|
HOME
All Fiber Doppler
Velocity Interferometer Systems
a new kind of VISAR
new extremely pure laser
Series
G Unamplified
Single Photodetectors
for light levels
of 0.1 mW and higher
Series
F Amplified Single Photodetectors
with new improved amplifiers
for light levels down to nanowatts
Series
J Amplified
Differential Photodetectors
like Series F single detectors,
but only the difference is amplified
Power
Supply
recommended
for DC coupled PDMs
and all Differentials
International
Order Policies
|
|
Martin,
Froeschner & Associates
Series G
Fast Compact Photodetector Modules
Faster, more compact, and cheaper than our Award Winning Series
99 Photodetectors.
A new line of inexpensive and compact fiber-coupled photodiode
modules simplify capturing fast transient light signals for analysis. These
devices are intended to approximate as closely as possible, a length of fiber
optic cable that can be connected directly onto the input jacks of your
oscilloscope or other electronic data acquisition device. Conversion of the
optical signal to electronic current and voltage occurs at the last possible
moment, within a mm or so of the input jacks of your scope. Co-ax cable and
the problems of reflections, termination loads, phase distortion and so forth
are totally eliminated. The devices are extremely compact and rugged, taking
up about as much room as a typical BNC terminator. They come in unamplified
versions for use when sufficient light is available, and amplified versions
for low light levels. We will build photodetector modules to your
specifications.
Dimensions: 0.65" (16mm)
diameter by 1" to 1.75" (25 to 40 mm), excluding connectors and
optical fiber
Construction: machined from solid 6061-T6 Aluminum, internal
components potted in resin
Power: internally contained, easily replaceable DL 1/3N battery.
[Back to Top]
Optical Fiber and Connector
We will build your modules with whatever optical fiber, cable and connectors
you specify. We normally stock single-mode 9/125 µm and both 50/125 µm and
62.5/125 µm multimode fiber with 0.9mm polymer buffer and 3mm Kevlar jacket.
Other types such as 100/140 µm are available. The fiber to photodiode
connection is angle polished for low (-45dB) back reflection.
The input end of the optical fiber will be fitted with whatever type of
optical fiber connector you desire. The range of normal options include:
none, i.e. a bare fiber pigtail, 2 mm ceramic ferrule only, NTT-FC, SC,
ST and SMA. The fiber end itself will be polished to any of the standard
specifications: flat, PC, SPC or APC (8o). If you need something
else, just specify so on the Order Form.
[Back to Top]
Optional Light Collecting Optics
If the signal you want to analyze is in the form of a beam in free-space we
can provide light collecting optics instead of or in addition to the optical
fiber connectors described above. A 6 mm diameter fixed focus aspheric lens
assembly is available. We also offer a micro-alignable fixture with 18 mm
aperture focusable achromatic lens. Precision fine thread adjustments allow
you to maximize the coupling of the incoming beam into the fiber. The unit is
also directly compatible with "micro-rail" optical component
systems made by Newport,
Melles-Griot, ThorLabs and others and is "C" threaded for
compatibility with Edmund Scientific's modular component line. Finally, large
aperture catadioptric systems for collecting light from weak, distended or
distant sources can be provided. Details available upon inquiry.
[Back to Top]
Photodiode Selection
 The two major
considerations in selecting the photodiode for your application are spectral
response and speed. Photodiodes based on different semiconductor materials
have, in general, different ranges of light wavelength to which they are most
sensitive.
For example, Silicon based diodes are most sensitive in the 400nm (nearly UV)
to 1000nm (near IR) spectral range and cover the visible well. InGaAs is
relatively insensitive to visible light but responds well to the IR used in
information systems.
The intrinsic speed of the photodiode is also determined by the semiconductor
material. The higher electron mobility in InGaAs allows response times which
are simply not attainable with Si. Our latest GaAs model offers unprecedented
speed in the visible range. Other factors which might be important to your
needs, such as Dark Current and Capacitance are also listed in the table on
Photodiode Specifications.
The photodiode in all our modules is reverse biased to minimize intrinsic
capacitance for maximally fast response.
[Back to Top]
Photodiode Specifications
Specifications are listed for the usual photodiodes. Others are available,
call or write for details.
|
|
GaAs
|
InGaAs-1
|
InGaAs-2
|
InGaAs-3
|
|
Spectral Range
|
450-870 nm
|
850-1700 nm
|
850-1700 nm
|
950-1650 nm
|
|
Responsivity
|
0.60 A/W at 850
|
0.9 A/W@1550
|
0.9 A/W@1550
|
0.9 A/W@1550
|
|
Bandwidth (-3db)
|
10 GHz
|
3.5 GHz
|
>7.5 GHz
|
>10 GHz
|
|
Rise/Fall Time
|
<35 ps
|
100 ps
|
<50 ps
|
<35 ps
|
|
Capacitance
|
0.2 pF
|
0.6 pF
|
0.17 pF
|
<0.2 pF
|
|
Active Area
|
75 µm dia.
|
100 µm dia.
|
50 µm dia.
|
30 µm dia.
|
|
Dark Current
|
<0.3 nA
|
<0.4 nA
|
<0.4 nA
|
<0.4 nA
|
|
Fiber Compatibility
|
up to 62.5 µm
|
up to 100 µm
|
up to 50 µm
|
single mode
|
[Back to Top]
Estimation
of Signal Level
You can estimate the signal level (voltage) that you can expect to see, for
your light intensity, directly from the Responsivity as shown in the graph
above and in the table below, from:
dV [volts] = dI [watts] • Responsivity [amps/watt] • R [ohms]
where dV is the change in output signal corresponding to a change of
dI in the light power input and R is the load resistance. The modules have an internal load
resistance of 1,000 ohms. The
effective load resistance, R, is
thus the parallel combination of this internal 1,000 ohms and any external
termination resistance such as the usual 50 ohms of an oscilloscope
input. Since the Responsivity is near
unity, in general, you will need on the order of 1 mW in the optical input
fiber in order to get output signals in the 50mV range with the Series G
modules with 50 ohm termination. You can get higher sensitivity if your scope
has a high impedance input option. In
this case the 1,000 ohm internal load resistance will dominate and the signal
levels will be twenty times higher.
Note that the bandwidth will also be reduced by this same factor of
twenty.
If you need full performance at low light levels see the Series F section.
[Back to Top]
Output Electrical Connector
Electronic output connector choices include BNC, TNC, SMA and SMC in either
gender. Wiltron-K, 7/16 and others are available at some extra cost. Please
note that BNC connectors are not recommended above 2 to 4 GHz. If you need
something really unusual, specify on your Request for Quotation or call to
discuss your needs.
[Back to Top]
Output Coupling
The output connector is directly coupled to the biased photodiode so that
these Series G modules are DC coupled.
[Back to Top]
Power Considerations
The unamplified Series G modules
have very low current drain and the small internal batteries should last for
a year or so of normal use.
[Back to Top]
Series G Photodetector Module
Summary and Prices
|
Input Optical Connector:
·
none
·
2.5mm ceramic ferrule
·
NTT-FC
·
SC
·
ST
·
SMA
·
other_______________
Polish:
·
UPC
(compatible with flat, PC, and SPC)
·
PC
·
APC 8 degrees
·
other ______________
Optical Cable:
·
9/125 µm single mode
·
50/125 µm
·
62.5/125 µm
·
other______________
Jacket:
·
0.9mm buffer only
·
3mm Kevlar and Polymer over 0.9mm buffer
·
other______________
Length:
·
1 meter (standard)
·
other_________________
Light-Collection Optics:
·
none
·
6mm fixed aspheric ($225)
·
alignable Micro-Rail and "C" thread compatible ($395)
·
Large Aperture (inquire)
|
Photodiode:
·
GaAs, 450-870nm, 10 GHz ($1,095)
·
InGaAs-1, 850-1700nm, 3.5 GHz ($795)
·
InGaAs-2, 850-1700nm, >7.5 GHz ($995)
·
InGaAs-3, 950-1650nm, >10 GHz ($1,095)
No Amplifier
Output Coupling:
·
DC coupled
Output Electronic
Connector:
·
BNC
·
TNC
·
SMA
·
SMC
·
other________
Gender:
·
male plug (as shown)
·
female jack
Power Configuration:
·
internal battery
|
[Back to Top]
How to Order
We will build your Photodetectors to your specifications. The price of your
detector is simply the sum of the prices of the chosen specified options. Email us your specifications from the list
under Summary and Prices above. We will return a formal quotation to confirm
your specifications and expected delivery time. Quantity discounts are
available, send a Request for Quotation.
Please note that these modules contain technology at the leading
edge of the state of the art. Prices and specifications are subject to
change.
Martin,
Froeschner & Associates
14300 Mines Road, Livermore, California, 94550
USA
tel: (+1)
925 989 4930
fax: (+1) 925 449 4647
email:
sales@mfaoptics.com
Last
update December 2012
©1999-2012
[Back
to Top]
|
|
Contact Us:
tel: +1 925 989 4930
fax: +1 925 449 4647
email: sales@mfaoptics.com
Martin, Froeschner & Associates
14300 Mines Road
Livermore, California
94550
USA
Papers
by Users of our FDVI
Upgrade
your FDVI
to a New
Mark IV or Mark IV-3000
System
See us in the new
Physics Today Buyer's Guide
under
VISAR
and
Photodetectors
and
our
company profile.
See us in these Buyer’s Guides:
Global
Spec
Laser
Focus World
Photonics
Spectra
|
