Laser driver with temperature sensor on an integrated circuit

• US 5,844,928 A
• Filed: 02/20/1997
• Issued: 12/01/1998
• Est. Priority Date: 02/27/1996
• Status: Expired due to Term

• Current Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Snyder, David Alan, Shastri, Kalpendu Ranjitrai
• Primary Examiner(s): Lee, John D.
• Application Number:
  US08/803,405
• Time in Patent Office: 649 Days
• Field of Search: 372/9, 372/29, 372/31-34, 372/38
• US Class Current: 372/38.02
• CPC Class Codes: H01S 5/0617 using memorised or pre-programmed laser characteristics
• CPC Class Codes: H01S 5/06804 by monitoring an external parameter, e.g. temperature
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

There is disclosed a laser driver or transmitter in which a drive current is generated by monitoring the temperature of an integrated circuit that generates drive current for the laser. The temperature sensed at the integrated circuit is transformed to a corresponding temperature at the laser. A drive current is generated for the laser that is dependent on the corresponding temperature at the laser.

Claims

1. A method of generating a drive current for a laser, comprising the steps of:

monitoring the temperature of an integrated circuit that generates drive current for a laser, the integrated circuit remotely located with respect to said laser;

converting the temperature of the integrated circuit to a corresponding temperature at the laser; and

generating a drive current for the laser that is a function of the corresponding temperature at the laser.

2. The method as recited in claim 1, wherein the converting step comprises entering a look-up table with a representation of the integrated circuit temperature to obtain the corresponding temperature at the laser.

3. The method as recited in claim 1, wherein the generating step comprises:

predetermining a plurality of discrete drive currents over a range of corresponding laser temperatures; and

storing a digital representation of the plurality of discrete drive currents in a look-up table.

4. The method as recited in claim 3, further comprising the steps of:

entering the look-up table based on a temperature of the integrated circuit; and

retrieving from the look-up table a digital representation of one of the plurality of drive currents that correlates to the temperature of the integrated circuit.

5. A laser transmitter, comprising

a laser for receiving a drive current and for emitting light in response thereto;

an integrated circuit for generating the drive current for the laser and remotely located with respect to said laser, the integrated circuit comprising a temperature sensing circuit that senses the temperature of the integrated circuit, the integrated circuit converting the temperature at the integrated circuit to a representation corresponding to the temperature at the laser;

a look-up table for receiving the representation corresponding to the temperature at the laser and for generating a representation of a corresponding drive current; and

a driver for converting the representation of the drive current into a drive current, the drive current provided to the laser.

6. The laser transmitter as recited in claim 5, wherein the look-up table is stored in an electrically erasable programmable read only memory.

7. The laser transmitter as recited in claim 5, wherein the representation of the corresponding drive current is a digital representation.

8. The laser transmitter as recited in claim 7, wherein the driver is a digital-to-analog converter.