Summit Microelectronics Laser Control Device Directly Compensates for Temperature of Laser Diode
Source: Summit Microelectronics
Campbell, CA. Summit Microelectronics Inc. has introduced the industry s first laser control device which compensates for the operating temperature of the laser itself, the SML2108 adaptive power controller. This device will greatly simplify the design and implementation of high-speed fiber-optic transceivers by eliminating the need for costly thermal electric coolers.
"The design of high fiber-optic transceivers has been complicated by the lack of a means of adjusting the modulation current of the laser based upon the temperature of the laser itself to maintain a constant extinction ratio," stated Rick Orlando, president and chief executive officer of Summit. "This has led to the widespread use of thermal electric coolers to attempt to hold the laser at a constant temperature, an approach which increases the footprint, cost and power consumption of the transceiver."
Adaptive thermal control of the laser has two distinct problems. The first is the method used to measure the temperature of the laser itself, rather than the ambient temperature. Summit s unique approach directly measures the bias current of the laser to determine the temperature of the laser itself.
Once the temperature of the laser is determined, the second challenge is how to compensate control the modulation current, since each individual laser will have its own unique non-linear characteristic. The Summit SML2108 uses a 256 X 8 look-up table, which is programmed at the testing of the transceiver, to generate 256 individual compensation factors. The output of this table can is used to drive a modulation current source which can be configured to operate in 0-5 mA for Vicsel applications and 0-100 mA for long-haul applications.
The SML2108 also includes an automatic power control circuit to maintain constant average power through bias current control. A 10-bit nonvolatile DAC is used in the device to set the initial bias current values. The integration of both bias and modulation current control eliminates the need for these functions to be placed on the laser modulating circuit, allowing the design and use of more simplified laser drivers. All configuration of the device is accomplished through an industry standard I2C interface.
"The SML2018 represents a major change in the way fiber optics transceivers will be designed in the future," continued Orlando. "The domination of fiber optics in the networking and communications market can only be realized if the transceivers become smaller, cheaper and lower power. The first step in this evolution is to eliminate the need for the thermal electric cooler while maintaining optimized performance at a wide range of ambient temperatures. The SML2108 enables this evolution."
Pricing and Availability
The SML2108 laser diode adaptive power controller offers 3V or 5V operation and is available now in a 48-lead TQFP. Quantity pricing is $9.40 in 1000 piece quantities; $7.50 in 10,000 piece quantities.
About Summit
Summit Microelectronics develops semiconductors that manage the power functions in communications system equipment. Using Summit s proprietary technology, customers can achieve carrier-class availability, the highest standard of reliability available today for telecommunications, data communications and Internet applications. Founded in 1997, Summit is headquartered in Campbell, California. The Company is ISO 9001 certified and is in the process of gaining ISO 14000 and STACK certification. Summit s website is www.summitmicro.com.
Contact: Maestro Public Relations Barbara Kalkis Tel: 408/996-9975 kkalkis@compuserve.com
Maestro Public RelationsBarbara Kalkis
Tel: 408/996-9975
kkalkis@compuserve.com
E-mail: kkalkis@compuserve.com
Web site: http://www.summitmicro.com
