Distributed Feedback QCLs on D-Mounts

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Features

• Single-Wavelength Distributed Feedback Quantum Cascade Lasers (QCLs)
• Compact D-Mount (12.0 mm × 4.5 mm × 2.8 mm) Fits into Small Assemblies
• Center Wavelength in 7.00 - 8.00 µm Range (1429 - 1250 cm^-1)
• Output Can Be Tuned over 1 - 2 cm^-1 Range
• Typical CW Output Power of 100 mW
• Built-In Thermistor for Chip Temperature Measurements
• Used in Chemical Analysis, Sensing, and IR Countermeasures
• Custom Packages and Wavelengths from 3 to 12 µm Available

Designed for OEM customers, Thorlabs' D-Mount Distributed Feedback Quantum Cascade Lasers (QCLs) are our most compact mid-IR lasers. Like our D-mount FP lasers, which feature a cavity length of either 6.0 mm or 7.5 mm, this D-mount DFB laser has an emission height of 2.6 mm, as measured from the bottom of the D-mount, but feature a 4.5 mm cavity length. The copper tungsten D-mount provides high thermal conductivity for heat dissipation and is machined with two 1.4 mm wide open counterbored slots for mounting, conserving space in situations where it is at a premium.

The drive voltage and current are supplied via two large gold contact pads, which are suitable for wire bonding or probe connections. Each laser is electrically isolated from its D-mount. A built-in thermistor provides real-time temperature measurements for the control electronics. Heat loads for these lasers can be up to 7.2 W, so they must be mounted in a thermally conductive housing to prevent heat buildup. Please see the Handling tab for more tips and information for handling this laser package.

Distributed Feedback QCLs emit at a well defined center wavelength and provide single transverse mode operation. By tuning the input current and operating temperature, the output frequency can be tuned over a narrow range of 1 - 2 cm^-1. These lasers are ideal for chemical sensing and sample analysis applications. Before shipment, the output spectrum, optical power, and L-I-V curve are measured for each serial-numbered device by an automated test station. These measurements are available below and are also included on a data sheet with the laser.

Each D-mount QCL has an uncoated back facet and an uncoated or AR-coated front facet (see the Appearance tab for details). These QCLs are specified for CW output. While pulsed output is possible, this application prohibits current tuning, and performance is not guaranteed. These lasers do not have built-in monitor photodiodes and therefore cannot be operated in constant power mode.

For industrial and academic research, Thorlabs manufactures Distributed Feedback and Fabry-Perot Quantum Cascade Lasers that are mounted on two-tab C-mount packages. These packages provide easier handling than D-mounts and can be interfaced to our SM1 lens tubes, 30 mm cage systems, and 60 mm cage systems using the LDMC20 C-Mount Laser Mount.

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Available Wavelengths for Custom DFB Lasers

DFB QCLs at Custom Wavelengths

Thorlabs manufactures custom and OEM quantum cascade lasers in high volumes. We maintain chip inventory from 3 µm to 12 µm at our Jessup, Maryland, laser manufacturing facility and can deliver DFB lasers with custom center wavelengths that are qualified to a user-defined wavelength precision.

More details are available on the Custom & OEM Lasers tab. To inquire about pricing and availability, please contact us. A semiconductor specialist will contact you within 24 hours or the next business day.

Current and Temperature Controllers

Use Tables 2.1 and 2.2 to select a compatible controller for our MIR lasers. Table 2.1 lists the controllers with which a particular MIR laser is compatible, and Table 2.2 contains selected information on each controller. Complete information on each controller is available in its full web presentation. We particularly recommend our ITC4002QCL and ITC4005QCL controllers, which have high compliance voltages of 17 V and 20 V, respectively. Together, these drivers support the current and voltage requirements of our entire line of Mid-IR Lasers. To get L-I-V and spectral measurements of a specific, serial-numbered device, click "Choose Item" next to the part number below, then click on the Docs Icon next to the serial number of the device.

Handling D-Mount Lasers

Proper precautions must be taken when handling and using D-mount lasers. Otherwise, permanent damage to the device will occur. Members of our Technical Support staff are available to discuss possible operation issues.

Avoid Static
Since these lasers are sensitive to electrostatic shock, they should always be handled using standard static avoidance practices.

Avoid Dust and Other Particulates
Unlike TO can and butterfly packages, the laser chip of a D-mount laser is exposed to air; hence, there is no protection for the delicate laser chip. Contamination of the laser facets must be avoided. Do not blow on the laser or expose it to smoke, dust, oils, or adhesive films. The laser facet is particularly sensitive to dust accumulation. During standard operation, dust can burn onto this facet, which will lead to premature degradation of the laser. If operating a D-mount laser for long periods of time outside a cleanroom, it should be sealed in a container to prevent dust accumulation.

Use a Current Source Specifically Designed for Lasers
These lasers should always be used with a high-quality constant current driver specifically designed for use with lasers, such as any current controller listed in the Drivers tab. Lab-grade power supplies will not provide the low current noise required for stable operation, nor will they prevent current spikes that result in immediate and permanent damage.

Thermally Regulate the Laser
Temperature regulation is required to operate the laser for any amount of time. The temperature regulation apparatus should be rated to dissipate the maximum heat load that can be drawn by the laser. For our QD7500DM1 laser, this value is 7.2 W.

The bottom face of the D-mount package is machined flat to make proper thermal contact with a heat sink. Ideally, the heat sink will be actively regulated to ensure proper heat conduction. A Thermoelectric Cooler (TEC) is well suited for this task and can easily be incorporated into any standard PID controller.

A fan may serve to move the heat away from the TEC and prevent thermal runaway. However, the fan should not blow air on or at the laser itself. Water cooling methods may also be employed for temperature regulation. Do not use thermal grease with this package, as it can creep, eventually contaminating the laser facet. Pyrolytic graphite is an acceptable alternative to thermal grease for these packages.

For assistance in picking a suitable temperature controller for your application, please contact Tech Support.

Carefully Make Electrical Connections
When making electrical connections, care must be taken. For D-mount lasers, solder should never be used; wire bonding or probe connections are the only recommended methods.

Minimize Physical Handling
As any interaction with the package carries the risk of contamination and damage, any movement of the laser should be planned in advance and carefully carried out. It is important to avoid mechanical shocks. Dropping the laser package from any height can cause the unit to permanently fail.

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Figure 4.1  D-Mount Laser with Uncoated Front Facet (Left) and AR-Coated Front Facet (Right)

Appearance

In order to ensure that the finished lasers meet their target specifications, they are qualified by an automated test station before shipment. The test station measures the output spectrum, optical power, and L-I-V curve, which are included on a data sheet that ships with each serial-numbered laser. These measurements are also available below by clicking "Choose Item" and then clicking on the red Docs icon () that appears.

Because every laser is a unique device, certain units require the front facet to receive an anti-reflection (AR) coating to reach the specified output power. As a result, finished units will have varying appearances, as shown by Figure 4.1. These cosmetic differences do not affect the performance of the laser when it is operated within its specified parameters. All shipped units have been burned in and have passed our rigorous optical performance, reliability, and environmental testing.