Multifunction optical transmitter for DWDM system

• US 6,563,846 B1
• Filed: 09/06/2000
• Issued: 05/13/2003
• Est. Priority Date: 09/07/1999
• Status: Expired due to Term

• Current Assignee: Optic153 LLC (Equitable IP Corporation)
• Original Assignee: Corvita Corporation (Boston Scientific Corporation)
• Inventors: Kuo, Chien-Yu, Gupta, Niraj
• Primary Examiner(s): PALADINI, ALBERT WILLIAM
• Application Number:
  US09/656,580
• Time in Patent Office: 979 Days
• Field of Search: 372/29.02, 372/29.021, 372/32, 372/34, 372/29.011, 372/38.01, 359/187
• US Class Current: 372/29.02
• CPC Class Codes: H04B 10/1149 Arrangements for indoor wireless networking of information
• CPC Class Codes: H04B 10/504 using direct modulation
• CPC Class Codes: H04B 10/564 Power control
• CPC Class Codes: H04B 10/572 Wavelength control
• CPC Class Codes: H04J 14/0221 Power control, e.g. to keep the total optical power constant
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0018 using tunable transmitters or receivers
• CPC Class Codes: H04Q 2011/0024 using space switching

Abstract

For optical transmitters in DWDM network systems, a method of operating the semiconductor laser which provides the output of the optical transmitter. The output power and wavelength of the semiconductor laser is set by controlling the bias current and operating temperature according to a closed theoretical mathematical form. The form has the variables of output power, wavelength, bias current and temperature related to each other by empirically determined coefficients. In this manner the optical transmitter can efficiently vary its output power while maintaining its wavelength constant, or vary its wavelength while maintaining its output power constant.

Claims

1. In a laser transmitter system for a DWDM network, said laser transmitter system having a semiconductor laser generating an output for said laser transmitter system and a control unit for controlling operations of said semiconductor laser, a method of operating said laser transmitter system comprising

storing in said control unit a closed mathematical form relating variables of output power, wavelength, bias current and operating temperature of said semiconductor laser, said variables related to each other by empirically determined coefficients;

storing in said control unit said empirically determined coefficients; and

setting said temperature to achieve the desired output power and wavelength of said semiconductor laser according the said closed mathematical form and empirically determined coefficients; and

setting said bias current based upon the temperature setting to achieve the desired wavelength of said semiconductor laser according the said closed mathematical form and empirically determined coefficients.

2. The method of claim 1 wherein said closed mathematical form comprises

3. The method of claim 2 wherein said closed mathematical form solution further comprises

4. The method of claim 1 wherein said semiconductor laser comprises a DFB laser.

5. The method of claim 1 wherein said semiconductor laser comprises a DBR laser.

6. The method of claim 1 wherein said setting of said temperature and bias current comprises keeping said wavelength constant as said output power is varied.

7. The method of claim 1 wherein said setting of said temperature and bias current comprises keeping said output power constant as said wavelength is varied.

8. The method of claim 1 wherein said setting of said temperature and bias current comprises varying said output power and said wavelength.

9. The method of claim 1 further comprises

storing in said control unit a plurality of set points of output power, wavelength, bias current and operating temperature according to said closed mathematical form and empirically determined coefficients for said semiconductor laser;

and

wherein said setting of said temperature and bias current comprises jumping to one of said points responsive to said control unit.

10. In a laser transmitter system for a DWDM network, said laser transmitter system having a semiconductor laser generating an output signal for said laser transmitter system, said output signal having power and a wavelength, a method of operating said laser transmitter system comprising

setting an operating temperature of said semiconductor laser to achieve the desired power and wavelength of said semiconductor laser according the a closed mathematical form relating variables of output power, wavelength, bias current and operating temperature of said semiconductor laser, said variables related to each other by empirically determined coefficients;

and

setting said bias current based upon the temperature setting to achieve the desired wavelength of said semiconductor laser according the said closed mathematical form and empirically determined coefficients.

11. The method of claim 10 wherein said closed mathematical form comprises

12. The method of claim 11 wherein said closed mathematical form solution further comprises

13. The method of claim 10 wherein said setting of said temperature and bias current comprises keeping said wavelength constant as said output power is varied.

14. The method of claim 10 wherein said setting of said temperature and bias current comprises keeping said output power constant as said wavelength is varied.

15. The method of claim 10 wherein said setting of said temperature and bias current comprises varying said output power and said wavelength.

16. The method of claim 10 further comprises

predetermining a plurality of set points of output power, wavelength, bias current and operating temperature according to said closed mathematical form and empirically determined coefficients for said semiconductor laser;

and

wherein said setting of said temperature and bias current comprises jumping to one of said predetermined set points.