Click to Enlarge An illustration of the difference in the intensity noise floor between our standard FP laser sources with TEC (Item # S3FC520 shown) and our high-power FP laser sources with TEC (Item # S4FC660 shown). The noise signal from the S4FC660 shows a considerable reduction in the peak-to-peak noise amplitude, as well as suppression of high frequency components that are seen in the noise signal of the S3FC520. The S3FC520 plot is vertically offset in order to better compare the two signals. Note that the curves shown are without mode-hopping, which will occur despite temperature or current adjustment.
NIR Wavelengths Available from 705 to 2000 nm
Single Mode, FC/PC or FC/APC Fiber Interface
Typical Maximum Output Powers up to 100 mW
High-Current TEC for Temperature Regulation and Stability
BNC Connector for Modulating Output with Analog Input
USB Connector for Computer Control via Included GUI or Command Line
Power Level is Adjustable via Knob and BNC Modulation Input
Constant Current Operation
Interlock Circuit Provided via 2.5 mm Mono Jack
Thorlabs' NIR High-Power Fiber-Coupled Laser Sources are high-performance benchtop Fabry-Perot laser diode sources with TEC, which offer excellent stability and computer control. The internal electronics isolate the laser diode driver from noise coupling (such as that produced by nearby switching supplies). As a result, these high-power FP laser sources with TEC offer lower noise intensity compared to our standard FP sources with TEC (see graph to the right). The integrated, high-current TEC element can provide excellent temperature regulation and stability to the laser diode, as illustrated in the graphs on the Temp. Stability tab. Even when the ambient temperature changes significantly, the temperature control servo is capable of maintaining constant temperature at the laser diode head. This exceptional temperature stability produces a constant and stable power output from the device.
Click to Enlarge An example of the S4FC series software GUI. Both the S4FC series and S6FC2000 high-power laser sources include software packages. See the Software tab above for details.
For both the S4FC series and S6FC2000 laser sources, the laser diode is pigtailed to a single mode fiber. In the S4FC series sources, the fiber is terminated at an FC/PC bulkhead connector (wide and narrow key compatible). In the S6FC2000 source, the fiber is terminated at an FC/APC fiber connector (wide and narrow key compatible). The S6FC2000 features an angled fiber ferrule at the internal laser/fiber launch point to minimize reflections back into the laser diode, thereby increasing the stability of the laser diode's output. To minimize losses, we recommend using a fiber patch cable that is the same fiber type as the fiber-pigtailed laser.
These laser sources operate via constant current. The power is displayed on the S4FC sources, whereas the current is displayed on the S6FC2000 source. Also on the display panel is the temperature in °C, an on/off key, an enable button, a knob to adjust either the laser power (S4FC series) or the laser current (S6FC2000), and a trimpot to adjust the temperature (TEC current).
The back panel includes a BNC input that allows the laser diode drive current to be controlled via an external voltage source (0 - 5 V) and a remote interlock input. This input enables intensity modulation of the laser source. Using a sine wave, the output can obtain full-depth modulation at frequencies up to 100 kHz. A USB connector on the back panel enables computer communication. The included GUI provides control and readout of the laser's output power and setpoints (see Software tab). The back panel also features a remote interlock input (2.5 mm mono jack) for added safety.
Note that the fiber bulkhead and patch cable ferrule must be cleaned prior to connecting a patch cable. For instructions, please refer to the operating manual. The laser must be off when connecting or disconnecting fibers from the device, particularly for power levels above 10 mW. For applications that require several laser sources, consider the temperature-stabilized four-channel fiber coupled laser source.
±5% of Actual
S4FC Series Laser Adjustment Range
Laser Threshold to Max
0 mA Current to Max
S6FC2000 Laser Adjustment Range
Laser Threshold to Max or Min
0 mA Current to Max or Jumps to Min
Laser Adjustment Resolutiona
S4FC Series: 0.01 mW S6FC2000: 0.1 mA
Temperature Adjustment Range
20 °C to 30 °C
Temperature Setpoint Resolution
0 to 5 V (0 to Full Power)
Modulation Input Impedance
Modulation Input Connectorc
≤100 kHz, Sine Wave
Output Fiber Connector
FC/PC or FC/APCe, 2.2 mm Wide-Key Slot
15 to 35 °C
0 to 50 °C
85 - 264 VAC; 50 - 60 Hz
While Laser is Enabled
Modulation Input voltage directly corresponds to output power, where 5 V = Max Power and 0 V = 0 mW when the front panel knob is set to 0 mW. The maximum voltage will be less than 5 V when using the default laser adjustment range (Laser Threshold to Max).
The maximum USB and BNC cable length is 3 meters in order to avoid a susceptibility to RF interference according to IEC61000-4-3.
Waveforms other than sine waves contain components with higher frequency than the overall frequency of the waveform, which may not be followed.
Only the S6FC2000 is offered with an FC/APC connector.
Spectral plots are typical and actual spectra may vary from lot to lot. Measurements were obtained with an optical spectrum analyzer. For further information, please contact Tech Support.
Specified at Temperature Set Point of 25 °C
At 75% of maximum output power. The stability spec was obtained after a 1 hour warm-up period.
This laser source may experience mode-hopping that cannot be tuned out with temperature or current adjustment. Therefore, power stability should be interpreted as the maximum power drift over that period.
The stability data below was obtained using an S4FC660 Laser Source. The performance is representative of both our S4FC sources and our S6FC2000 source.
Click to Enlarge A demonstration of the long-term stability of the S4FC660 Laser source, shown over the course of 25 hours. The device is capable of maintaining a constant laser diode temperature, and thus constant output power, over long periods of operation. To obtain the detector signal, the S4FC660 output power was set to 75% of maximum and passed through ND filters reducing the power to 1 mW. The resultant beam was directed into a DET100A (previous generation) detector which was then connected to an oscilloscope via a T-adapter and high-impedance terminator.
Click to Enlarge The graph above demonstrates the ability of the S4FC660 to maintain steady temperature regulation even with large changes in the environmental temperature. Even when the environment changes by 20 °C, the S4FC660 is able to maintain a steady and regulated temperature of the laser diode, yielding a consistent power output. To obtain the detector signal, the S4FC660 output power was set to 75% of maximum and passed through ND filters reducing the power to 1 mW. The resultant beam was directed into a DET100A (previous generation) detector which was then connected to an oscilloscope via a T-adapter and high-impedance terminator.
0 to 5 V Max, 1 kΩ
Remote Interlock Input
2.5 mm Mono Phono Jack
Terminals must be shorted either by included plug or user device, i.e. external switch, for laser mode "ON" to be enabled.
USB Type B
S4FC Software Package
Includes a GUI for control of Thorlabs S4FC Benchtop Laser Sources. To download, click the button below.
S6FC Software Package
Includes a GUI for control of Thorlabs S6FC2000 Benchtop Laser Source. To download, click the button below.
GUI Interface Each software package allows the user to control settings and display features of the benchtop laser source. The settings tab enables several helpful features for controlling the device, including setting an output limit, starting the device from the last setting (instead of at 0 mW or threshold power), adjusting the device by current, dimming the display intensity, or enabling the temperature LED to blink when the device is not at its temperature setpoint (making it visually easier to observe when the laser is not at thermal equilibrium).
The controls tab can be used to select the temperature setpoint, interlock status, and to enable the laser's output. In the S4FC software, the power of device can be adjusted and will be displayed when the enable button is activated. In the S6FC2000 software, the current of the device can be adjusted and will be displayed when the enable button is activated.
Click to Enlarge The control panel of the software when the laser source is connected. An example of the S4FC series GUI is shown.
Click to Enlarge The Controls tab of the software when the laser source is connected and the laser not yet enabled. An example of the S6FC2000 GUI is shown.
Laser Safety and Classification
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. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. 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.
Safe Practices and Light Safety Accessories
Thorlabs recommends the use of safety eyewear whenever working with laser beams with non-negligible powers (i.e., > Class 1) since metallic tools such as screwdrivers can accidentally redirect a beam.
Laser goggles designed for specific wavelengths should be clearly available near laser setups to protect the wearer from unintentional laser reflections.
Goggles are marked with the wavelength range over which protection is afforded and the minimum optical density within that range.
Post appropriate warning signs or labels near laser setups or rooms.
Use a laser sign with a lightbox if operating Class 3R or 4 lasers (i.e., lasers requiring the use of a safety interlock).
Do not use Laser Viewing Cards in place of a proper Beam Trap.
Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:
This class of laser is safe under all conditions of normal use, including use with optical instruments for intrabeam viewing. Lasers in this class do not emit radiation at levels that may cause injury during normal operation, and therefore the maximum permissible exposure (MPE) cannot be exceeded. Class 1 lasers can also include enclosed, high-power lasers where exposure to the radiation is not possible without opening or shutting down the laser.
Class 1M lasers are safe except when used in conjunction with optical components such as telescopes and microscopes. Lasers belonging to this class emit large-diameter or divergent beams, and the MPE cannot normally be exceeded unless focusing or imaging optics are used to narrow the beam. However, if the beam is refocused, the hazard may be increased and the class may be changed accordingly.
Class 2 lasers, which are limited to 1 mW of visible continuous-wave radiation, are safe because the blink reflex will limit the exposure in the eye to 0.25 seconds. This category only applies to visible radiation (400 - 700 nm).
Because of the blink reflex, this class of laser is classified as safe as long as the beam is not viewed through optical instruments. This laser class also applies to larger-diameter or diverging laser beams.
Lasers in this class are considered safe as long as they are handled with restricted beam viewing. The MPE can be exceeded with this class of laser, however, this presents a low risk level to injury. Visible, continuous-wave lasers are limited to 5 mW of output power in this class.
Class 3B lasers are hazardous to the eye if exposed directly. However, diffuse reflections are not harmful. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. In addition, laser safety signs lightboxes should be used with lasers that require a safety interlock so that the laser cannot be used without the safety light turning on. Class-3B lasers must be equipped with a key switch and a safety interlock.
This class of laser may cause damage to the skin, and also to the eye, even from the viewing of diffuse reflections. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces. Great care must be taken when handling these lasers. They also represent a fire risk, because they may ignite combustible material. Class 4 lasers must be equipped with a key switch and a safety interlock.
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign