# US 7,609,743 B2 · Volume Bragg lasers based on high efficiency diffractive elements in photo-thermo-refractive glass

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- Number: US 7,609,743 B2
- Document ID: US7609743B2
- Status: Granted
- Kind: B2
- Application number: 11/977,794
- Filed: 2007-10-26
- Published: 2008-04-03
- Granted: 2009-10-27
- Earliest claimed: 2004-04-27
- Assignees: University of Central Florida Research Foundation, Inc.
- Inventors: Leonid B. Glebov; Vadim I. Smirnov; George Venus
- Web page: https://patentgrep.com/patent/US7609743B2

## CPC

- H01S 3/08045: Single-mode emission
- H01S 3/08009: {using a diffraction grating}
- H01S 3/08036: using intracavity dispersive, polarising or birefringent elements
- H01S 3/0816: {having 4 reflectors, e.g. Z-shaped resonators}
- H01S 3/083: Ring lasers {(fibre ring lasers H01S3/06791)}
- H01S 5/141: {using a wavelength selective device, e.g. a grating or etalon (H01S5/146 takes precedence)}
- H01S 5/4006: {Injection locking}
- H01S 5/4062: {with an external cavity or using internal filters, e.g. Talbot filters}
- H01S 5/4068: {with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers}
- H01S 2301/20: Lasers with a special output beam profile or cross-section, e.g. non-Gaussian
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

A volume Bragg laser including a resonator comprising photo-thermo-refractive (PTR) volume diffractive elements that can be used in a laser emitting window of transparency of PTR glass to provide control of the lasers spectral and angular parameters, and methods, devices, apparatus and systems related thereto. The high efficiency volume Bragg gratings recorded in photo-thermo-refractive (PTR) glass preferably has an absolute diffraction efficiency exceeding approximately 95% in transmitting and reflecting modes is used for selection of a transverse and longitudinal mode for thermal, optical and mechanical stabilization of the volume Bragg lasers and coherent coupling of different lasers. Robustness, compactness, thermal and laser stability along with the ability to place several elements in the same space allows the use of sophisticated optical system according to the invention in fields of military lasers, optical communications, data storage and processing, and the like.

## Claims

### Claim 1

A resonator for a laser comprising:
a photo-thermo-refractive (PTR) volume diffractive element having a high absolute diffraction efficiency to provide angular selectivity and spectral selectivity; and
a collimating optics between the laser and the volume diffractive element for divergence of a laser radiation emitted from a gain medium of the laser, wherein said emitted radiation is directed toward said TPR volume diffractive element to provide control of at least one of a spectral and an angular parameter of the laser radiation;
wherein a transverse mode grating to provide said angular selectivity, wherein said transverse mode grating provides a significant difference in losses for the transverse mode grating with adjacent numbers and said collimator provides divergence of said radiation;
wherein a reflecting volume Bragg grating to provide said spectral selectivity, wherein said longitudinal mode grating is selected to provide significant difference in losses for longitudinal mode gratings with adjacent numbers and said collimating lens equalizes divergence of the laser beam along an orthogonal direction.

### Claim 2 (depends on 1)

The resonator of claim 1 further comprising:
a re-focusing element to provide further adjustment of a mode divergence and said angular selectivity.

### Claim 3 (depends on 1)

The resonator of claim 1 further comprising:
a dispersive element to provide sharpening of said spectral selectivity.

### Claim 4 (depends on 1)

The resonator of claim 1 further comprising:
mirror for reflecting a complementary radiation back to said PTR volume diffractive element.

### Claim 5 (depends on 4)

The resonator of claim 4 wherein said mirror is a reflecting PTR Bragg grating having a reflection coefficient exceeding approximately 95%.

### Claim 6 (depends on 1)

The resonator of claim 1 wherein said absolute diffraction efficiency exceeds approximately 95%.