Apparatus and methods for altering a characteristic of light-emitting device
Apparatus and methods for altering one or more spectral, spatial, or temporal characteristics of a light-emitting device are disclosed. Generally, such apparatus may include a volume Bragg grating (VBG) element that receives input light generated by a light-emitting device, conditions one or more characteristics of the input light, and causes the light-emitting device to generate light having the one or more characteristics of the conditioned light.
1. Apparatus for altering a characteristic of a light-emitting device, the apparatus comprising:
a light-emitting device having an emission spectrum;
a cylindrical microlens that receives light emitted by the light-emitting device; and
a three-dimensional optical element comprising a bulk of optical material and having a Bragg grating recorded in the bulk of optical material,
wherein the three-dimensional optical element receives light directed from the microlens, the light received by the optical element having a first bandwidth, and redirects only a narrowband portion of the light received from the microlens, the redirected narrowband portion having a second bandwidth that is narrower than the first bandwidth, such that the redirected narrowband portion is fed back optically into the light-emitting device as a narrow-wavelength seed that causes a narrowing of the emission spectrum of the light-emitting device, and wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens collimates the light emitted by the light-emitting device along the fast axis of the light-emitting device.
2. Apparatus according to claim 1 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens reduces divergence of the light emitted by the light-emitting device along the fast axis of the light-emitting device.
3. Apparatus according to claim 1 , wherein the three-dimensional optical element provides external feedback to the light-emitting device.
4. Apparatus according to claim 1 , wherein the lens has a focal length in the range of about 0.05 mm to about 3.0 mm.
5. Apparatus according to claim 1 , wherein the three-dimensional optical element has a thickness in a range from about 0.2 mm to about 3.0 mm, and a reflectivity in a range from about 5 percent to about 60 percent.
6. Apparatus according to claim 1 , wherein the three-dimensional optical element is positioned at a distance behind the microlens, the distance being in a range from about 0 mm to about 10 mm.
7. Apparatus according to claim 1 , wherein the microlens is formed on or attached to a surface of the three-dimensional optical element thus forming an integral optical element.
8. Apparatus according to claim 1 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens does not collimate the light emitted by the light-emitting device along the slow axis of the light-emitting device.
9. Apparatus according to claim 1 , wherein the microlens does not collimate the light emitted by the light-emitting device along the slow axis of the light-emitting device.
10. Apparatus according to claim 9 , further comprising a second microlens that collimates the light emitted by the light-emitting device along the slow axis of the light-emitting device.
11. Apparatus for altering a characteristic of a light-emitting device, the apparatus comprising:
a laser having a laser cavity and an emission spectrum;
a cylindrical microlens that receives laser light emitted by the laser, the emitted laser light having a first bandwidth; and
a light-conditioning element comprising a three-dimensional Bragg grating element having a holographic Bragg grating recorded therein,
wherein the light-conditioning element receives laser light directed from the microlens, and
wherein the laser operates above threshold in the absence of the feedback, and the Bragg grating is adapted to redirect a portion of the laser light received from the microlens, the redirected portion of the laser light having a second bandwidth that is narrower than the first bandwidth, such that the redirected portion is fed back optically into the laser cavity as a narrow wavelength seed that causes a narrowing of the emission spectrum of the laser.
12. Apparatus according to claim 11 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens collimates the light emitted by the light-emitting device along the fast axis of the light-emitting device.
13. Apparatus according to claim 11 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens reduces divergence of the light emitted by the light-emitting device along the fast axis of the light-emitting device.
14. Apparatus according to claim 11 , wherein the three-dimensional optical element provides external feedback to the light-emitting device.
15. Apparatus according to claim 11 , wherein the microlens is formed on or attached to a surface of the three-dimensional optical element thus forming an integral optical element.
16. Apparatus according to claim 11 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens does not collimate the light emitted by the light-emitting device along the slow axis of the light-emitting device.
17. Apparatus according to claim 11 , wherein the light emitting device has a fast axis and a slow axis, and wherein the microlens does not collimate the light emitted by the light-emitting device along the fast axis of the light-emitting device.
18. Apparatus according to claim 12 , wherein the microlens does not collimate the light emitted by the light-emitting device along the slow axis of the light-emitting device.
19. Apparatus according to claim 11 , further comprising a second microlens that collimates the light emitted by the light-emitting device along the slow axis of the light-emitting device.