Laser diodes act as a gain medium. Small drive current fluctuations due to noise and drift are amplified optically. Because of this, a controller with a low noise and stable output is required to ensure stable optical output. The LDC-3700C Series of controllers make this possible. Each LDC-3700C Controller offers a precision 16-bit current source with 0.05% accuracy. Careful attention to design delivers as low as 20 ppm stability and 1.5 µA of noise so component measurements can be made with confidence.

Laser diodes are extremely sensitive to electro-static discharge, excessive current levels, current spikes, or transients from power surges or other laboratory equipment. One of the most important features we have implemented into each instrument is the ILX Lightwave proven laser diode protection standards. These standards have led to advanced protection features such as adjustable compliance voltage limit, and fast output shut-off to limit device damage from intermittent contact. In addition, the current limit setting is independent of the voltage drop of the device connected to the laser output. Because the current limit circuitry is fully independent of the main current control, the current limit can be adjusted safely, even while the laser output is active. These protection features work in conjunction with all instrument modes of operation, providing worry free, fail safe control of your laser diode. For more information about these protection features, please see our “Protecting Your Laser Diode" application note.

The LDC-3700C Series Controllers include an integrated precision 32W temperature controller for quick temperature response of the laser diode’s chip temperature. For precise wavelength control during component testing, the LDC-3700C Series control algorithm maintains temperature with a stability of 0.004°C. Sixteen-bit control and measurement allows you to set temperature with 0.01°C resolution with a measurement accuracy of 0.05°C (with a calibrated sensor). In addition, the LDC-3700C series supports TEC forward voltage measurement for monitoring the total power consumption of your laser diode module.

These controllers offer extended temperature control from -100°C to 199.9°C with a choice of thermistor, IC, or RTD temperature sensors. Temperature can be controlled in one of three modes: constant temperature, constant sensor, or constant TE current. As an added precaution, if the temperature sensor or TE module circuit should open during operation, the laser diode current source output will be shut off and the appropriate fault indicator LED will illuminate. In addition to the normal control modes, the TEC output of the LDC-3700C Controllers is bounded by a fully independent hardware current limit to protect the laser diode’s internal TE module. These limits cannot be exceeded in any mode of operation. The controller can also be bounded by a high temperature limit setting.

Divided into two sections, TEC and LASER, the front panel offers quick, easy operation and information display without confusing multi-layer menus. Each bright, 5-digit, green LED display is easy to read from a distance, even with laser safety goggles. Each channel is directly addressable from the front panel "adjust" section with LASER and TEC parameters and modes easily selected or adjusted through discrete pushbuttons and a rotary digital encoder

For multiple instrument test configurations, the LDC-3700C Controllers offer a SAVE and RECALL feature. The SAVE function allows you to store all the front panel settings for any given instrument condition. The RECALL function allows you to retrieve any of the saved conditions at any time. This saves time in instrument re-configuration for different production runs or R&D experiments.