APPARATUS AND METHODS USING HOLLOW-CORE FIBER TAPERS

• US 20100296093A1
• Filed: 05/11/2010
• Published: 11/25/2010
• Est. Priority Date: 07/25/2006
• Status: Active Grant

• Current Assignee: Aydogan Ozcan, Michel J.F. Digonnet
• Original Assignee: Aydogan Ozcan, Michel J.F. Digonnet
• Inventors: Digonnet, Michel J.F., Ozcan, Aydogan
• Granted Patent: US 8,009,948 B2
• Time in Patent Office: Days
• US Class Current: 356/432
• CPC Class Codes: G02B 6/02052 comprising optical elements other than gratings, e.g. filters comprising gratings G02B6/02057
• CPC Class Codes: G02B 6/02304 Core having lower refractive index than cladding, e.g. air filled, hollow core
• CPC Class Codes: G02B 6/02328 Hollow or gas filled core
• CPC Class Codes: G02B 6/02347 Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding
• CPC Class Codes: G02B 6/02376 Longitudinal variation along fibre axis direction, e.g. tapered holes
• CPC Class Codes: G02B 6/2552 reshaping or reforming of light guides for coupling using thermal heating, e.g. tapering, forming of a lens on light guide ends

Abstract

An optical device and methods of using an optical device are provided. The optical device includes a hollow-core fiber including a first portion and a second portion. The first portion includes a hollow core having a first diameter. The second portion includes a hollow core having a second diameter smaller than the first diameter. The difference between the first diameter and the second diameter is less than 10% of the first diameter.

Claims

1. An optical device comprising an optical fiber, the optical fiber comprising a first optical fiber portion comprising a hollow core having a first diameter, the optical fiber further comprising a second optical fiber portion comprising a hollow core having a second diameter smaller than the first diameter, wherein the difference between the first diameter and the second diameter is less than 10% of the first diameter.

2. The optical device of claim 1, wherein the first optical fiber portion comprises a first photonic-crystal cladding having a third diameter, and the second optical fiber portion comprises a second photonic-crystal cladding having a fourth diameter smaller than the third diameter.

3. The optical device of claim 1, wherein the difference between the first diameter and the second diameter is less than 2% of the first diameter.

4. The optical device of claim 1, wherein the optical fiber has a tapering ratio of less than 2%.

5. The optical device of claim 1, wherein the optical fiber has a tapering ratio of less than 10%.

6. The optical device of claim 1, wherein the optical fiber further comprises a tapered optical fiber portion between the first optical fiber portion and the second optical fiber portion, the tapered optical fiber portion comprising a hollow core with a monotonically-varying diameter.

7. The optical device of claim 1, wherein the optical fiber further comprises a third optical fiber portion having a hollow core having a fifth diameter larger than the second diameter, the second optical fiber portion between the first optical fiber portion and the third optical fiber portion.

8. The optical device of claim 7, wherein the fifth diameter is substantially equal to the first diameter.

9. The optical device of claim 7, wherein the optical fiber further comprises a tapered optical fiber portion between the second optical fiber portion and the third optical fiber portion, the tapered optical fiber portion comprising a hollow core having a monotonically-varying diameter.

10. The optical device of claim 1, wherein the optical device comprises an optical filter having a transmission spectrum in a selected range of wavelengths, the transmission spectrum having modulations with a modulation period in a range between about 0.5 and about 3.3 nanometers.

11. The optical device of claim 1, where both the first optical fiber portion and the second optical fiber portion are transmissive to light having a first range of wavelengths, and the first optical fiber portion is transmissive to light having a second range of wavelengths, wherein the second optical fiber portion is not transmissive to the light having the second range of wavelengths.

12. The optical device of claim 1, wherein the hollow core of the second portion is configured to receive a specimen, the specimen comprising one or more chemicals or biological materials, wherein a transmission spectrum of the optical device is indicative of the presence of a predetermined molecule or molecular species in the specimen.

13. A method of forming an optical fiber, the method comprising:

providing a hollow-core fiber, the hollow-core fiber comprising a first portion, a second portion, and a third portion positioned between the first portion and the second portion, the third portion having a first diameter;

heating at least the third portion of the hollow-core fiber to a temperature at which the third portion is plastically deformable;

pulling at least one of the first portion and the second portion such that a distance between the first portion and the second portion increases, thereby stretching and plastically deforming the third portion such that the third portion has a second diameter less than the first diameter, wherein pulling is stopped before the difference between the second diameter and the first diameter is greater than 10% of the first diameter; and

allowing the hollow-core fiber to cool and set.

14. A method of filtering an optical signal, the method comprising:

providing an optical fiber comprising;

a first portion comprising a hollow core having a first diameter; and

a second portion comprising a hollow core having a second diameter smaller than the first diameter, wherein the difference between the first diameter and the second diameter is less than 10% of the first diameter; and

transmitting an optical signal through the first portion of the optical fiber to the second portion of the optical fiber, wherein a first portion of the optical signal having a first range of wavelengths is transmitted through the second portion of the optical fiber and a second portion of the optical signal having a second range of wavelengths is not transmitted through the second portion of the optical fiber.

15. The method of claim 14, wherein the optical fiber further comprises a third portion having a hollow core having a third diameter larger than the second diameter, and the method further comprises transmitting a portion of the second portion of the optical signal through the third portion of the optical fiber, wherein the portion of the second portion of the optical signal has a third range of wavelengths.

16. A laser system comprising:

a hollow-core fiber comprising;

a first optical fiber portion comprising hollow core having a first diameter;

a second optical fiber portion comprising a hollow core having a second diameter smaller than the first diameter; and

a third optical fiber portion having a hollow core having a third diameter larger than the second diameter;

two optical reflectors bounding an optical resonating region, wherein the second optical fiber portion is within the optical resonating region; and

a gain medium in the optical resonating region, wherein the hollow-core fiber is in optical communication with the gain medium.

17. The laser system of claim 16, wherein the difference between the first diameter and the second diameter is less than 10% of the first diameter.

18. A method of generating laser light, the method comprising:

providing a hollow-core fiber comprising;

a first optical fiber portion comprising a hollow core having a first diameter;

a second optical fiber portion comprising a hollow core having a second diameter smaller than the first diameter, the second optical fiber portion in an optical resonating region having a fundamental mode spectrum; and

a third optical fiber portion having a hollow core having a third diameter larger than the second diameter;

providing a gain medium in the optical resonating region, the gain medium in optical communication with the hollow-core fiber; and

using the hollow-core fiber to filter light from the gain medium by removing light having one or more wavelengths different from the fundamental mode spectrum.

19. The method of claim 18, wherein the difference between the first diameter and the second diameter is less than 10% of the first diameter.

20. A method of sensing the presence of one or more chemicals or biological materials in a specimen, the method comprising:

providing a hollow-core fiber comprising;

a first portion comprising a hollow core having a first diameter;

a second portion comprising a hollow core having a second diameter smaller than the first diameter, wherein the difference between the first diameter and the second diameter is less than 10% of the first diameter; and

a third portion having a hollow core having a third diameter larger than the second diameter;

inserting the specimen into the hollow-core fiber; and

detecting a transmission spectrum of the hollow-core fiber while the specimen is within the hollow-core fiber, wherein the transmission spectrum is indicative of the presence of a predetermined molecule or molecular species in the specimen.