Features

Setting the Standard in Laser Diode Protection

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 laser diodes.For more information about these protection features, please see our “Protecting Your Laser Diode" application note.

Unique Laser Diode Protection Feature

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.

High Stability Laser Control

The LDC-37X6 series offers optimal single-emitter low-noise performance. Since current noise scales with maximum current output, the LDC-37X6 series includes multiple current ranges. This flexibility allows users to select the range close to their maximum output to reduce current noise and provide future expansion when working with different laser diodes. This feature allows the LDC-37X6 series to deliver current stability better than 20 ppm for sensitive applications. Careful attention to the design of the thermoelectric temperature controller allows high power operation with low TEC current RMS noise. This reduces the chance of TEC noise coupling into the laser diode, which could potentially cause unstable operation.

Ease of Operation

The front panel of the LDC-37X6 Laser Controller was designed for ease of use and readability. The front panel features two large 7-segment displays that also have an integrated dot matrix display. Instrument controls are grouped by mode and function to allow for easy setup. The displays allow for easy viewing of multiple parameters including laser current output, laser voltage, photodiode measurement, measured temperature, set temperature, TEC current, and TEC voltage. Each display can be easily configured to display the most relevant measurements in your application. Laser control is directly addressable from the front panel "adjust" section. Instrument modes are easily selected or adjusted through discrete push buttons and a rotary digital encoder. Configuration of parameters is quickly accomplished through the "parameter" section.

A Choice of Laser Current Control Modes

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.

Built-in LIV Capability

The LDC-37X6 series instrument was designed with LIV as a feature. The instrument's firmware commands allows the user to make highly accurate LIV measurements with a single instrument by using the measurements of the photodiode, current, and voltage from the laser diode connection. This can be done using a laser diode's internal photodiode, or by using an external sensor for the light intensity feedback. This gives the user a quick, single-package solution for controlling and characterizing a laser diode.

Remote Operation

Remote instrument operation in an R&D or production environment is available through a USB or GPIB interface. Customizable LabVIEW® drivers are available for download. A trigger output is provided for integration into an automated measurement system where the TTL level output indicates a current step change is complete and the system is ready for initiation of a measurement.

Save and Recall Settings

For multiple instrument test configurations, LDC-37X6 Laser Controllers offer a STORE and RECALL feature. The STORE function allows the user to store all the front panel settings for any given instrument condition. The RECALL function allows the user 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.

Modulating with the LDC-37X6 Series

Each of the LDC-37X6 series provides a BNC input port for superimposing a modulated signal in addition to the DC current settings across the laser diode.  The use of a function generator is employed to perform standard analog modulated signals, as well as sending digital square wave pulse trains at lower modulation data rates.  The same laser protection safety features still apply, as any modulated amplitude will be current clamped to the maximum limit setting on the instrument.

Resources

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