Features

• Superluminescent Diodes (SLDs) with Broadband Emissions Centered at 1310 or 1550 nm
• Single Mode (SM) or Polarization-Maintaining (PM) Fiber Output Channel
• FC/APC Bulkhead Connector
• TEC Temperature Stabilized
• Low Noise Output (<0.1%)
• USB 2.0 Interface Allows Full Operation Through a PC Interface
• Every S5FC Ships with a Complete Test Report

Thorlabs' Fiber-Coupled SLD Sources provide easy coupling and simple control of Superluminescent Diodes (SLDs). Each system is equipped with a single fiber output, is available with output centered at either 1310 nm or 1550 nm, and can be purchased with either SM or PM fiber.

Superluminescent Diodes are excellent high-power broadband light sources for use as ASE Light Sources and in applications like Optical Coherence Tomography (OCT) Imaging Systems and Fiber Optic Gyroscopes (FOG). The SLDs offered here are indium phosphide (InP) devices manufactured by Thorlabs.

The SLD operates from an independent, high-precision, low-noise, constant-current source and temperature control unit. An intuitive LCD interface allows the user to view the parameters for the SLD. For more details, please see the Operation tab.

This device includes a microcontroller to fully regulate the SLDs optical power and temperature as well as to monitor the system for fault conditions. The S5FC source includes a USB connection that allows remote adjustment of power, temperature, and enabling. On the rear panel, an analog input is available to modulate the SLD with an external signal of 0 to 5 V, which is added to the internal set point. To prevent damage, the microcontroller will disable the output if the analog input plus the internal set point exceeds the SLD limits.

The S5FC includes a universal power supply allowing operation over 100 to 240 VAC without the need for selecting the line voltage. The fuse access is conveniently located on the rear panel.

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Viewing Information

Thorlabs' SLDs use a single four quadrant LCD to display information as shown in the photograph to the right (Digital Display with Backlight).

• Top left: Indicates device type
• Top Right: Indicates the wavelength of the SLD internal to the S5FC
• Bottom Left: If a monitor diode is included in the SLD package, a power reading (in mW) will be displayed. When enabled, the current power level determined from the monitor photodiode will indicate the approximate power level of the output. When disabled, the power level will read "0.00 mW". If a monitor diode is not included in the SLD package, a current reading (in mA) will be indicated instead
• Bottom Right: Indicates the actual temperature (in °C) the SLD is stabilized to. The default temperature is set to 25.00 °C and is user adjustible

Adjusting the SLD Output Power and Temperature

The control knob/switch utilizes an intelligent speed control. Turning the knob slowly corresponds to fine adjustment while turning the knob quickly corresponds to coarse adjustment. The SLD current threshold is a user-selectable command parameter that allows the user to filter out nonlinear sections of the SLD power curve. The threshold current is defaulted to 1 mA on initial power up.

The unit will be in display mode when it is first turned on to show the variables such as power reading, temperature, and wavelength. Press the control knob/switch once enables the current control mode. Simply turn the knob will allow the user to adjust the current. Press the control knob one more time enables temperature control mode. The user will be able to adjust temperature in this mode. The resolution for the current adjustment is 0.1 mA and 0.01 °C for temperature adjustment.

Modulating the SLD Output

The Analog In input can be used to modulate the SLD output or to set the SLD output remotely using a 5 V power source. The 5 V maximum input corresponds to the maximum calibrated power, which operates using a constant current drive technique. The resulting actual output power is dependent on the set current and operating temperature. In addition, in order to eliminate a dead zone in the power control knob, the output of the unit is offset to the threshold current of the coupled SLD diode. Adjusting the knob below threshold will immediately set the current to 0.0 mA, or Standby mode. Therefore, there are two modes of modulation available. First setting the control to "Standby" allows the analog modulation to utilize the full 0 to 5 V input range. The drawback is that a minimum voltage will be required to operate above the threshold current but allows more flexibility by the user. The second mode is to adjust the control knob so that the SLD is at threshold or above. The analog modulation voltage will be limited to less than 5 V, but a DC offset will not be required. This should be kept in mind when using the modulation input since it will limit the actual input voltage range.

Making the Safety Interlock Connections

Pins must be shorted in order for device to be in the "ON" state.

The S5FC series of SLD sources are equipped with a remote interlock connector located on the rear panel. All units have this feature regardless of their FDA and IEC classifications. In order to enable the S5FC source, a short circuit must be applied across the terminals of the Remote Interlock connector. In practice this connection is made available to allow the user to connect a remote-actuated switch to the connector (i.e., an open door indicator). The switch (which must be normally open) has to be closed in order for the unit to be enabled. Once the switch is in an open state, the S5FC source will automatically shut down. If the switch returns to a closed condition, the S5FC source must be re-enabled at the unit by pressing the ENABLE switch.