Features

• Standard Available Wavelengths: 635 nm, 675 nm, 780 nm, 1310 nm, and 1550 nm
• Custom Wavelengths Available
• Single Mode FC/PC Fiber Interface
• Low Noise, Stable Output
• Interlock Input

The S1FC Series Fiber-Coupled Laser Sources conveniently package a pigtailed FP laser diode and current controller into a single benchtop unit. The Fabry-Perot laser diode inside each unit is pigtailed to a single mode fiber that is terminated at an FC/PC bulkhead (wide 2.1 mm key compatible) attached to the front panel of the unit. See the Specs tab for a list of compatible single mode fiber optic patch cables.

Also found on the front panel is a display that shows the output power in mW, an on / off key, an enable button, and a knob to adjust the laser power. The back panel includes an input that allows the laser diode drive current to be controlled via an external voltage source and a remote interlock input. All of our fiber-pigtailed lasers utilize 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.

For applications using a 635 nm or 1550 nm source, Thorlabs also offers a compact fiber coupled laser source with a USB interface. For a polarized output, laser sources that incorporate polarization-maintaining fiber are also available for many of the same output wavelengths. A 473 nm benchtop laser source that incorporates multimode fiber is also available.

S1FC Series Fabry-Perot Laser Specifications

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
• Laser Barriers and Blackout Materials can prevent direct or reflected light from leaving the experimental setup area.
• Thorlabs' Enclosure Systems can be used to contain optical setups to isolate or minimize laser hazards.
• All beams should be terminated at the edge of the table, and laboratory doors should be closed whenever a laser is in use.
• Do not place laser beams at eye level.
• Carry out experiments on an optical table such that all laser beams travel horizontally.
• Remove unnecessary reflective items such as reflective jewelry (e.g., rings, watches, etc.) while working near the beam path.
• Be aware that lenses and other optical devices may reflect a portion of the incident beam from the front or rear surface.
• Operate a laser at the minimum power necessary for any operation.
• If possible, reduce the output power of a laser during alignment procedures.
• Use beam shutters and filters to reduce the beam power.
• Post appropriate warning signs or labels near laser setups or rooms.
• Use laser sign lightboxes 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 Laser Barrier or Beam Trap.

Laser Classification

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:

Class	Description	Warning Label
1	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.
1M	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.
2	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).
2M	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.
3R	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.
3B	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.
4	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

S3FC Fabry-Perot Series Features

• Standard Available Wavelengths: 405 nm, 473 nm, and 488 nm
• Custom Wavelengths Available
• Thermo-Electric Temperature Stabilization
• Adjustable Temperature Set Point
• Adjustable Power
• Interlock Input

The S3FC series of single channel benchtop lasers have an integrated TEC element that is used to stabilize the temperature of the FP laser diode, which in turn stabilizes the output power and wavelength of the laser diode for a given drive current. The FP laser diode is pigtailed to a single mode fiber that is terminated at an FC/PC bulkhead connector (wide 2.1 mm key compatible) on the front panel. Also found on the front panel is a display that selectably shows either the output power in mW or the temperature in °C, a on / off key, an enable button, a knob to adjust the laser power (drive current), and a knob to adjust the temperature (TEC current). The back panel includes an input that allows the laser diode drive current to be controlled via an external voltage source and a remote interlock input. All of our fiber pigtailed lasers utilize 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. For applications that require several laser sources, consider the temperature stabilized four channel fiber coupled laser source.

S3FC Series FP Laser Specifications, Temperature Controlled

S3FC DFB Series Features

• Two Wavelengths Available: 1310 nm and 1550 nm
• Narrow Spectral Linewidths: <0.6 nm
• Thermo-Electric Temperature Stabilization
• 40 dB Optical Isolation
• Adjustable Temperature Set Point
• Adjustable Power
• Interlock Input

The S3FC Series Fiber Coupled Laser Sources feature a narrow linewidth DFB laser diode and a 40 dB optical isolator to eliminate back reflections and frequency jitter. The S3FC Series incorporates an integrated temperature control system for increased wavelength and power stability. The diode temperature and output power can be adjusted using the two front panel adjustment knobs, which ensures that the DFB laser diode can be tuned to match the laser cavity (see the Tuning tab). Also found on the front panel is a display that selectably shows either the output power in mW or the temperature in °C, a on / off key, an enable button, and the FC/PC bulkhead connector (wide 2.1 mm key compatible). The back panel includes an input that allows the laser diode drive current to be controlled via an external voltage source and a remote interlock input.

S3FC Series DFB Laser Specifications, Temperature Controlled

The benchtop laser source provides the ability to control not only the output power of the fiber coupled laser diode, it also allows for the precise control of the temperature at which the laser is operating. These two controls can be used to tune the fiber coupled laser diode to an optimum operating point, providing as stable an output as possible. The following graphs are from an OSA monitoring the output of a typical S3FC1550 laser.

The plots above show the effect of changing the operating current of the laser while maintaining a fixed operating temperature (in this case 24.5 °C). The first plot corresponds to a drive current of 75%. Notice the broad line width, the laser is not optimized but the output will appear to be stable. The next plot is at 80%. The laser is approaching a stable point but the second mode indicates the laser is not yet stable. The laser will randomly mode hop, shifting the power from one peak to another resulting in erratic performance and power output. In the third plot, the current is at 85% and shows a typical optimized DFB output: a single, very narrow line width and very stable power. The last two plots, taken at 90% and 95%, show the laser passing through the optimum point and starting to ebb again.

The plots below show the relationship of temperature verse stability. With the drive current fixed at 85% of maximum, the operating temperature was increased by 0.1°C per plot, starting at 24.3 °C. In the first plot, the laser appears stable but it can be improved. As the temperature is increased to 24.4 °C the laser enters a transition point between modes. At this temperature, the laser may mode hop resulting in erratic output. At 24.5 °C the laser has reached a stable operating point, indicated by the single narrow line width. The last two plots (24.7 °C and 24.9 °C) show the laser passing through the optimum point and decreasing in stability and desired output.

The examples above demonstrate the need to adjust the drive current and / or temperature of the laser diode in order to tune the output of the laser diode so that the output wavelength of the DFB laser diode matches laser cavity. There are multiple settings that will lase stably, and by varying one or both the lasing wavelength of the laser can be tuned over a narrow wavelength range.