Coupled resonant cavity surface-emitting laser
View Patent ↗The CRCSEL comprises a single-mode optical gain structure and an optically-resonant cavity. The single-mode optical gain structure is structured to generate excitation light having a wavelength and a direction. The optically-resonant cavity is optically coupled to the single-mode optical gain structure and is structured to emit an output light beam in a direction substantially orthogonal to the excitation light. The change in light direction provided by the optically-resonant cavity enables the output light beam to emit from a surface while allowing the excitation light to be generated in a large, high-gain single-mode optical gain structure.
1. A surface-emitting laser, comprising a layer structure, the layer structure comprising:
a single-mode optical gain structure structured to generate excitation light having a wavelength and a direction, the optical gain structure surrounded by an evanescent field associated with the excitation light; and
an optically-resonant cavity located alongside the single-mode optical gain structure not intersecting therewith, the optically-resonant cavity optically coupled by the evanescent field to the single-mode optical gain structure to receive part of the excitation light therefrom, the optically-resonant cavity structured to emit an output light beam in a direction orthogonal to the direction of the excitation light.
2. The surface-emitting laser of claim 1 , in which the single-mode optical gain structure includes an elongate optical waveguide through which the excitation light propagates.
3. The surface-emitting laser of claim 2 , in which the waveguide includes and active region in which the excitation is generated.
4. The surface-emitting laser of claim 3 , in which the single-mode optical gain structure additionally includes reflective elements operative to impose a single mode on the excitation light.
5. The surface-emitting laser of claim 3 , in which the single-mode optical gain structure comprises one-dimensional distributed Bragg reflectors separated from one another along the length of the waveguide.
6. The surface-emitting laser of claim 3 , in which the single-mode optical gain structure comprises a diffraction grating disposed along the length of the waveguide.
7. The surface-emitting laser of claim 1 , in which the optically-resonant cavity includes:
a cavity-defining structure of a cavity-defining structure material having a first dielectric constant; and p 1 a material filling interstices in the cavity-defining structure, the material having a second dielectric constant different from the first dielectric constant.
8. The surface-emitting laser of claim 1 , in which the optically-resonant cavity is structured to emit the output light beam with an axially symmetric radiation pattern.
9. The surface-emitting laser of claim 1 , in which the layer structure additionally comprises:
a substrate of gallium arsenide; and
a layer of embedding material in which the optically-resonant cavity is located, the embedding material including aluminum arsenide.
10. The surface-emitting laser of claim 1 , in which the layer structure additionally comprises:
a substrate of indium phosphide; and
a layer of embedding material in which the optically-resonant cavity is located, the embedding material including indium gallium arsenide phosphide.
11. The surface-emitting laser of claim 1 , in which the layer structure additionally comprises at least one additional optically-resonant cavity optically coupled to the single-mode optical gain structure, each of the at least one optically-resonant cavity structured to emit a respective output light beam in a direction substantially orthogonal to the excitation light.
12. The surface-emitting laser of claim 1 , in which the optically-resonant cavity is located alongside the single-mode optical gain structure and separated therefrom by a distance of less than one wavelength of the excitation light.
13. A surface-emitting laser, comprising:
a single-mode optical gain structure structured to generate excitation light having a wavelength and a direction; and
an optically-resonant cavity optically coupled to the single-mode optical gain structure to receive part of the excitation light therefrom, the optically-resonant cavity structured to emit an output light beam in a direction orthogonal to the excitation light, the optically-resonant cavity comprising:
a cavity-defining structure of a cavity-defining structure material having a first dielectric constant, the cavity-defining structure comprising:
a reflective cylinder of the cavity-defining structure material, the reflective cylinder having an axis of rotational symmetry parallel to the output light beam; and
reflective plates arrayed along the axis of rotational symmetry of the reflective cylinder, the reflective plates intersecting the reflective cylinder,
a material filling interstices in the cavity-defining structure, the material having a second dielectric constant different from the first dielectric constant.
14. The surface-emitting laser of claim 13 , in which:
the reflective cylinder is a first reflective cylinder; and
the cavity-defining structure additionally comprises at least one additional reflective cylinder arranged concentrically with the first reflective cylinder and intersecting with the reflective plates.
15. The surface-emitting laser of claim 13 , in which:
the reflective cylinder and a pair of the reflective plates collectively define a central cavity; and
fewer of the reflective plates are disposed along the axis of rotational symmetry in one direction relative to the central cavity than in the opposite direction.
16. A method generating coherent light, the method comprising:
providing a layer structure, the layer structure comprising an optically-resonant cavity;
externally of the layer structure, generating excitation light having a single optical mode in a direction parallel to a major surface of the layer structure, the excitation light having an evanescent field associated therewith;
coupling part of the excitation light to the optically-resonant cavity via the evanescent field; and preferentially emitting the received excitation light from the optically-resonant cavity in a direction orthogonal to the major surface.
17. The method of claim 16 , in which generating the excitation light includes generating the excitation light by stimulated emission.
18. The method of claim 16 , in which preferentially emitting the received excitation light includes emitting the received excitation light in an axially asymmetric radiation pattern.
19. The method of claim 18 , in which, in providing an optically-resonant cavity, an optically-resonant cavity structured to be optically resonant at the wavelength of the excitation light and having an axially-asymmetric containment characteristic is provided.
20. The method of claim 19 , in which the method additionally comprise locating the optically-resonant cavity at a distance from the excitation light of less than the wavelength of the excitation light.
21. The method of claim 16 , in which generating the excitation light includes:
providing one-dimensional distributed Bragg reflectors; and
using the one-dimensional distributed Bragg reflectors to impose the single optical mode on the excitation light.
22. The method of claim 16 , in which generating the excitation light includes:
providing a diffraction grating; and
using the diffraction grating to impose the single optical mode on the excitation light.