Micron Optics FFP-TF2 User manual

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 1
Fiber Fabry-Perot Tunable Filter | FFP-TF2
First Time User Manual
Micron Optics Inc.
1852 Century Place NE
Atlanta, GA 30345 USA
phone [phone]
fax [phone]
www.micronoptics.com

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 2
Congratulations on the purchase of your Micron Optics tunable filter. Our patented,
high performance filter incorporates the highest optical and mechanical resolution
available while maintaining the most reliable all-fiber platform.
This document was prepared for first-time users of the FFP-TF2. Additional critical
information can be found online at www.micronoptics.com.
As a first time user, you should find this handbook valuable in helping you get the
most out of your filter as soon as possible. System designers requiring a more in-
depth understanding of filter operation and characteristics may find our “FFP-TF2
Technical Reference”helpful. This document is also available online at our website.
All of us at Micron Optics thank you for purchasing our products.

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 3
GETTING STARTED
(1) Carefully unpack the filter from the special shipping case, taking extra
care to avoid breaking the optical fiber (fig. 1). NOTE: the filter is shipped with a
loose-tube jacket to provide added protection to the fiber pigtails. Pulling on the fiber while holding onto the
jacket can break the fiber inside the filter enclosure and destroy the filter. Always wrap several coils of the
pigtail around a 1-inch diameter mandrel to strain relief the fiber before stripping the buffer from the ends of
the fiber.
Figure 1 Tunable filter packed in special shipping case.
(2) Carefully remove the shorting wire from the actuator terminals.
(3) Unpack the FFP-C controller and follow these quick-setup directions:
(a) Verify that the supply voltage selector on the rear panel is correct for
your local voltage.
Figure 2. Power supply voltage selector, power cord connection, and on/off switch.
(b) Turn the SCAN AMPLITUDE and the SCAN FREQUENCY knobs fully
counterclockwise.
Optical fiber

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 4
Figure 3. FFP-C front panel.
(c) Plug the AC power cord into the rear panel of the FFP-C unit and turn
the power on.
(d) Connect the FFP cable to the controller. Attach the red clip lead to the
(+) terminal and the black lead to the (-) terminal.
WARNING: Reversing the polarity can permanently damage
the FFP filter!
Figure 4. FFP-C controller.

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 5
Typical Oscilloscope Configuration
(1) Connect the FFP-C PZT, Test, and Sync output BNC connections to your
oscilloscope channels 1, 2, and external trigger respectively.
Figure 5. FFP-C rear panel.
(2) Set oscilloscope channel 1 (PZT) sensitivity to 5 or 10 volts per division. Set
channel 2 (Test) sensitivity to 0.1 volts per division. Set the sweep to 1
millisecond per division. Set the trigger source (Sync) to external and set the
slope to +.
(3) Insert the filter into the optical path, as shown on the next page. Note: Input
and Output isolation may be required to prevent optical reflection
instabilities.
To channel 2 To external
trigger input
To channel 1

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 6
Typical Optical Configuration
Cou
p
ler
O
p
tical Source Output
Photo-detector
Input

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 7
Note: This is a representative oscilloscope display of the scan voltage and the
corresponding filter response.

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 8
Modes of Operation: Manual vs. Scan vs. Dither
The tunable filter and controller can operate in one of three modes: (1) Manual, (2)
Scan, and (3) Dither (or locked). In Manual mode, the amplitude and frequency
knobs are turned completely counter-clockwise. The offset knob adjusts the DC
voltage applied to the filter PZT actuator, thereby adjusting the resonance
wavelength in the Fabry-Perot cavity.
In Scan mode, the FFP-C supplies a simple triangular voltage waveform output to
the FFP connection. The triangular wave amplitude can be adjusted from zero to
>50 volts peak to peak. The frequency of the triangular wave can be adjusted from
20 to 100 Hz. The DC offset can be adjusted from less than 5 volts, to over 50
volts. We recommend setting the Offset to 30 volts (the center of the controller
supply voltage range). Scan mode is used primarily for sweeping the filter through a
range of wavelengths for applications such as (un-calibrated) optical spectrum
analysis and WDM channel equalization monitoring. Either the internal photo-
detector or an external photo-detector can be used to monitor the filtered optical
signal in Scan mode.
Dither (locked) mode, on the other hand, requires using the internal FFP-C photo-
detector input for closed loop operation. Dither mode is utilized for locking the FFP-
TF or the FFP-SI to a particular narrow line source, and is required to achieve
optimum tuning stability and to compensate for electrical, thermal, and mechanical
variations in the FFP-TF and the input light source. In Dither mode, the controller
supplies a low-voltage 2 KHz dither frequency to the FFP device for optimum error
correction within the feedback loop. Note that the feedback circuit was designed
for slowly varying wavelength shifts due to thermal drift in both the source and the
filter.
Note: The controller is not designed to operate in the dither (locked) mode with
high Finesse (> 750) filters.

Fiber Fabry-Perot Tunable Filter | FFP-TF2
Copyright © 2009 Micron Optics, Inc. First Time User Manual 9
Frequently asked questions and answers
(Q.1) What is the recommended Maximum Drive Voltage for the filter?
(A.1) As the voltage on the PZT increases, the PZT expands causing the optics to
move closer together. It is important that the filter drive voltage remain below 70
volts to ensure that the optics are not damaged.
(Q.2) What is the recommended Maximum Drive Frequency for the filter?
(A.2) To avoid overheating the PZT, and to avoid complex compensation and
dampening circuitry, we recommend that the filter be driven at less than 300 Hz if
using the complete voltage range (0 –50 volts). A higher drive frequency can be
utilized if the drive voltage is reduced.
(Q.3) How do I eliminate optical instabilities due to reflections from the FFP-TF?
(A.3) Place an optical isolator between the laser and the FFP-TF to avoid reflection
instabilities in the light source. Recall that all out-of-band (non resonant) energy is
reflected back to the source and can damage a laser if not properly isolated. An
isolator may also be required after the filter to eliminate down-stream reflection.
(Q.4) How much optical power can the FFP-TF2 handle without damage?
(A.4) Our Finesse-200 filters have been tested to 200 mW (23 dBm) in band of average
power without any damage to the optical coatings. Since the damage threshold scales
inversely with finesse rating of the filter; the lower finesse filters can withstand higher
optical power.
For more information on this or any other Micron Optics product, please contact us
at:
Micron Optics, Inc.
1852 Century Place, NE
Atlanta, Georgia 30345
Phone: [phone]
Fax: [phone]
Email: [email protected]
Web: www.micronoptics.com