Optoelectronic device and method of operating optoelectronic device
View Patent ↗The invention provides an optoelectronic device combining a vertical cavity surface emitting laser (VCSEL) and a photodetector for monitoring the output power of the vertical cavity surface emitting laser. To improve the signal-to-noise ratio of the photodetector, a light deflector is interposed between the photodetector and the VCSEL.
1. An optoelectronic device comprising:
a substrate, a vertical cavity surface emitting laser (VCSEL) formed on the substrate, the VCSEL comprising an active layer sandwiched between an output side Bragg mirror and a non-output side Bragg mirror and such that the intensity of light emitted through the output side Bragg mirror is greater than that emitted through the non-output side Bragg mirror,
a light receptive device to receive and detect light emitted through the non-output side mirror of the VCSEL, and
a light deflector is interposed between the light receptive device and the non-output side mirror of the VCSEL, the light deflector being effective to deflect light emitted through non-output side Bragg mirror to reduce the amount of light received by the light receptive device having a propagation direction with an inclination to an axis of the laser cavity of the VCSEL,
wherein the light deflector comprises at least one of a curved surface structure formed between the non-output side Bragg mirror and the light receptive device, the curved surface structure defining a transition in the index of refraction, an optically concave multifaceted structure, and an angle selective coating layer wherein light propagating in a narrow angle region around a cavity axis of the VCSEL passes through the light deflector, and off-axis light is deflected at the light deflector.
2. An optoelectronic device according to claim 1 , wherein the light deflector is an optically concave shaped structure.
3. An optoelectronic device according to claim 1 , wherein the light deflector is an optically planoconvex shaped lens-type structure.
4. An optoelectronic device according to claim 1 , wherein the deflector is formed by a material recess in a device layer interposed between the non-output side mirror of the VCSEL and the light receptive device.
5. An optoelectronic device according to claim 1 , wherein the light receptive device is a photodiode.
6. An optoelectronic device according to claim 1 comprising a plurality of angle selective coating layer structures.
7. An optoelectronic device according to claim 1 , wherein the light receptive device is bonded to the VCSEL forming a hybrid integrated structure.
8. An optoelectronic device according to claim 7 , wherein the bonding comprises solder bonds or electrically conductive adhesive.
9. An optoelectronic device according to claims 7 , wherein the bonding comprises optically transparent adhesive.
10. An optoelectronic device according to claim 1 , wherein the light receptive device is a component in an integrated electrical circuit.
11. An optoelectronic device according to claim 1 , wherein the relative orientation of the VCSEL and the light receptive device is such that the non-output-side Bragg mirror is disposed between the output side Bragg mirror and the substrate, and the substrate is disposed between the non-output side Bragg mirror and the light receptive device.
12. An optoelectronic device according to claim 11 , wherein the light receptive device is bonded to the substrate on which the VCSEL is formed.
13. An optoelectronic device according to claim 1 , wherein the relative orientation of the VCSEL and light receptive device is such that the output side Bragg mirror is disposed between the non-output side Bragg mirror and the substrate, and the non-output side Bragg mirror is disposed between the output side Bragg mirror and the light receptive device.
14. An optoelectronic device according to claim 13 , wherein a top surface of the VCSEL is bonded to the light receptive element by flip-chip bonding.
15. An optoelectronic device according to claim 1 , wherein the light deflector is formed by an interface between adjacent materials with a refractive index ratio at the emitting wavelength of at least 1.5, preferably at least 2 and more preferably at least 3.
16. An optoelectronic device according to claim 1 , wherein the VCSEL has a beam size with a first lateral extension, and the light deflector has a second lateral extension, wherein the second lateral extension is between 2 and 4 times greater than the first lateral extension.
17. An optoelectronic device according to claim 16 , wherein the beam size has a cross sectional diameter in a range of 2 to 20 μm.
18. An optoelectronic device according to claim 1 , wherein a width of a light receiving area of the light receptive device is larger than a width of the beam emitted by the VCSEL, preferably larger than 10 times the width of the beam.
19. An optical positioning device comprising an optoelectronic device according to claim 1 .
20. An optical positioning device according to claim 19 , wherein the positioning device is a computer mouse.
21. An optoelectronic device according to claim 1 , wherein the light deflector comprises an optically concave multifaceted structure, the optically concave multifaceted structure comprising:
a central plane surface that is substantially perpendicular to the cavity axis of the VCSEL; and
a plurality of sloping surfaces adjacent the central plane surface that are substantially plane surfaces with a slope with respect to the central plane surface.