As its primary method of protection, Lasorb includes a slew-rate detector, which monitors the slew rate of the voltage across the pins of the laser diode. If there is a fast change-of-voltage condition detected, this triggers the device to aggressively conduct the voltage (and thus current) away from the laser diode. The conduction is initiated very rapidly—in some cases less than one nanosecond—and the conduction can last from several microseconds to tens of microseconds (the actual slew rate, surge conduction time, and maximum operating voltage can be specified).
This change-of-voltage approach is a good principle to use for laser diodes because, under ordinary circumstances, even during modulation the voltage across laser diode pins does not change very much. Therefore, any change of voltage, especially a fast one, indicates an abnormal event—something that happens only during ESD or other types of electrical faults. This method allows the device to protect a laser diode at all times, whether it is lasing or not.
During component development in 2007 and since, we have tested hundreds of laser diodes ranging from low-power infrared (IR) diodes, to Blu-ray disc lasers, to high-power laser diode bars. In our testing, Lasorb was found to be 100% effective at protecting these laser diodes from positive-ESD events up to 15 kV, when using the human body model associated with ANSI/ESD STM5.1 and IEC 61340-3-1. The component was also able to protect all laser diodes from negative-ESD up to 15 kV, when using the human body model associated with ANSI/ESD STM5.1 and IEC 61340-3-1 as well as IEC 61000-4-2.
For example, KVANT (Bratislava, Slovakia), which makes laser display systems and laser modules for scientific applications, integrated the component into its existing lineup of modules and systems. As a result, it reduced returns and failures in the field by 15%, leading to a substantial cost savings.
The component can serve in numerous configurations and can be customized, offering protection for IR, red, green, blue, Blu-ray, quantum cascade, and series connected lasers.
William R. Benner Jr. is president and chief technology officer at Pangolin Laser Systems, Orlando, FL;
e-mail: email@example.com; www.lasorb.com.