Pigtailed Laser Diode Mount

  • Mounts Thorlabs’ Pigtailed LDs
  • Compact Housing Protects Pigtail
  • Integrated Thermistor and TEC


Application Idea

LDM9LP with Mounted
Pigtail Laser Diode

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LDM9LP Disassembled with Pigtailed LD
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The LDM9LP with Mounted Pigtailed LD and the Cover and Clamshell Removed
LDM9LP Disassembled with Pigtailed LD
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Front (Top) and Back (Bottom) Images of the LDM9LP Circuit Board


  • Designed for Thorlabs' SM, PM, MM, and DFB Pigtailed Laser Diodesa (Ø5.6 or Ø9 mm, 3 or 4 Pin)
  • Supports A, B, C, D, E, G, and H Pin Configurations
  • TEC Element Prolongs LD Life and Stabilizes Output Power & Wavelength
  • Clamshell Design Eliminates Thermal Gradients Across Diode
  • Bias-T Adapter for RF Modulation of Laser Current >200 kHz
LDM9LP Disassembled with Pigtailed LD
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Close Up of Mounted Pigtail LD in LDM9LP Mount

Thorlabs' LDM9LP is an LD and TEC mount designed for use with our 3- and 4-pin pigtailed diodesa. The compact housing protects the pigtail from physical damage, while also offering excellent thermal characteristics. When operating a pigtailed laser diode, temperature control is highly recommended to stabilize the laser's power and wavelength, while also prolonging the life of the laser. Typical laser diode mounts rely on contact between the diode and the mount's cold plate for heat transfer. Pigtailed laser diodes are often recessed in the pigtail's housing, offering poor contact with the cold plate of standard laser diode mounts. The LDM9LP, however, is specifically designed for operating pigtailed laser diodes. Its clamshell design reduces thermal gradients across the diode, while its cold block cradles the pigtail housing for excellent contact and heat transfer. Performance can be further improved by using thermal grease around the pigtail package within the clamshell.

The LDM9LP allows the user to quickly and easily install or remove pigtail diodes from the mount. The back of the curcuit board contains a jumper for selecting the appropriate pin configuration of the laser diode (see image to the right). The jumper is labeled with the compatible pin codes for easy reference. Before installing the pigtailed LD, ensure that the jumper is set correctly. Additionally, the front for the circuit board is labeled with a pinout for the socket to help orient the laser diode correctly before mounting (see Mounting Instruction tab for more detail).

Two 1/4" through holes can be used for securing the mount to an optical table with 1/4"-20 or M6 cap screws. It is highly recommended prior to mounting the diode that users verify the diode pin configuration to ensure the laser diode drive pin is secured in the correct socket. Both the inside of the cover and the front of the circuit board contain the pinout for the socket.

DB9 connections interface with all of Thorlabs' LD Current Controllers and TEC Controllers. An RF SMA connector allows access to a Bias-T circuit for RF modulation of the laser's drive current (>200 kHz). For modulation below 200 kHz, current should be modulated through the laser diode controller. A remote interlock jack is provided for the connection of safety devices such as shutters and warning signs.

a. Due to the variety of fiber pigtailed laser diode packages offered by other companies, this mount is only designed for use with Thorlabs products. The mount can also be used with our VHG-stabilized pigtailed laser diode without the protective cover installed; this should not affect diode performance. Thorlabs offers a laser diode pigtailing service; please contact Tech Support for details.

LDM9LP Specifications
Laser Diode Package Thorlabs' SM, PM, MM, and DFB Pigtailed Laser Diodes
(Ø5.6 or Ø9 mm, 3 or 4 Pin)
Supported Pin Configurations A, B, C, D, E, G, & H
Laser Current (Max) 1 A
Laser Diode Polarity Selectable
Monitor Diode Polarity Selectable
LD Interface DB9, Female
RF Power (Max) 500 mW
RF Input Impedence 50 Ω
Modulation Frequency (Bias-T) >200 kHz
RF Input Connector SMA
TEC Current (Max) 4.5 A
TEC Voltage (Max) 3.0 V
TEC Heating/ Cooling Capacity 7 W (Mounted to a 12" × 12" Breadboard)
TEC Interface DB9, Male
Temperature Sensor 10 kΩ Thermistor, ±1% at 25°C, β = 3988
Typical Temperature Range (LD Dependent) 0 to 70 °C
-10 to 70 °C (Mounted to a 12" × 12" Breadboard)
Remote Interlock 2.5 mm Phono Jack
Dimensions (L × W × H) 4.48" × 3.5" × 2.1"
(113.8 mm × 88.9 mm × 53.3 mm)

Supported Pin Configurations: A, B, C, D, E, and H; Unsupported Pin Configurations: F and G

A list of the supported pin configurations can be found on the underside of the LDM9LP's cover.

Settings for Supported Laser Diode Pin Types

The LDM9LP is compatible with A, B, C, D, E, and G pin configurations. The drawing below illustrates how each pin code should be aligned with the socket on the laser mounting PCB. Two jumper pins, shown in the photo to the lower right, also need to be set. Settings are outlined in the table below. The BYPASS jumper should be set only if the laser is modulated via the LD Driver input.

LDM9LP Accepted Pins
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The pin diagrams above show how the laser diode pins should align with the socket on the laser mounting PCB.
LDM9LP Jumper Pins
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The image above shows the locations of the STYLE and BYPASS jumper pins. The STYLE jumper pin needs to be set for the pin style of the laser diode in use. The BYPASS jumper should only be set if the laser is modulated via the LD Driver input. Settings are outlined in the tables below.
STYLE Jumper
Laser Diode Pin Jumper Position
A, B, C, D, E, or H Lower 2 Pins
G Upper 2 Pins
BYPASS Jumpera
Operation Mode Jumper Position
Low Noise, No Modulation Removed
RF Modulation via RF IN (BIAS-T) Removed
Modulation via LD Driver Inputb Set
  • The BYPASS jumper should be set only if the laser is modulated via the LD Driver input.
  • If the LD Driver being used has a noise reduction filter feature, the jumper may need to be removed to ensure good performance. If modulating via the CLD1010LP or CLD1011LP, the noise reduction filter on the driver must be turned off.

Laser Diode Connector

D-type Female

DB9 Female

Pin #Signal
1Interlock and Status Pin (LDC Specific)
2Photodiode Cathode
3Laser Ground (Case)
4Photodiode Anode
5Interlock and Status Return
6Laser Diode Voltage (-)
7Laser Diode Cathode
8Laser Diode Anode
9Laser Diode Voltage (+)

TEC Connector

D-type Male

DB9 Male

Pin #Signal
1TEC Lockout (+)
5-TEC and TEC Lockout (-)
6Not Connected
7Not Connected
8Not Connected
9Not Connected

Laser Diode Socket

LD Socket

G - Ground
LD - Laser Diode Pin
PD - Photodiode Pin

RF Modulation

SMA Female

SMA Female

This is a 50 Ω input that is AC-coupled directly to the laser through the Bias-T network for modulation frequencies >200 kHz.

Polarization Window, Straight vs. Coiled
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The graph above shows the RF modulation response of the LDM9LP when modulated through an external controller. The LDC202C benchtop LD current controller was used to produce the data shown above.

Polarization Window, Straight vs. Coiled
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The graph above shows the RF modulation response of the LDM9LP when modulated through the onboard Bias-T SMA input.

Laser Diode Mount
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Step 1: Using a 1.5 mm hex key (included with mount) or balldriver, remove the screws from the cover.
Laser Diode Mount
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Step 2: Using a 1.5 mm balldriver or hex key, remove the four screws securing the clamshell.
Hysteresis Loop of Piezoelectric Actuator
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Step 3: Finally, remove the two 1.5 mm hex screws that secure the circuit board.
Laser diode Mount
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Step 4: Gently pull the circuit board up, removing it from its socket. Before mounting a laser diode to the board, ensure that the jumpers on the back have been correctly set (see the Specs tab for more information).
Laser Diode Mount
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Step 5: Install the LD into the socket, using the pinout on the circuit board to correctly align the LD's pins (see the pin configuration diagram on the Specs tab). Be sure to use a grounding strap (such as the WS01 or WS02) whenever handling LDs.
Laser Diode Mount
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Step 6: With the diode mounted, carfully plug the circuit board back into its socket. When firmly seated, secure with the two hex screws removed in step 3.
Laser Diode Mount
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Step 7: Replace all four screws removed in step 2. Be sure to snug up all the screws to ensure proper thermal contact.
Laser Diode Mount
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Step 8: Replace the screws holding the cover onto the mount.
Laser Diode Mount
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Step 9: Finally, secure the LDM9LP to a breadboard or optical table with 2 1/4"-20 (M6) cap screws.
LDM9LP SmartPack Packaging
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LDM9LP Packaging

Smart Pack

Item #% Weight
LDM9LP 14.71% 5.26 kg

Smart Pack

  • Reduce Weight of Packaging Materials
  • Increase Usage of Recyclable Packing Materials
  • Improve Packing Integrity
  • Decrease Shipping Costs

Thorlabs' Smart Pack Initiative is aimed at waste minimization while still maintaining adequate protection for our products. By eliminating any unnecessary packaging, implementing packaging design changes, and utilizing eco-friendly packaging materials for our customers when possible, this initiative seeks to improve the environmental impact of our product packaging. Products listed above are now shipped in re-engineered packaging that minimizes the weight and the use of non-recyclable materials.b As we move through our product line, we will indicate re-engineered packages with our Smart Pack logo.

  • Travel-based emissions reduction calculations are estimated based on the total weight reduction of packaging materials used for all of 2013’s product sales, traveling 1,000 miles on an airplane, to provide general understanding of the impact of packaging material reduction. Calculations were made using the EPA’s shipping emissions values for different modes of transport.
  • Some Smart Pack products may show a negative weight reduction percentage as the substitution of greener packaging materials, such as the Greenwrap, at times slightly increases the weight of the product packaging.

Posted Comments:
Adriana Riofrio  (posted 2021-07-24 23:19:14.763)
Good evening, we have purchased the LDM9LP but we want to use a controller from another manufacturer (arroyo instruments). We have worked out the current and temperature control wire but we have a 501 message related to the interlock. The 2.5 mm Mono Phono Jack did not come to us, is it necessary to connect it with an external voltage source at 5V? Could you tell me how the circuit should look? I appreciate your response
cdolbashian  (posted 2021-08-19 01:57:47.0)
Thank you for contacting us here at Thorlabs! It seems like you are simply missing the interlock pin for your device. I have reached out to you directly to resolve this.
Chad Bender  (posted 2020-08-27 16:48:43.677)
I am trying to bring back into service an old ITC502 controller. The pinout for the controller LD Driver DB9 appears to match the current pinout for the LDM9LP. However, the TEC has clearly changed in the past decade (controller has a DB15). Does Thorlabs provide a cable that can connect these devices, or will I need to fabricate a custom cable? I can certainly do that - would just prefer to save time if I can buy an COTS cable.
MKiess  (posted 2020-08-31 06:55:16.0)
Hello Chad, thank you for your inquiry. The cables that came with the ITC502 are also compatible with the LDM0LP. The pin configurations of the newer controllers are the same as the ITC502. The matching cables would be the CAB400 for the laser controller and the CAB420-15 for the temperature controller. These cables are still available on our website.
Hosung Byun  (posted 2020-05-30 01:31:28.05)
Hello, Thorlab! This is Hosung Byun, graduated student at Seoul National University in Korea. I bought 'LDM9LP Mount' to operate 'LP635-SF8' diode laser. And I try to use LDC220C & TED200C for drivers, which are fully functional to LDM56/M. But I found that TED200C can not detect the sensor, indicating 'no sensor', while LDC220C works. So I want to know whether TED200C is not compatible to LDM9LP, although it is written "All Thorlabs TED series temperature controllers" in manual. If not, let me know expected reasons for this and solutions, or I would like to exchange it. Thank you. Kind regards, Hosung Byun.
asundararaj  (posted 2020-06-01 03:04:56.0)
Thank you for contacting Thorlabs. The TED200C is compatible with the LDM9LP. Typically, the "NO SENSOR" message would indicate that the temperature sensor is incorrectly selected or not connected. The temperature sensor in the LDM9LP is a 10 kΩ Thermistor. I have contacted you directly to assist further.
Hugh Wilson  (posted 2019-04-03 22:09:52.347)
Hello, I would like to ask about the pink/grey pads of material placed in the inside of the clamshell of the LDM9LP (visible in step 3 of the mounting instructions: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=4839&pn=LDM9LP) Do they have any function or should they be removed prior to applying thermal paste and mounting the diode? Thank you very much for your help. Best, Hugh
YLohia  (posted 2019-04-08 03:09:19.0)
Hello Hugh, thank you for contacting Thorlabs. This is a thermally conductive pad and is meant to maximize the thermal contact in place of thermal grease. It’s a bit cleaner to use than thermal grease since the connection is designed to be user-serviceable. That being said, you may remove the pad prior to applying thermal grease if it looks like your application produces a high heat load.
Bernard Alunda  (posted 2019-03-16 12:45:01.73)
Hello, I have a question regarding the laser diode mount LDM9LP. In chapter of the manual, section about RF modulation, what does the "Use the laser controller to establish the DC operating point of the laser"? I am using LDC501 to drive the laser. Please let me know. Thank you and hoping to hear from you soonest. Warmest Regards, Ben
llamb  (posted 2019-03-28 09:01:54.0)
Hello Ben, thank you for your feedback. That sentence in the manual refers to establishing a center point around which you will be modulating, a point above the laser threshold value in most cases. I have reached out to you directly for any further clarification.
jlow  (posted 2012-08-03 16:47:00.0)
Response from Jeremy at Thorlabs to Hazen: To mount the pigtail on this, one would set the pigtail down on the bottom copper plate first before slowly trying to get the pins to slide in (mostly done by feel). While this is do-able (but definitely not ideal), the steep viewing angle does make it quite difficult to mount our pigtail in an easy way, which means this would warrant a redesign of the mounting part. We would certainly welcome any additional feedback you are willing to share with us. I will let our engineering group know about this and get started on ideas on improving this mount.
hbabcock  (posted 2012-08-03 15:31:02.0)
These work well once you manage to get your diode mounted. However in my experience getting your diode in position is a lot more difficult than one would hope. I have on several occasions managed to almost destroy the pins on the diode trying to get them lined up & inserted into the mounting socket. It might be easier if the brass/copper bottom plate was also removable so that you were not forced to come in at such a steep angle? -Hazen Babcock
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LDM9LP Support Documentation
LDM9LPLD/TEC Mount for Thorlabs Fiber-Pigtailed Laser Diodes
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