / Off
7.2. Optical Fiber Connection
7.3. Setting Parameters
7.3.1. Setting using the Numeric Keypad.
7.3.2. Setting using the Up / Down Arrow Keys
7.4. Wavelength Tuning / Setting
7.5. Independent Slider Control (Option)
7.6. Peak Search
7.6.1. Setting Scan Range
7.6.2. Performing a Scan
7.7. Optical Power Control (Option)
7.7.1. Automatic Power Control (APC)
7.7.2. APC Control Range Setting
7.7.3. Attenuation Setting
7.8. Changing Display Units
7.9. Wavelength Offset (Calibration)
7.10. Storing Wavelength Offset & Parameter Settings
7.11. Resetting Factory Defaults
8. Communication Interfaces
8.1. GPIB Control
8.2. RS-232C Control
8.3. Control Commands
9. Example Programs
9.1. GPIB Program
9.2. RS-232C Program
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OTF-920 Operation Manual
10. Care and Maintenance
10.1. Care
10.2. Maintenance
10.3. Cleaning the Optical Connectors
10.4. Changing the Fuse
11. Troubleshooting
12. Warranty
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OPTICAL TUNABLE FILTER OTF-920
1-1
1Introduction
The OTF-920 has been designed to achieve exceptional optical performance whilst
maintaining flexibility and ease of use. t incorporates a multi-layer dielectric filter that has
been carefully fabricated to ensure high optical quality and long term stability. n addition,
the filter uses Santec’s unique linear sliding tuning technology which enables a wide tuning
range to be achieved, whilst the optical properties such as bandwidth, insertion loss, and
polarization dependent loss (PDL) are all wavelength independent.
The OTF-920 is particularly unique in that it has two optical sliders. This allows for
flexibility in configuration and operation. Each slider provides a 40nm tuning range and can
be configured with either a filter element or a variable attenuator. A combination of the two
sliders can thus provide: continuous tuning over a full 80nm, 40nm tuning but with two
separate bandwidths, or simultaneous control of wavelength and power using a combination
of filter element and attenuator in the sliders.
The OTF-920 boasts a very flexible peak search function that enables it to be used when even
multiple signals are present. This feature, combined with the GP B and RS-232C interfaces,
enable the filter to be used in a wide range of applications. The OTF-920 is easy to use, but
to obtain the most from your unit we recommend that you read this manual fully and become
familiar with its contents prior to operation. We hope that you will be satisfied with your
purchase.
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1-2
OTF-920 Operation Manual
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OPTICAL TUNABLE FILTER OTF-920
2-1
2Specifications
A wide range of filter types and a 0-20dB attenuator are available. The above table shows an
example specification using a nominal 1.2nm bandwidth (12 type), single cavity, double
stage filter in both sliders. Please see the serial number label on the rear panel for details of
the filter type and options installed on each unit.
The following items should be supplied with your OTF-920 unit:
1. 2 power switch keys
2. Power supply cable
3. Operation manual
4. Test report
Min. Typ. Max.
Filter Type -
Filter in Slider 1
Filter in Slider 2
Wavelength Range nm 1530 1610
nsertion Loss dB 2.5 3.0
Bandwidth at -3dB nm 0.9 1.0 1.1
Bandwidth at -20dB nm - 4.5 -
PDL dB - 0.1 0.2
PMD ps - - 0.1
Return Loss dB 45 50 -
Max. Optical nput Power dBm - - 20
Operating Temperature ˚C 20 - 30
Fiber Type -
Connector Type
Communication nterface -
Size mm
Weight kg
Supply Voltage V
Maximum Power W 40
100 / 110 / 230 / 240
4
210 x 80 x 300
Linear Sliding nterference Filter
Item Unit
Value
GP B, RS-232C
FC/SPC (FC/APC, SC/SPC, SC/APC options)
SMF
12-S-2: C-band, 12 Type, Single Cavity, Double Stage
12-S-2: L-band, 12 Type, Single Cavity, Double Stage
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2-2
OTF-920 Operation Manual
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OPTICAL TUNABLE FILTER OTF-920
3-1
3Features
The Peak Search function provides automatic searching and selection of the wavelength with the
greatest optical power. The function operates by sweeping the filter through a specified wavelength
range whilst continuously monitoring the optical power. On completion of the search the filter
automatically moves to the wavelength with greatest optical power. The Peak Search Function has two
modes. n the standard mode the OTF-920 sweeps through the specified wavelength range in 0.001nm
steps. A peak is thus selected with high accuracy, and by selecting a suitable scan range the function
can even be used to select a single wavelength from a comb of signals. n addition, a Rapid Mode can
also be programmed. n Rapid Mode an initial course wavelength sweep is performed at 1nm intervals
and this is followed by a fine wavelength sweep in 0.001nm steps over a range of ±1nm from the
detected peak. The Rapid Mode thus enables a rapid scan over a broad wavelength range to be
achieved whilst maintaining the high resolution and accuracy.
3.2. Peak Search Function
3.1. Wavelength Range
The OTF-920 contains two sliders in which the optical filter elements, or variable attenuator elements,
are mounted. The OTF-920 can thus be supplied in a variety of configurations. Please note that it is not
usually possible to change the configuration after manufacture. Each slider has a tuning range of 40nm
for a tunable filter and 20dB for the variable attenuator. The sliders are automatically controlled to
provide seemless wavelength tuning, or simultaneous wavelength tuning and power control. The
following combinations are possible:
•Identical filter profiles on each slider providing 80nm tuning range, e.g. 1530 - 1610nm.
•Different filter profiles on each slider, each with 40nm tuning range.
•One tunable filter and one attenuator providing both wavelength selection and power control.
Optical power monitoring is realized by tapping the optical signal using a coupler behind the filter
element and monitoring this using a photodetector. Compensation for the wavelength sensitivity of the
photodetector is carried out automatically.
3.3. Optical Power Monitor
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3-2
OTF-920 Operation Manual
The output optical power can be controlled using the variable attenuator (if fitted).The unit contains
two independent sliders; a variable attenuator can be mounted onto one of the sliders. The
attenuation can be controlled either manually or automatically. The automatic control uses an integral
closed feedback loop, using the signal from the photodetector, and provides automatic power control of
the output signal.
The OTF-920 is calibrated in the factory and should not usually require adjustment. The wavelength
calibration feature enables a user to recalibrate the unit should this become necessary. An adjustment
of up to ±1.0nm is possible. f the device requires an adjustment greater than this there may be a more
serious problem and we recommend that you contact Santec’s technical support division.
3.5. Wavelength Offset
3.4. Optical Power Control
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OPTICAL TUNABLE FILTER OTF-920
4-1
4Principle of Operation
The OTF-920 uses Santec’s unique linear sliding tuning technology. This ensures that the optical
properties of the filter, including bandwidth, insertion loss and polarization dependent loss (PDL) are
all wavelength independent. The filter element is fabricated with a wavelength gradient along its
length. Wavelength tuning is achieved by linearly sliding the filter element in the optical beam. This
tuning method ensures that the optical beam always passes perpendicularly through the filter element
and eliminates the changes in optical properties that would otherwise occur.
The OTF-920 contains two independent optical sliders. The figure above shows a schematic diagram
of this design. A tunable filter element, with a tuning range of 40nm, or a variable attenuator element,
with 20dB attenuation, can be mounted on each slider. Using tunable filters on both sliders a tuning
range of 80nm can thus achieved. The sliders are automatically controlled to provide seemless
wavelength tuning or simultaneous wavelength tuning and power control.
A small portion of the output light is tapped and monitored by a photodetector. This enables accurate
power monitoring, and when the Automatic Power Control (APC) mode is activated the signal is
processed by the CPU to provide automatic power control of the output signal.
CPU
Display
Motor
Motor
IN
PD
OUT
GPIB
RS-232C
Lens
Lens
Communication
Interface
Slider2
Slider1
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OTF-920 Operation Manual
4-2
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OPTICAL TUNABLE FILTER OTF-920
5-1
5-1. Front Panel
5Panel Descriptions
(1) Wavelength Display Panel
Displays the current wavelength setting in nm
(2) Optical Power Display Panel
Displays the optical output power. The measurement unit can be set to either mW or dBm and is
toggled by pressing the mW/dBm selector key (7). The power is calibrated according to the
wavelength setting shown in the Wavelength Display Panel (1). (Note: When the attenuator option
is fitted and the unit is operated in APC mode, the display will show the target value for automatic
power control when the PS key (28) is pressed
(3) Optical Power Unit Indicator
Indicates unit of optical output power (mW or dBm).
(4) Wavelength Unit Indicator
Indicates units of displayed wavelength (nm).
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)
(30) (29) (24) (23) (22) (21) (20) (19) (18) (17) (16) (15)
(25)
(26)
(27)
(28)
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5-2
OTF-920 Operation Manual
(5)(6) Attenuation / Wavelength Selector Key and Indicator LED (Option)
Toggles the Wavelength Display (1) between display of attenuation and wavelength. This is used
only when the attenuator option is fitted. The indicator LED shows which parameter has been
selected.
(7) Optical Power Unit Selector Key
Toggles the optical power measurement unit between mW and dBm.
(8)(9) Up / Down Arrow Key
Increments / decrements value of selected digit by one unit.
(10) Cursor Key
Allows digit selection when using Up / Down Arrow Keys to set value.
(11 ) Numeric Keypad
Allows direct input of parameters in setting modes.
(12) Clear Key (CL)
Clears values when setting.
(13) Backspace Key (BS)
Moves cursor back one space when entering parameter using numeric keypad.
(14) Enter Key (ENT)
Registers the value entered via either Up / Down Arrow Keys or Numeric Keypad.
(15) Optical Output Connector
The optical output connector is located behind a safety cover. The cover pulls down for use.
(16) Optical Input Connector
The optical input connector is located behind a safety cover. The cover pulls down for use.
(17) GPIB Local Key / GPIB Address Change Key (LOCAL)
a. Pressing this key when GPIB remote operation is active returns control to the front panel.
b. Pressing this key after pressing the SHIFT Key (22) enables the GPIB address and delimiter to be
changed. The GPIB address is first displayed in the Optical Power Display Panel (2) and can be
changed using the Up / Down Arrow Keys (8)(9). Pressing the GPIB Local Key a second time
displays the GPIB delimiter which can be similarly changed using the Up / Down Arrow Keys.
Pressing the GPIB Local Key a third time returns control to normal operation.
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OPTICAL TUNABLE FILTER OTF-920
5-3
(18) GPIB Remote LED
Indicates GPIB remote operation is active. When active the front panel keys become inoperative.
To return control to the front panel press the GPIB Local Key (17).
(19) Calibration Key (CAL)
Allows an offset to be applied to the wavelength value displayed. Also used in conjunction with
the Shift Key to remove a slider from the optical beam.
(20) Store Key
Stores the wavelength offset data to internal flash memory. This setting is then retained even
when power to the OTF-920 is switched off.
(21)(22) Shift Key with Indicator LED
Enables alternative operation of other key functions. The indicator LED lights when the Shift Key
is pressed and remains lit until a valid function key is pressed or until the Shift Key is pressed a
second time. Pressing the Shift Key a second time cancels its operation. Valid key combinations
are:
a. Shift + Local: Allows GPIB Address and Delimiter to be set.
b. Shift + PS: Sets wavelength scan range for Peak Search function.
c. Shift + APC: Sets optical power range for APC control (option).
(23)(24) Option Key with Indicator LED
Enables optional features, such as independent slider control, of the OTF-920 to be operated. The
indicator LED lights when the Option Key is pressed and remains lit until a valid function key is
pressed or until the Option Key is pressed a second time. Pressing the Option Key a second time
cancels its operation.
(25)(26) Automatic Power Control (APC) Key with Indicator LED (Option)
Turns APC control on and off. This function is only available when the attenuator option is fitted.
The indicator LED lights when APC control is active. Pressing this key after pressing the SHIFT
Key (22) enables the control range of the APC function to be set.
(27)(28) Peal Search (PS) Key with Indicator LED
1. Activates peak search function. Pressing this key during the search cancels the operation. The
LED indicates when peak search mode is active.
2. Pressing the key after pressing the SHIFT key enables the wavelength range used for the peak
search to be set.
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5-4
OTF-920 Operation Manual
(29) Serial Interface (SIF) Connector
Used for RS-232C communication.
(30) Power On / Off Key Switch
Operated using the power switch key, this is used to switch the unit on and off.
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OPTICAL TUNABLE FILTER OTF-920
5-5
5.2. Rear Panel
(1) Mains Connector Socket
(2) Fuse Housing
(3) Mains Voltage Indicator
The supply voltage is selected by removing the fuse housing cover, and rotating the mains
voltage indicator so that the correct voltage, corresponding to the mains supply voltage, is
shown in the window when the fuse housing cover is replaced. Ensure that the housing cover is
tightly closed before reconnecting the mains cord.
(4) Analogue Interface (AIF) Connector (not used)
 (1) (2) (3) (4)
(5) (6) (7)
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