Vertical cavity surface emitting laser and sensor

• US 5,331,658 A
• Filed: 08/26/1992
• Issued: 07/19/1994
• Est. Priority Date: 08/26/1992
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Shieh, Chan-Long, Ackley, Donald E.
• Primary Examiner(s): Davie, James W.
• Application Number:
  US07/935,307
• Time in Patent Office: 692 Days
• Field of Search: 372/50, 372/99, 372/92, 372/20, 372/38
• US Class Current: 372/50.124
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: H01S 5/0028 Laser diodes used as detectors
• CPC Class Codes: H01S 5/0264 for monitoring the laser-output
• CPC Class Codes: H01S 5/0607 by varying physical parameters other than the potential of the electrodes, e.g. by an electric or magnetic field, mechanical deformation, pressure, light, temperature
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18363 comprising air layers
• CPC Class Codes: H01S 5/18366 Membrane DBR, i.e. a movable DBR on top of the VCSEL
• CPC Class Codes: H01S 5/18375 based on metal reflectors
• CPC Class Codes: H01S 5/18377 comprising layers of different kind of materials, e.g. combinations of semiconducting with dielectric or metallic layers
• CPC Class Codes: H01S 5/2063 obtained by particle bombardment

Abstract

A vertical cavity surface emitting laser (VCSEL) having sensing capabilities is fabricated by forming a layer having the capability to change the threshold current of the VCSEL. This can be accomplished by forming a deformable membrane or a cantilevered beam on the VCSEL. The deformation of movement of the beam causes a change in the threshold current of the VCSEL, so that it can go from lasing to nonlasing or vice versa. In addition, a layer which changes reflectivity in the presence of a particular chemical can also be formed on the VCSEL to produce the same result.

Claims

1. A semiconductor laser operating at a particular wavelength and having a threshold current, comprising:

a semiconductor supporting structure;

a first mirror stack positioned above said supporting structure;

an active layer comprised of at least one light emitting region positioned above said first mirror stack;

a second mirror stack positioned above said active layer; and

a means for changing said threshold current of said semiconductor laser upon sensing a change in an environment positioned above said second mirror stack.

2. The semiconductor laser of claim 1 wherein said means for changing said threshold current is comprised of a deformable, reflective layer positioned above said second mirror stack, wherein said deformable, reflective layer is positioned in a range of approximately 1/4 or 1/2 said wavelength of operation above said second mirror stack.

3. The semiconductor laser of claim 2 wherein said means for changing said threshold current is comprised of a reflectivity changeable layer having a thickness of approximately 1/4 said wavelength of operation.

4. The semiconductor laser of claim 2 wherein said means for changing said threshold current is comprised of a silicon/silicon dioxide mirror stack.

5. The semiconductor laser of claim 1 wherein said means for changing said threshold current forms an air bridge having an air gap in a range of approximately 1/4 or 1/2 wave between said second mirror stack and said first layer.

6. The semiconductor laser of claim 1 wherein said means for changing said threshold current is comprised of a displaceable beam positioned in a range of approximately 1/4 or 1/2 wave above said second mirror stack.

7. The semiconductor laser of claim 1 wherein said means for changing said threshold current is comprised of an anti-reflective, 1/4 wave thick layer formed on said second mirror stack which has a capability to change reflectivity in a presence of a chemical.

8. The semiconductor laser of claim 1 further comprising a photodiode positioned within said semiconductor laser.

9. The semiconductor laser of claim 1 further comprising a phototransistor positioned within said semiconductor laser.

10. A semiconductor laser, operating at a particular wavelength and having a threshold current, comprising:

a semiconductor supporting structure;

a first mirror stack positioned above said supporting structure;

an active layer comprised of at least one light emitting region positioned above said first mirror stack;

a second mirror stack positioned above said active layer; and

a first layer positioned above said second mirror stack which is capable of changing said threshold current of said semiconductor laser upon a change in an environment.

11. The semiconductor laser of claim 10 wherein said first layer is comprised of a deformable, reflective layer positioned above said second mirror stack, wherein said deformable, reflective layer is positioned in a range of approximately 1/4 or 1/2 said wavelength of operation above said second mirror stack.

12. The semiconductor laser of claim 10 wherein said first layer is comprised of a reflectivity changeable layer having a thickness of approximately 1/4 said wavelength of operation.

13. The semiconductor laser of claim 11 wherein said first layer is comprised of a silicon/silicon dioxide mirror stack.

14. The semiconductor laser of claim 10 wherein said first layer forms an air bridge having an air gap in a range of approximately 1/4 or 1/2 wave between said second mirror stack and said first layer.

15. The semiconductor laser of claim 10 wherein said first layer is comprised of a displaceable beam positioned in a range of approximately 1/4 or 1/2 wave above said second mirror stack.

16. The semiconductor laser of claim 10 wherein said first layer is comprised of an anti-reflective, 1/4 wave thick layer formed on said second mirror stack which has a capability to change reflectivity in a presence of a chemical.

17. The semiconductor laser of claim 10 further comprising a photodiode positioned within said semiconductor laser.

18. The semiconductor laser of claim 10 further comprising a phototransistor positioned within said semiconductor laser.

19. A method of fabricating a semiconductor laser, operating at a particular wavelength and having a threshold current, comprising the steps of:

providing a semiconductor supporting structure;

forming a first mirror stack positioned above said supporting structure;

forming an active layer comprised of at least one light emitting region positioned above said first mirror stack;

forming a second mirror stack positioned above said active layer; and

forming a means for changing said threshold current of said semiconductor laser upon sensing a change in an environment positioned above said second mirror stack.

20. The method of claim 19 wherein means for changing said threshold current comprises forming a deformable, reflective layer positioned above said second mirror stack, wherein said deformable, reflective layer is positioned in a range of approximately 1/4 or 1/2 said wavelength of operation above said second mirror stack.

21. The method of claim 19 wherein forming said means for changing said threshold current comprises forming a reflective metal.

22. The method of claim 19 wherein forming said means for changing said threshold current comprises forming a silicon/silicon dioxide mirror stack.

23. The method of claim 19 wherein forming said means for changing said threshold current comprises forming an air bridge having an air gap in a range of approximately 1/4 or 1/2 wave between said second mirror stack and said first layer.

24. The method of claim 19 wherein forming said means for changing said threshold current comprises forming a displaceable beam positioned in a range of approximately 1/4 or 1/2 wave above said second mirror stack.

25. The method of claim 19 wherein forming said means for changing said threshold current comprises forming an anti-reflective, 1/4 wave thick layer formed on said second mirror stack which has a capability to change reflectivity in a presence of a chemical.

26. The method of claim 19 further comprising forming a photodiode positioned within said semiconductor laser.

27. The method of claim 19 further comprising forming a phototransistor positioned within said semiconductor laser.