THORLABS SPDC810 User manual

SPDC810
Spontaneous Parametric
Down-Conversion Source
User Guide

Spontaneous Parametric Downconversion (SPDC) Source
Table of Contents
Chapter 1 Warning Symbol Definitions.............................................................................................1
Chapter 2 Safety...................................................................................................................................2
2.1. Laser Classification...................................................................................................... 2
2.2. Laser Safety Labels...................................................................................................... 2
2.3. Resources..................................................................................................................... 3
Chapter 3 Description .........................................................................................................................4
3.1. Introduction................................................................................................................... 4
3.2. Shipping List................................................................................................................. 4
3.3. Connections.................................................................................................................. 4
3.4. Operating Conditions and Environmental Requirements.......................................... 5
Chapter 4 Setup and Operation .........................................................................................................6
4.1. Before Starting.............................................................................................................. 6
4.2. Power............................................................................................................................. 6
4.3. Fiber Coupling .............................................................................................................. 6
4.4. Serial Communication.................................................................................................. 6
4.5. Operation ...................................................................................................................... 9
4.6. Lifetime.......................................................................................................................... 9
Chapter 5 Maintenance .....................................................................................................................10
5.1. Connector Cleaning.................................................................................................... 10
5.2. Alignment.................................................................................................................... 11
Chapter 6 Troubleshooting...............................................................................................................11
Chapter 7 Specifications...................................................................................................................13
Chapter 8 Mechanical Drawing........................................................................................................14
Chapter 9 Regulatory ........................................................................................................................15
Chapter 10 Declaration of Conformity ..............................................................................................16
Chapter 11 Thorlabs Worldwide Contacts........................................................................................17

Spontaneous Parametric Downconversion (SPDC) Source Chapter 1: Warning Symbol Definitions
Page 1 TTN209244-D02
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol
Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation

Spontaneous Parametric Downconversion (SPDC) Source Chapter 2: Safety
Rev B, August 20, 2020 Page 2
Chapter 2 Safety
2.1. Laser Classification
Per 21 C.F.R. §1040.10 and IEC 60825-1:2014, the SPDC810 source is classified as a Class 1 laser. The latter
form of the classification is used throughout the rest of this manual.
WARNING
Do not open the SPDC810 Source.
No access to the interior of the device is required to adjust the device or perform any maintenance
function. There are no user serviceable parts inside. Opening the device will void the warranty and
may expose you to laser light in excess of the designated laser classification.
2.2. Laser Safety Labels
Figure 1 Laser Safety Label per IEC 60825-1:2014 §7.
WARNING
Optical alignment and laser service should only be performed by qualified professionals.
WARNING
Always wear appropriate laser safety eyewear during setup and operation of the laser.
Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers.
The eye is susceptible to injury, even from very low levels of laser light. Laser emission in the visible and near
infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those
wavelengths, and the lens can focus the laser energy onto the retina.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 2: Safety
Page 3 TTN209244-D02
2.3. Resources
Safety of laser products –
Part 1: Equipment classification and requirements
IEC 60825-1:2014
ISBN 978-2-8322-1499-2
PERFORMANCE STANDARDS FOR LIGHT-EMITTING PRODUCTS
21 C.F.R. §1040
Laser Safety Guide
Laser Institute of America
ISBN 978-1-940168-03-6
www.lia.org/store/product/laser-safety-guide

Spontaneous Parametric Downconversion (SPDC) Source Chapter 3: Description
Rev B, August 20, 2020 Page 4
Chapter 3 Description
3.1. Introduction
Thorlabs’ SPDC810 is a collinear type-II Spontaneous Parametric Down-Conversion (SPDC) source. Inside, a
nonlinear crystal converts individual 405 nm photons into pairs of orthogonally polarized 810 nm photons in a single
event. These pairs are split by polarization into two channels and delivered to the two polarization maintaining (PM)
fiber outputs.
The 405 nm photons are produced by an integrated diode laser with an adjustable power of up to 150 mW. The
efficiency of the down-conversion process is approximately 10−12, leading to an output power on the order of
femtowatts.
3.2. Shipping List
SPDC810 Head
DS12 Power Supply
RS232 Cable
3.3. Connections
Figure 2 Side Panel Connections on SPDC810 Head
The SPDC810 head connections are as follows:
Left Fiber Bulkhead: “Signal”Channel
Right Fiber Bulkhead: “Idler”Channel
9-Pin D-Sub: Serial (RS232) Connection to Pump Laser
M8 Power Connection (Top Right): Connects to 12 V DC Supply

Spontaneous Parametric Downconversion (SPDC) Source Chapter 3: Description
Page 5 TTN209244-D02
3.4. Operating Conditions and Environmental Requirements
In order to achieve optimal performance of the laser system, please observe the following guidelines.
3.4.1. Temperature Range
Control of the ambient room temperature is important for stable operation of the system. The lab temperature should
be in the range of 18 °C - 25 °C.
If unpacking the device for the first time and it is extremely cold (from shipping conditions, for instance), allow it to
come to room temperature before opening the sealed internal bag. This will prevent condensation on internal optics
and damage or permanent reduction in performance.
3.4.2. Heat
The SPDC810 crystal temperature is regulated by an oven, which can produce up to 25 W of heat. Under some
conditions, the temperature of the SPDC810 housing may reach 50 °C. Make sure that there is sufficient clearance
around the device (approximately 1" on all sides) to allow airflow.
3.4.3. Air Quality and Humidity
The SPDC810 source is not hermetically sealed. Small amounts of contamination and moisture can penetrate the
enclosure. An excessively dusty or humid environment will damage the system.
The humidity should be controlled to avoid condensation and resultant damage to optical components. The system
should not be placed close to air handling vents (cooling or heating), so as to avoid sudden changes of humidity
and/or temperature.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 4: Setup and Operation
Rev B, August 20, 2020 Page 6
Chapter 4 Setup and Operation
4.1. Before Starting
All users should read and understand the safety information in this manual before operating the equipment. If
equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may
be impaired.
4.2. Power
Before connecting the power supply to the mains voltage, first connect the power supply to the device and, then,
plug in the mains power to the power supply. Communication with the device is almost immediate, but up to an hour
may be required for the device to come to thermal equilibrium.
Pin
Description
1
Not Connected
2
Not Connected
3
+12 V
4
Ground
Figure 3 Pin Descriptions for M8 Male Connector on the Housing
4.3. Fiber Coupling
Connect appropriate fiber patch cables to the output ports of the device. We recommend using the P1-780PM-FC-*
Thorlabs patch cables for maintaining polarization. If polarization information does not need to be retained,
P1-780Y-FC-* or P1-780A-FC-* cables can be used. Patch cables should be clean and free of debris before being
attached to the two output ports; see section 5.1 Connector Cleaning.
4.4. Serial Communication
The RS232 serial connection allows direct control of the integrated 405 nm pump laser.
Pin
Description
1
Data Carrier Detect (DCD)
2
Received Data (RxD)
3
Transmitted Data (TxD)
4
Data Terminal Ready (DTR)
5
Signal Ground (GND)
6
Data Set Ready (DSR)
7
Request to Send (RTS)
8
Clear to Send (CTS)
9
Ring Indicator (RI)
Figure 4 Pin Descriptions for RS232 Female Connector on the Housing
Connect a serial cable between a terminal-capable device (typically a PC) and the SPDC. Serial settings should
be:

Spontaneous Parametric Downconversion (SPDC) Source Chapter 4: Setup and Operation
Page 7 TTN209244-D02
RS232 Communication Settings
Baud Rate
115200
Data Bits
8
Stop Bits
1
Parity
None
Flow Control
XON / XOFF
Line Ending
CR-LF
Backspace
^H

Spontaneous Parametric Downconversion (SPDC) Source Chapter 4: Setup and Operation
Rev B, August 20, 2020 Page 8
4.4.1. Terminal Commands and Queries
All commands and queries are in lower case letters.
Text in [ ] is optional. To signify variables, (value, type) will be used. {Units} will be called out for reference to the
reader only, should not be included in typed commands, but may be in returned data.
Command/Query
Description
ch[annel]
1
pow[er]
(power, float)
Set pump power in mWa
di[sable]
1
Disable pumpa
echo
off
Disable echoing of characters from pump
echo
on
Enable echoing of characters from pump
en
1
Enable pump channel
id
Returns ID of pump
la[ser]
on
Activate pump diode driver
la[ser]
off
Deactivate pump diode driver
prom[pt]
off
Disable pump prompt handshake
prom[pt]
on
Enable pump prompt handshake
reset
sys
Reboot pump
sa[mple]
cur[rent]
Sample pump current continuously {mA}
sa[mple]
temp[erature]
Sample pump diode temp continuously {°C}
serial
Returns serial number of pump
sh[ow]
cur[rent]
Shows actual pump diode current
sh[ow]
limit
Returns limits of all pump settings
sh[ow]
pow[er]
Returns self-measured pump power {µW}
sh[ow]
temp[erature]
sys[tem]
Returns pump baseplate temperature {°C}
sh[ow]
temp[erature]
Returns pump diode temperature {°C}
sh[ow]
tim[er]
Returns pump & pump diode uptime {s}
sta[tus]
ch[annel]
1
Returns pump channel statusa
sta[tus]
la[ser]
Returns pump laser driver status
sta[tus]
supp[ly]
Returns pump supply voltage status
sta[tus]
temp[erature]
Returns pump driver temperature status
sta[tus]
up
Returns pump system and laser uptime
ver
Returns pump firmware version
aThe pump laser has only one channel. Using a channel number other than 1 has no effect.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 4: Setup and Operation
Page 9 TTN209244-D02
4.5. Operation
Wait for a CMD> prompt before sending commands. All commands are case-sensitive and should be lower case.
The pump power can be set before or after enabling emission. For example, to set the pump power to 10 mW,send
the following commands over the serial interface:
ch 1 pow 10
To check the current power setting:
sh pow
To turn on the pump laser and enable the pump’s channel 1, send the following commands over the serial interface:
la on
en 1
To turn the SPDC810 off:
la off
Once channel 1 has been enabled, la on and la off can be used to turn it on and off.
4.6. Lifetime
The internal 405 nm pump laser has a limited lifetime. To maximize the useful life of the SPDC810, the pump laser
should be turned off when the device is not being used. See Chapter 7 Specifications for details.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 5: Maintenance
Rev B, August 20, 2020 Page 10
Chapter 5 Maintenance
5.1. Connector Cleaning
Fiber patch cables and the connector tips inside the bulkhead connector should be cleaned every time before a
connection is made. Failure to do so may result in damage to the patch cord, the internal fiber connector, or both.
WARNING
DO NOT connect fiber patch cords to the bulkhead connectors without cleaning the fiber tips first.
Failure to follow this precaution may result in permanent damage to the unit.
Thorlabs recommends our FCC-7020 universal fiber connector cleaner (pictured below) for cleaning the tips of
patch cords. To use:
1. Open the door on top of the FCC-7020.
2. Pull the white tape out until the perforations clear the window.
3. Place the tip of the patch cord flat against the white tape on either the right or left side.
4. Drag the tip down the white tape front.
5. Repeat steps 3 - 4 on the opposite end of the patch cord.
Take care not to twist the connector while cleaning.
Instructions for using the FBC250 are located on the Thorlabs website.
FCC-7020
Fiber Cleaning Cloth Spool
FBC250
Bulkhead and Connector Cleaner
A complete line of Thorlabs’ fiber optic cleaning products can be found on the web at www.thorlabs.com.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 5: Maintenance
Page 11 TTN209244-D02
5.2. Alignment
The internal alignment of the SPDC810 is very sensitive and may become misaligned during shipping and handling.
WARNING
DO NOT OPEN THE DEVICE. DOING SO WILL VOID THE WARRANTY. IF THE DEVICE IS OPENED,
EXPOSURE TO LASER LIGHT IN EXCESS OF CLASS 1 LIMITATIONS MAY OCCUR.
Note that specialized photodetectors and electronics are required to measure the output of the SPDC810. Without
such equipment, a useful signal for alignment will not be available. Refer to the SPDC810 specifications for
information needed to choose appropriate detection equipment.
The x and y adjustments of a single internal mirror are available through access holes on the side of the SPDC810
housing (see Figure 3). The internal adjusters accept a 5/64"or 2 mm hex driver. See Chapter 8 Mechanical
Drawing for the location of these adjustors on the device housing.
Figure 5 Mirror Alignment Adjusters
Before using these adjusters, make sure that you have some coincidence signal. You should only make changes
to these adjusters when viewing the live coincidence signal rate.
The alignment precision required for time-correlated photons is significantly more challenging than the alignment
necessary to achieve uncorrelated photons in both channels. The alignment that generates the maximum correlated
photon pairs is not guaranteed to be at the exact maximum for generation of all photons (looking at each channel
in isolation).
y
x

Spontaneous Parametric Downconversion (SPDC) Source Chapter 6: Troubleshooting
Rev B, August 20, 2020 Page 12
Chapter 6 Troubleshooting
Description
Possible cause
Solution
Zero or low photons
Internal misalignment
Perform the mirror adjustment
described in 5.2 Alignment.
Low pump power
Increase the pump power.
Dirty or damaged fibers
Inspect and clean the bulkhead
connectors and patch cables.
Wavelengths of the signal and
idler channels are different
Crystal temperature has not
stabilized
Allow more time for the crystal
temperature to stabilize.
Device overheating
Ensure that the device has sufficient
room for cooling and that the ambient
temperature meets requirements.
Serial communication cannot
be established
Incorrect serial settings
Confirm RS232 settings described in
4.4.
Incorrect cabling
The provided cable is appropriate for
most RS232 scenarios. However,
non-standard configurations are
common. For other configurations,
refer to the connector diagram in
section 4.4 to help in choosing
appropriate cabling.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 7: Specifications
Page 13 TTN209244-D02
Chapter 7 Specifications
Item #
SPDC810
Operating Wavelength
810 ± 2 nm
ηsi (Detector Excluded)a,b
>0.45
Max Pairs/Second
>450 kHz
Wavelength Stabilitya
±2.5 nm
Temperature Control
No
g(2)(τ= 0)a,c
<0.1
Extinction Ratioa
>17 dB
Lifetime
>2500 Hours of Pump Emission
Pump Laser Powerd
10 mW to 150 mW
User Serviceable
No
Input Voltage
100 - 240 V
Frequency
50 - 60 Hz
Power Consumption
25 W (Max)
Interface
RS232 Serial
Room Temperature
18 °C to 25 °C
Storage Temperature
-10 °C to 60 °C
Humidity
Non-Condensing
Dimensions ( L x W x H )
10.13" x 6.41" x 2.24"
(257.2 mm x 162.7 mm x 56.9 mm)
Weight
2.6 kg
a. For a Pump Laser Power of 35 mW
b. is the heralding ratio and can be determined using 
, where C respresents the
coincidence counts and Psand Piare the raw counts on the signal and idler channels,
respectively.
c. Second-Order Correlation Measurement at Zero Time Delay
1
d. The SPDC810 can be used at lower pump powers, but specifications will not be met.
1
More information can be found in P. Granger, G. Roger, and A.Aspect, “Experimental Evidence for a Photon Anticorrection Effect on a Beam
Splitter: A New Light on Single-Photon Interference,” Europhysics Letters, vol. 1, no. 4, pp. 173, 1985.

Spontaneous Parametric Downconversion (SPDC) Source Chapter 8: Mechanical Drawing
Rev B, August 20, 2020 Page 14
Chapter 8 Mechanical Drawing
Figure 6 Mechanical Drawing of the SPDC810 Photon-Pair Source

Spontaneous Parametric Downconversion (SPDC) Source Chapter 9: Regulatory
Page 15 TTN209244-D02
Chapter 9 Regulatory
As required by the WEEE (Waste Electrical and Electronic Equipment Directive) of the European Community and
the corresponding national laws, Thorlabs offers all end users in the EC the possibility to return “end of life” units
without incurring disposal charges.
This offer is valid for Thorlabs electrical and electronic equipment:
Sold after August 13, 2005
Marked correspondingly with the crossed out “wheelie bin” logo (see right)
Sold to a company or institute within the EC
Currently owned by a company or institute within the EC
Still complete, not disassembled and not contaminated
As the WEEE directive applies to self-contained operational electrical and electronic products, this end of life take
back service does not refer to other Thorlabs products, such as:
Pure OEM products, that means assemblies to be built into a unit by the user (e. g. OEM laser driver cards)
Components
Mechanics and optics
Left over parts of units disassembled by the user (PCB’s, housings etc.).
If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs or your nearest dealer for further
information.
Waste Treatment is Your Own Responsibility
If you do not return an “end of life” unit to Thorlabs, you must hand it to a company specialized in waste recovery.
Do not dispose of the unit in a litter bin or at a public waste disposal site.
Ecological Background
It is well known that WEEE pollutes the environment by releasing toxic products during decomposition. The aim of
the European RoHS directive is to reduce the content of toxic substances in electronic products in the future.
The intent of the WEEE directive is to enforce the recycling of WEEE. A controlled recycling of end of life products
will thereby avoid negative impacts on the environment.
Wheelie Bin Logo

Spontaneous Parametric Downconversion (SPDC) Source Chapter 10: Declaration of Conformity
Rev B, August 20, 2020 Page 16
Chapter 10 Declaration of Conformity