Segmented vertical cavity surface emitting laser
A VCSEL device includes a first electrical contact, a substrate, a second electrical contact, and an optical resonator arranged on a first side of the substrate. The optical resonator includes a first reflecting structure comprising a first distributed Bragg reflector, a second reflecting structure comprising a second distributed Bragg reflector, an active layer arranged between the first and second reflecting structures, and a guiding structure. The guiding structure is configured to define a first relative intensity maximum of an intensity distribution within the active layer at a first lateral position such that a first light emitting area is provided, to define at least a second relative intensity maximum of the intensity distribution within the active layer at a second lateral position such that a second light emitting area is provided, and to reduce an intensity in between the at least two light-emitting areas during operation.
1. A Vertical Cavity Surface Emitting Laser (VCSEL) device, comprising:
a first electrical contact;
a substrate;
a second electrical contact;
an optical resonator arranged on a first side of the substrate; the optical resonator comprising:
a first reflecting structure comprising a first distributed Bragg reflector,
a second reflecting structure comprising a second distributed Bragg reflector,
an active layer arranged between the first reflecting structure and the second reflecting structure, and
a guiding structure configured (i) to define a first relative intensity maximum of an intensity distribution within the active layer at a first lateral position of the optical resonator such that a first light emitting area is provided, (ii) to define at least a second relative intensity maximum of the intensity distribution within the active layer at a second lateral position of the optical resonator such that a second light emitting area is provided, and (iii) to reduce an intensity of the intensity distribution in between the at least two light-emitting areas during operation of the VCSEL device,
wherein the guiding structure is arranged within a layer stack of the first distributed Bragg reflector or the second distributed Bragg reflector and arranged within and fully enclosed by the optical resonator,
wherein a first optical mode contributes to the first relative intensity maximum and a second optical mode, which is different from the first optical mode, contributes to the second relative intensity maximum, and
wherein the guiding structure comprises a variation of a thickness of at least one layer of the first distributed Bragg reflector or the second distributed Bragg reflector.
2. The VCSEL device according to claim 1 , wherein the guiding structure is arranged inside a layer stack of the first distributed Bragg reflector or the second distributed Bragg reflector in a vertical direction of the VCSEL device.
3. The VCSEL device according to claim 1 , wherein the guiding structure is configured to reduce an intensity of at least one optical mode contributing to at least one of the first or second relative intensity maximum outside the at least the first or the second light emitting area such that a lateral extension of the light emitting areas is bound to the respective lateral position of the optical resonator.
4. The VCSEL device according to claim 1 , wherein the guiding structure is configured to provide a lateral variation of a reflectivity of the first reflecting structure or the second reflecting structure parallel to the active layer.
5. The VCSEL device according to claim 1 , wherein the guiding structure comprises a lateral variation of a reflectivity of the first electrical contact or the second electrical contact.
6. The VCSEL device according to claim 1 , wherein the guiding structure comprises oxidized regions within at least one layer of the first distributed Bragg reflector or the second distributed Bragg reflector, wherein the oxidized regions are arranged to reduce the intensity in between the light-emitting areas.
7. The VCSEL device according to claim 1 , wherein the optical resonator further comprises a distributed heterojunction bipolar phototransistor comprising:
a collector layer,
a light sensitive layer,
a base layer, and
an emitter layer,
wherein the distributed heterojunction bipolar phototransistor is arranged such that there is an optical coupling between the active layer and the distributed heterojunction bipolar phototransistor for providing an active carrier confinement the distributed heterojunction bipolar phototransistor.
8. The VCSEL device according to claim 7 , wherein the guiding structure is arranged outside a current flow configured to be provided by the first electrical contact and the second electrical contact during operation of the VCSEL device.
9. The VCSEL device according to claim 1 , wherein the guiding structure is further configured to provide across the lateral cross section of the optical resonator regions with an effective optical length enabling resonant laser operation intermitted by regions with a different effective optical length inhibiting laser operation.
10. The VCSEL device according to claim 1 , wherein the guiding structure is further configured to provide a local current confinement at the light-emitting areas.
11. The VCSEL device according to claim 1 , wherein the optical resonator comprises an extended optical cavity across the substrate, and wherein the guiding structure comprises a lateral structuring of a second side of the substrate opposing the first side of the substrate.
12. An optical sensor comprising the VCSEL device according to claim 1 .
13. A mobile communication device comprising at least one optical sensor according to claim 12 .
14. A method of fabricating a Vertical Cavity Surface Emitting Laser (VCSEL), the method comprising the steps of:
providing a first electrical contact;
providing a substrate;
providing a first distributed Bragg reflector;
providing an active layer;
providing a second distributed Bragg reflector;
providing a second electrical contact; and
providing a guiding structure configured (i) to define a first relative intensity maximum of an intensity distribution within the active layer at a first lateral position of the optical resonator such that a first light emitting area is provided, (ii) to define at least a second relative intensity maximum of the intensity distribution within the active layer at a second lateral position of the optical resonator such that a second light emitting area is provided, (iii) to reduce an intensity of the intensity distribution in between the at least two light-emitting areas during operation of the VCSEL device,
wherein the guiding structure is arranged within a layer stack of the first distributed Bragg reflector or the second distributed Bragg reflector and arranged within and fully enclosed by the optical resonator,
wherein a first optical mode is contributing to the first relative intensity maximum and a second optical mode, which is different from the first optical mode, is contributing to the second relative intensity maximum, and
wherein the guiding structure comprises:
a variation of a thickness of at least one layer of the first distributed Bragg reflector or the second distributed Bragg reflector, or
a lateral variation of a reflectivity of the first electrical contact or the second electrical contact.
15. The method according to claim 14 , wherein the guiding structure comprises the lateral variation of the reflectivity of the first electrical contact or the second electrical contact.
16. The method according to claim 14 , wherein the guiding structure comprises the variation of the thickness of at least one layer of the first distributed Bragg reflector or the second distributed Bragg reflector.
17. A Vertical Cavity Surface Emitting Laser (VCSEL) device, comprising:
a first electrical contact;
a substrate;
a second electrical contact;
an optical resonator arranged on a first side of the substrate; the optical resonator comprising:
a first reflecting structure comprising a first distributed Bragg reflector,
a second reflecting structure comprising a second distributed Bragg reflector,
an active layer arranged between the first reflecting structure and the second reflecting structure, and
a guiding structure configured (i) to define a first relative intensity maximum of an intensity distribution within the active layer at a first lateral position of the optical resonator such that a first light emitting area is provided, (ii) to define at least a second relative intensity maximum of the intensity distribution within the active layer at a second lateral position of the optical resonator such that a second light emitting area is provided, and (iii) to reduce an intensity of the intensity distribution in between the at least two light-emitting areas during operation of the VCSEL device,
wherein the guiding structure is arranged within a layer stack of the first distributed Bragg reflector or the second distributed Bragg reflector and arranged within and fully enclosed by the optical resonator,
wherein a first optical mode contributes to the first relative intensity maximum and a second optical mode, which is different from the first optical mode, contributes to the second relative intensity maximum, and
wherein the guiding structure comprises a lateral variation of a reflectivity of the first electrical contact or the second electrical contact.