Analog external cavity laser

• US 20050281298A1
• Filed: 04/01/2005
• Published: 12/22/2005
• Est. Priority Date: 04/02/2004
• Status: Abandoned Application

• Current Assignee: Emcore Corporation
• Original Assignee: K2 Optronics, Inc. (Emcore Corporation)
• Inventors: Kupershmidt, Vladimir, Major, John, Siala, Sabeur, Kusnadi, Frans
• Application Number:
  US11/097,745
• Publication Number:
  US 20050281298A1
• Time in Patent Office: Days
• US Class Current: 372/34
• CPC Class Codes: H01S 2301/03 Suppression of nonlinear conversion, e.g. specific design to suppress for example stimulated brillouin scattering [SBS], mainly in optical fibres in combination with multimode pumping
• CPC Class Codes: H01S 3/1055 one of the reflectors being constituted by a diffraction grating
• CPC Class Codes: H01S 3/1398 by using a supplementary modulation of the output
• CPC Class Codes: H01S 5/0064 Anti-reflection components, e.g. optical isolators
• CPC Class Codes: H01S 5/0078 for frequency filtering
• CPC Class Codes: H01S 5/02216 Butterfly-type, i.e. with electrode pins extending horizontally from the housings
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/02415 by using a thermo-electric cooler [TEC], e.g. Peltier element
• CPC Class Codes: H01S 5/02438 Characterized by cooling of elements other than the laser chip, e.g. an optical element being part of an external cavity or a collimating lens
• CPC Class Codes: H01S 5/028 Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
• CPC Class Codes: H01S 5/0427 for applying modulation to the laser
• CPC Class Codes: H01S 5/06804 by monitoring an external parameter, e.g. temperature
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/141 using a wavelength selective device, e.g. a grating or etalon H01S5/146 takes precedence
• CPC Class Codes: H01S 5/147 having specially shaped fibre, e.g. lensed or tapered end portion
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4062 with an external cavity or using internal filters, e.g. Talbot filters
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

The present invention relates to the analog external cavity lasers (ECLs) including designs, materials, methods of manufacturing and methods of use for such ECLs and packages for such ECLS. Numerous criteria are presented that lead to improved cost/performance for ECLs and for systems incorporating such ECLs.

Claims

1. An analog external cavity laser comprising:

a) a light source having a reflective back facet, a transmissive front facet; and

,

b) a partially reflective feedback element forming a laser cavity in cooperation with said reflective back facet; and

,

c) one or more temperature controllers maintaining the operating temperature of said laser at least a few degrees Celsius away from a mode hop.

2. An analog external cavity laser as in claim 1 wherein said reflective back facet has a reflectivity exceeding about 75%.

3. An analog external cavity laser as in claim 1 further comprising an anti-reflective coating on said front facet wherein said anti-reflective coating has a reflectivity less than about 0.05%.

4. An analog external cavity laser as in claim 1 wherein said light source is a Fabry-Perot gain element having an active length from about 300 micrometers to about 500 micrometers.

5. An analog external cavity laser as in claim 1 wherein said feedback element is a fiber Bragg grating.

6. An analog external cavity laser as in claim 1 wherein said feedback element has a reflectivity from approximately 5% to approximately 25%.

7. An analog external cavity laser as in claim 1 wherein said light source has a symmetrical far-field beam profile.

8. An analog external cavity laser as in claim 1 wherein said laser cavity has a linewidth enhancement factor at the wavelength of the gain peak of said light source less than about 4.

9. An analog external cavity laser as in claim 1 wherein the ratio of mode spacing to the bandwidth of said feedback element is from approximately 0.5 to approximately 1.3.

10. An analog external cavity laser as in claim 1 wherein the side-lobe suppression of said feedback element exceeds about 15 dB.

11. An analog external cavity laser as in claim 5 wherein said fiber Bragg grating is an apodized grating.

12. An analog external cavity laser as in claim 5 further comprising a microlens on the tip of the fiber containing said fiber Bragg grating.

13. An analog external cavity laser as in claim 1 further comprising an in-line optical isolator.

17. An analog external cavity laser as in claim 1 wherein said analog external cavity laser has blue detuning from about 20 nanometers to about 50 nanometers.

14. A method of suppressing stimulated Brillouin scattering in an analog external cavity laser comprising modulating the effective light path within the laser cavity.

15. A method of reducing frequency tilt in an analog external cavity laser comprising reducing the dispersive nature of the feedback element of said analog external cavity laser.

16. A method as in claim 15 wherein said method comprises at least one of:

a) using a large bandwidth fiber Bragg grating as said feedback element in the range from approximately 220 picometers to approximately 450 picometers full width at half maximum; and

,

b) using a non-apodized fiber Bragg grating as said feedback element; and

,

c) using a chirped fiber Bragg grating as said feedback element with appropriate direction to substantially cancel dispersion effects in said grating.

18. A method of operating an analog external cavity laser comprising operating said analog external cavity laser under a detuned loading condition such that the slope of the efficiency curve peaks around the threshold current, then decreases as the bias current is increased to reach substantially a minimum value approximately at the desired optical output power, then increases with further increase in said bias current.