Laser with electrically-controlled grating reflector

• US 5,504,772 A
• Filed: 09/09/1994
• Issued: 04/02/1996
• Est. Priority Date: 09/09/1994
• Status: Expired

• Current Assignee: Gemfire Corp. (Medtronic Plc)
• Original Assignee: Deacon Research
• Inventors: Bischel, William K., Field, Simon J., Brinkman, Michael J., Deacon, David A. G.
• Primary Examiner(s): LEE, JOHN D
• Assistant Examiner(s): LEE, JOHN D
• Application Number:
  US08/303,801
• Time in Patent Office: 571 Days
• Field of Search: 372/6, 372/12, 372/37, 372/102, 385/8, 385/10
• US Class Current: 372/102
• CPC Class Codes: G02F 2201/30 grating
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/063 Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength waveguide gas lasers H01S3/0315
• CPC Class Codes: H01S 3/0635 provided with a periodic structure, e.g. using distributed feed-back, grating couplers controlling, e.g. modulating distributed feed-back lasers H01S3/102
• CPC Class Codes: H01S 3/1055 one of the reflectors being constituted by a diffraction grating
• CPC Class Codes: H01S 3/108 using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering mode locking using a non-linear element H01S3/1112
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• 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 5/4062 with an external cavity or using internal filters, e.g. Talbot filters

Abstract

One or more lasers are combined with optical energy transfer devices and energy guiding devices which use an electric field for control. The optical energy transfer devices may form gratings, mirrors, lenses and the like using a class of poled structures in solid material. The poled structures may be combined with waveguide structures. Electric fields applied to the poled structures control routing, reflection and refraction of optical energy. Adjustable tunability is obtained by a poled structure which produces a spatial gradient in a variable index of refraction along an axis in the presence of a variable electric field.

Claims

1. A laser comprising:

a solid material for passing optical energy;

at least a first electrically-conductive material forming a first electrode, said first electrode confronting said solid material and bridging at least two elements of an electrically-controllable grating structure in said solid material;

an optical amplifier disposed along an optical axis, said optical axis traversing said solid material, said at least two elements being disposed transverse of said optical axis; and

an optical coupling means disposed between said solid material and said optical amplifier along said optical axis.

2. The device according to claim 1 further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material.

3. The device according to claim 1 further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material;

waveguide means along said optical axis in said solid dielectric material, wherein said optical amplifier is a semiconductor diode;

wherein

said optical coupling has butt coupling and antireflective means disposed between said semiconductor diode and said waveguide; and

wherein

said at least two elements form a feedback mirror capable of producing laser oscillation.

4. The device according to claim 1 further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material;

a modulation controller for modulating said electric field creating means;

said optical coupling being antireflective to inhibit laser oscillation in absence of said electric field; and

wherein said grating is a field-controlled feedback mirror for producing laser oscillation in proportion to the strength of said electric field.

5. The device according to claim 4 for amplitude modulation of an optical signal, wherein said grating comprises alternates of said first type of said elements with a second type of said elements, said second type being a poled structure having a reverse sense to said first type of said elements and wherein average optical distance across said first type of elements is substantially equal to average optical distance across said second type of elements along said optical axis.

6. The device according to claim 4 for frequency modulation of an optical signal, wherein said grating comprises alternating said first type of said elements with a second type of said elements, said second type being a poled structure having a reverse sense to said first type of said elements and wherein average optical distance across said first type of elements differs from average optical distance across said second type of elements along said optical axis.

7. The device according to claim 1 for mode locking optical energy, further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material; and

a mode locker operated at a frequency that is a multiple of a frequency which is the reciprocal of the round-trip optical transit time between said grating and said optical reflector.

8. The device according to claim 1 wherein said at least two elements are formed from a plurality of types of domains having a plurality of electro-optic coefficients, and further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material;

wherein said optical coupling means is antireflective to inhibit laser oscillation in absence of optical feedback from said at least two elements; and

wherein the sum over all domain types of the product, for each domain type, of said electro-optic coefficient times the average distance across the domain type along said optical axis, differs from zero.

9. The device according to claim 1, for nonlinear conversion of optical energy, further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material;

wherein said solid dielectric material further includes a pattern of differing domains transverse to said optical axis, at least a first type of said domains being an optically nonlinear structure and forming a plurality of components alternating with a second type of said domains, said pattern being phase matched to interact between three optical waves of at least two different frequencies, wherein a linear combination of the values of the frequencies of said three optical waves is substantially zero to generate at least one optical output beam.

10. The device according to claim 9, wherein said elements and said components together form a combined structure with both reflecting and nonlinear optical properties.

11. The device according to claim 9 wherein said optically nonlinear structure is a frequency doubler.

12. The device according to claim 9 wherein said optically nonlinear structure is a frequency mixer.

13. The device according to claim 9 wherein said optically nonlinear structure is an optical parametric oscillator frequency doubler.

14. The device according to claim 1, wherein said grating comprises alternates of said first types of said elements and second types of said elements which are spaced at at least two different periods.

15. The device according to claim 1 further including:

an optical reflector disposed along said optical axis, said optical amplifier being disposed between said optical reflector and said solid dielectric material; and

at least one electro-optically active region in said solid material transverse of said optical axis and having an electrode adjacent said active region for inducing an electric field.

16. The device according to claim 15 wherein said active region defines an optical focussing device.

17. The device according to claim 15 wherein said active region has a reflective interface at a skew with said optical axis and forms a reflecting grating for diverting optical energy.

18. The device according to claim 15 wherein said active region is a variable dispersion, electrically-controllable waveguide segment along said optical path.

19. A laser comprising:

a solid material for passing optical energy;

an input waveguide in said solid material;

a base reflector disposed along an optical axis;

a plurality of output waveguides encountering said input waveguide at intersection regions along said input waveguide;

a plurality of electrically-switchable beam redirectors disposed along said input waveguide at said intersection regions, each one of said electrically-switchable beam redirectors comprising a first electrically-conductive material forming a first electrode, said first electrode confronting said solid material and bridging at least one electrically-active element in said solid material;

a plurality of gratings disposed along said output waveguides defining electrically-selectable retroreflectors further defining cavities between said base reflectors and said gratings;

an optical amplifier disposed along an optical axis, said optical axis traversing said solid material; and

an optical coupling means disposed between said solid material and said optical amplifier along said optical axis.

20. The laser according to claim 19 wherein said electrically-switchable beam redirectors are total internal reflectors.

21. The laser according to claim 19 wherein said electrically-switchable beam redirectors are switchable minors.

22. The laser according to claim 19 wherein said gratings have differing periods in order to support selectable-frequency operation.