Each laser diode driver’s laser current source can be operated in one of three modes:

• Constant current, low bandwidth: optimized for DC operation and offers improved laser protection and lowest noise
• Constant current, high bandwidth: the output stage supports up to 1MHz modulation frequency for dithering the laser current in power and wavelength tuning applications.
• Constant optical power: provides constant optical power operation of your laser diode by measuring the photocurrent from the laser diode’s rear-facet photodiode or an external photodiode in a feedback control loop to the current source.

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 clamping current limits, even under modulated conditions. In addition, exclusive braid-shielded cables have been specifically designed to suppress radiated noise and transients commonly found in laboratory or production environments. During power up, the laser is protected from over current and turn-on transient conditions by a slow start routine designed to ramp the current to the desired set point referred to as slow-start. 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.

A feature not found in competitors' controllers - fast output shutoff - provides an additional level of protection from intermittent contact between the laser and the current source. Intermittent contact can occur by loose or worn cables causing a momentary open in the circuit or by pogo-pins momentarily losing connection to the laser. If intermittent contact is left undetected, a severe voltage transient can occur which will damage sensitive lasers.

The front panel of the LDX-3200 Series Laser Diode Driver offers quick, easy operation and information display without confusing multi-layer menus. A bright, 5-digit, green LED display is easy to read from a distance, even with laser safety eyewear. Laser control is directly addressable from the front panel "adjust" section including a "fine adjustment" function for more precise control for sensitive operating parameters. Instrument parameters and modes are easily selected or adjusted through discrete pushbuttons and a rotary digital encoder. For automated testing or control applications, remote programming and control of the driver is easily accomplished through the GPIB/IEEE-488 interface. All driver functions are accessible through the interface bus, with commands based on a set of easy to- use mnemonics. Higher resolution measurements of current and voltage are also available through the GPIB interface. The LDX-3200 Series architecture simplifies routine maintenance. Closed-case calibration can be performed from the front panel or the GPIB interface. The instrument is placed in calibration mode through a unique combination of front panel push button presses or GPIB commands.

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 lower noise and stable output is required to ensure precise wavelength and power control. Each LDX-3200 Current Source offers digital 16-bit control and measurement allowing setpoint accuracies of +0.05%. Careful attention to design delivers source stability as low as 10ppm with low noise for precise control of laser diodes.