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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 17, Iss. 14 — Jul. 6, 2009
  • pp: 12057–12069
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Reduction of the time-to-full-brightness in solid-state lasers using intra-cavity adaptive optics

Walter Lubeigt, Mike Griffith, Leslie Laycock, and David Burns  »View Author Affiliations


Optics Express, Vol. 17, Issue 14, pp. 12057-12069 (2009)
http://dx.doi.org/10.1364/OE.17.012057


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Abstract

Several adaptive-optics techniques, based on the active modification of the optical properties of the laser cavity, were used to significantly reduce the time-to-full-brightness of solid-state lasers. Resonator re-configuration was achieved using a mechanical translation stage and both multi- and single-element deformable bimorph mirrors. Using these techniques the effects of thermally induced distortion in Nd:YLF and Nd:YAG lasers can be minimized and the warm-up time reduced by a factor of 3–6.

© 2009 OSA

1. Introduction

At the turn-on of a solid-state laser, the build-up of heat within the laser crystal prevents the maximum brightness from being obtained until a thermal equilibrium state is reached. As the laser is typically aligned with reference to the hot state, then in the transient turn-on phase, the laser characteristics, specifically the brightness, is non-optimal. For some applications, and particularly for military use, the time taken to reach full brightness is a critical parameter and considered a major limitation in existing systems. This time, governed by the evolution of the temperature distribution within the gain medium, can vary greatly depending on parameters such as the pumping and cooling arrangement, the details of the laser cavity configuration, and, the nature of the gain medium. A characteristic time – the time-to-full-brightness (TTFB) – defined as the time taken to reach the hot equilibrium state can be in the order of a few seconds for typical Nd-based laser systems. However, for any given laser configuration the TTFB is consistent and reproducible.

The use of adaptive optics components within laser resonators has been shown to be effective in compensating for thermally-induced aberrations; however, this has largely concentrated on steady-state control of the laser. Notably, Moshe et al obtained a zero warm-up time by using a movable lens/mirror combination inside the laser cavity [1

1. I. Moshe, S. Jackel, and R. Lallouz, “Working beyond the static limits of laser stability by use of adaptive and polarization-conjugation optics,” Appl. Opt. 37(27), 6415–6420 (1998). [CrossRef]

]. This system was effective, however, higher-order thermal lens correction, responsible for the reduction in efficiency and brightness, was not possible [2

2. J. W. Hardy, Adaptive Optics for Astronomical Telescope (Oxford University Press US, 1998), Chap. 6.6.

]. The intra-cavity use of deformable mirrors (particularly bimorph mirrors [3

3. A. V. Ikramov, I. M. Roshchupkin, and A. G. Safronov, “Cooled bimorph adaptive mirrors for laser optics,” Quantum Electron. 24(7), 613–617 (1994). [CrossRef]

,4

4. J. C. Dainty, A. V. Koryabin, and A. V. Kudryashov, “Low-order adaptive deformable mirror,” Appl. Opt. 37(21), 4663–4668 (1998). [CrossRef]

]) has the potential to control the laser output beam [5

5. T. Y. Cherezova, L. N. Kaptsov, and A. V. Kudryashov, “Cw industrial rod YAG:Nd3+ laser with an intracavity active bimorph mirror,” Appl. Opt. 35(15), 2554–2561 (1996). [CrossRef]

]. Here, we report the use of a new type of large-stroke deformable bimorph mirror in reducing the TTFB in a range of Nd-based lasers. These bimorph mirrors - considerably more rugged than their deformable membrane counterparts - have been developed by BAE Systems ATC [6

6. BAE Systems Advanced Technology Centre, West Hanningfield rd, Great Baddow, Chelmsford CM2 8HN, UK.

]. Mirrors composed of an array of transducers to promote a complex mirror shape, or, a single actuator device providing only defocus correction are used here. The active aperture of these mirrors has a diameter of 18mm. A 0.3mm thick front layer of SiC is deposited on top of a 0.2mm thick PZT disk. This SiC front layer can be coated in order to achieve the high reflectivities (>99%) required for intra-cavity use.

Previously, a method to automatically enhance the brightness of a Nd:GdVO4 laser [7

7. W. Lubeigt, G. Valentine, J. Girkin, E. Bente, and D. Burns, “Active transverse mode control and optimization of an all-solid-state laser using an intracavity adaptive-optic mirror,” Opt. Express 10(13), 550–555 (2002).

,8

8. W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]

] using an intra-cavity deformable membrane mirror (DMM) from [9

9. B. V. Flexible Optical, PO Box 581, 2600 AN, Delft, the Netherlands, www.okotech.com

], a brightness sensor and a pc-based control algorithm has been developed. This system resulted in a brightness enhancement by an order of magnitude [8

8. W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]

] and could automatically address subtle changes in operating conditions such as alignment and temperature variations. However, the iterative control scheme used resulted in an optimisation time on the order of tens of seconds, or more. Such a scheme is therefore limited to steady-state optimisation of laser performance and not relevant for fast TTFB laser control. Additionally, the stroke of the DMM (maximum ~5µm) is, in general, inadequate to fully compensate for the large thermal lens variations at the turn-on of the laser.

A simple look-up table approach, based on applying pre-determined mirror transducer voltages as time progresses, is one way to ensure that the control system efficiently compensates for the rapidly changing thermal lens. These values should reflect the nature of the laser cavity elements (their position, focal length etc) such that they can be changed during the transient phase to ensure that the size of the fundamental mode in the gain medium remains constant. In this way, the laser mode can be stabilised even though the laser rod exhibits a largely varying lens. Therefore, a thorough thermal lens study must be performed in order to calculate the adequate pre-determined values for the mirror curvature. Therefore, using a multi-element deformable mirror to reduce the warm-up time enables both the transient and steady-state optimisations to be successively performed on the same laser.

In the first instance, a test laser platform based on a 63mm long side-pumped Nd:YLF rod was configured. An analysis of the properties of the induced thermal lens throughout the transient phase was first undertaken using finite element modelling in order to calculate the look-up table values. To test the viability of the concept, a movable cavity mirror mounted on a mechanical translation stage was configured to reduce the TTFB. A similar experiment using a multi-channel deformable mirror was also performed. Finally, a single-actuator deformable mirror was used to control the TTFB of an end-pumped Nd:YAG laser.

Section 2 introduces the transient optimisation strategy undertaken including an analysis of the pump-induced thermal lensing in the Nd:YLF rod. Section 3 describes the experimental work using the mechanical translation stage, and the large-stroke multi-actuator deformable mirror. Finally, section 4 will present the transient optimisation of a Nd:YAG laser using a single-actuator deformable mirror.

2. Control strategy

The non-uniform temperature distribution within the laser rod resulting from pumping leads, as a consequence of the temperature dependence of the refractive index, to the production of a thermally-induced lens [10

10. W. Koechner, Solid-State Laser Engineering, 5th edition (Springer Series in Optical Sciences, New-York, 1999)

]. This thermal lens significantly modifies the optical properties of the laser resonator and therefore, one method of reducing the TTFB of the laser is to correspondingly adapt the properties of the optical resonator during the transient turn-on period. To establish the necessary changes, a study of the thermal lens at steady-state in the gain medium must be undertaken - in this way, the look-up table correction value can be obtained.

Such a measurement can be undertaken by observing the changes made to a probe beam, however, finite element modelling can be a powerful tool in revealing both the aberrations and the time dependence of the induced lensing. In the following sub-sections a study of the thermal lens will be detailed; direct thermal lens measurement will be reported; and, the results of finite element analysis revealing the transient properties of the induced lens will be described.

2.1 Thermal lens study

The test laser system consisted of a commercially-available Nd:YLF module from CEO [11

11. Cutting Edge Optronics, Cutting Edge Optronics, 20 Point West Boulevard, St. Charles, MO 63301, USA, http://www.st.northropgrumman.com/ceolaser/.

] based on a 63mm long, 3mm diameter, a-cut, 0.9% Nd-doped rod. The rod is pumped by three groups of three diode laser bars resulting in a total pump power of 180W. The rod was water-cooled on its barrel surface. Using the finite-element analysis model native to the commercial software package LASCAD [12

12. L. A. S. C. A. D. Gmbh, Brimhildenstr. 9, 80639 Munich, Germany, http://www.las-cad.com/index.php.

], the pump deposition and temperature distribution within the gain medium could be obtained and are displayed in Fig. 1. The Nd:YLF parameters used in the model correspond to the case of a Nd:YLF rod cut along the a-axis emitting light polarised along the c-axis (i.e. π-polarisation) and are given in Table 1. It is immediately obvious that the pumping configuration results in an almost uniform pump deposition, with this being encouraged by retro-reflection of unabsorbed pump light back into the rod.

Table 1. The Nd:YLF parameters used in the finite-element analysis

table-icon
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Using the calculated temperature distribution, an approximation of the resulting focal length of the thermal lens could be obtained: the average temperature along the longitudinal axis (z in Fig. 1) of both x and y axes were used and the change in refractive index leading to the thermal lens was calculated. In this way, the focal lengths obtained from these data were -2.1m and -1m for the x and y axes respectively (N.B. these axes are parallel and perpendicular to the crystal c-axis respectively). The maximum displacement of the material along z-axis was found to be around 1.6µm, and so the bulge at the rod ends can be neglected.

Fig. 1. Temperature distribution in the rod (a), pump deposition (b) and temperature (c) distributions in the cross section located at the centre of the rod

2.2 Experimental measurement of the thermal lens

Fig. 2. Experimental set-up used for thermal lens measurement

As expected, for both polarisations, the thermal lens was found to be cylindrical. For light polarised along the c-axis of the YLF rod (i.e. the π-polarisation), the measured focal length was -0.7m perpendicular to the c-axis and -2.1m parallel to the c-axis.

For incident light polarised perpendicular to the c-axis of the rod (the σ-polarisation) the measured focal lengths were -5m and +7m perpendicular and parallel to the c-axis of the rod respectively. [In Nd:YLF, π- and σ-polarisations correspond to laser oscillation at 1047 and 1053nm respectively.] The cylindricity in the thermal lens leads to astigmatism which can be compensated through cavity design, however, this is more challenging than in the case of circularly symmetric deformations as would be the case with, say, Nd:YAG.

In further experiments the laser was configured to operate on the π-polarisation at 1047nm, this allows an evaluation of the concept of using an active element to compensate for a significant, but rapidly varying thermal lens. The focal length values of -0.7 and -2.1m were used to populate the look-up table required for transient optimisation - these measured values agree well with our modelled values from section 2.1 but more accurately reflect the real system used in the experiments.

2.3 Transient thermal lens

Since the object of this study was to determine a technique to reduce the TTFB of the laser, it is important to assess the temperature build-up within the gain medium leading to the establishment of the steady-state thermal lens. Using the FEA-based software (Comsol Multiphysics [13

13. COMSOL Multiphysics, COMSOL Inc., 1 New England Executive Park, Suite 350, Burlington, MA 01803, USA.

]), the time dependence of the temperature at the centre of the rod was calculated and is shown in Fig. 3. The model used a 2.5 second duration square-shaped input pump having a power of 180W.

The maximum temperature increase obtained of just over 10K evaluated from the model was consistent with that measured previously using the LASCAD software. From this time dependent model, it can clearly be seen that the majority (>90%) of the temperature rise occurs within the first 500ms, the temperature reaching the steady-state within approximately 1.2s. The transient optimisation scheme must then track the thermal lens changes over this timescale – further evidence that iterative optimisation methods are inappropriate in this situation. Furthermore, ~1.5 second after the pump pulse is turned off, the temperature within the laser rod cools to the background level. This timescale for rod cooling was therefore much faster than the time between consecutive pump pulses, and so, it was assured that the rod had fully recovered between pump pulses.

Fig. 3. Calculated temperature dependence at the centre of the Nd:YLF rod

3. Transient optimisation system

3.1 Transient optimisation using a mechanical translation stage

A basic 2-mirror Nd:YLF laser was constructed where the output coupler was mounted on a mechanical translation stage – see schematic shown in Fig. 4. To assess the feasibility of transient optimisation, a simple technique based on the compensation of the first order component of the thermal lens was used and the laser cavity designed accordingly. Here the distance, d, between the output coupler and the laser crystal is varied such that the fundamental mode size within the laser rod remains constant over time. The initial (cold) and final (hot) values of d were calculated using the ray-matrix software Winlase [14

14. Winlase II, Future Laser Technologies, 5051 Alton Pkwy #102, Irvine, CA 92604, USA.

] and chosen to avoid any beam ellipticity induced by the astigmatic nature of the thermal lens. In this analysis, attention was given in maintaining high brightness operation of the laser, and to this end, the fundamental mode within the gain medium was made relatively large (~550µm with d=380mm). In practice, to ensure single transverse mode oscillation, the incorporation of an aperture was required. The resulting laser output was then single transverse mode at a power of ~6.5W. For the cold cavity, a plot of the fundamental transverse mode was calculated and is shown as Fig. 5(a).

A similar plot, taking into account the full thermal lens and an increased distance d, is shown in Fig. 5(b). From these data, at d=353mm, the fundamental mode radius was 562µm for the cold cavity, while, at d=386mm, mode radius is 540µm in the π-plane and 546µm in the σ-plane when the thermal lens is included. It is therefore apparent that a 33mm translation of the output coupler will ensure that both laser configurations have effectively the same beam parameters within the rod at the extremes of the thermal lens. The 3% difference in the calculated beam sizes lies within the accuracy of the thermal lens measurement (+/- 10%). Table 2 shows the variation of the mode size as function of d and the focal length of the thermal lens. From Table 2 and Fig. 5, it is clear that the beam size differs in both planes due to the cylindricity of the thermal lens induced in the Nd:YLF rod. This changes in the beam size also becomes more significant as the thermal lens increases.

Fig. 4. Test-bed laser cavity. The π plane is in the plane of the figure whereas the σ plane is perpendicular to the plane of the figure.
Fig. 5. Fundamental mode radius along the laser cavity (a) for the cold cavity (d=353mm) and (b) with the maximum thermal lens (d=386mm).

Table 2. Fundamental mode radius as a function of cavity length and focal length of the thermal lens

table-icon
View This Table
| View All Tables

The output coupler stage [15

15. MICOS VT-80, MICOS GmbH, Freiburger Str. 30, DE-79427 Eschbach, Germany.

] was addressed by a PC-based control program. The temperature dependence within the laser rod shown in Fig. 3, was used in conjunction with the optimal values of d to control the speed of the stage during the turn-on of the laser. The stage velocity profile should then mirror the time dependence of the thermal lens. However, in practice, due to the rapid turn-on of the laser, varying the stage speed to exactly match optimum profile was not possible, and so, the translation stage was set to its maximum velocity (~10cm/s) to provide appropriate optimisation.

Figure 6 shows the transverse intensity distribution of the laser output during the laser turn-on when (a) the mirror is fixed at d=353mm and (b) at d=386mm and (c) when the output coupler is moved from d=353mm to d=386mm. In the case of d=353mm, the output beam profiles quickly builds up to a single mode before degrading after about 0.3s into multi-transverse mode oscillation. This degradation is due to the decrease of the laser fundamental mode size within the gain medium as a consequence of the induced thermal lens. In the case of d=386mm, single transverse mode is maintained throughout, however, the full beam beam power is only obtained after ~0.4s at which the fundamental mode size reduces to the optimum value. For the case of the translating output coupler, a much better compromise results: the rapid high brightness state (typified by d=353mm) appears instantly and this is maintained over the whole transient turn-on period. The TTFB was then reduced from ~0.5s to below 0.1s. Some degree of astigmatism is evident, specifically around t~0.25s, due to the cylindricity of the thermal lens. Using an isotropic crystal such as Nd:YAG would, of course, eliminate this effect.

Fig. 6. Instantaneous transverse intensity distributions as a function of time after laser turn-on for (a) d=353mm, (b) d=386mm and (c) the output coupler moving at maximum speed from d=353mm to d=386mm.

Another variation of the laser cavity was configured as shown in Fig. 7. Using this folded cavity allowed the speed of the mirror translation to be effectively doubled and the required translation reduced to Δd~15mm. To represent output brightness, the intensity distribution of the output laser beam was apertured through a pinhole before being recorded by a photodiode. This measure of on-axis power gives a reasonable estimate of the output beam quality as it effectively discriminates between the fundamental laser mode and higher-order modes having a larger fraction of off-axis power. Again, the resulting profiles at the laser turn-on for the 3 different cases (fixed mirror optimised for (a) the cold cavity, (b) the full extent of the thermal lens, and (c) the moving compensating mirror) are shown in Fig. 8. The intensity recorded by the photodiode in Fig. 8(a), initially peaks, then reduces by about 20% before settling to a steady state after ~800ms. This is in contrast to the laser turn-on brightness profile of Fig. 8(b) which is characterised by a steady increase until at ~200ms when an equilibrium state is obtained. Finally, for the case of the translating mirror, the intensity remains essentially consistent throughout the full laser turn-on period. There is however, a slight discontinuity around t=200ms due to the rapid deceleration as the moving mirror comes to rest – this may possibly be eliminated by appropriate damping of the mirror/translation stage assembly.

Fig. 7. Folded laser cavity [N.B. the tangential plane is now along the σ-axis while the sagittal plane is along the π-axis]
Fig. 8. On-axis output power measured by a pinhole/photodiode arrangement for (a).d=170mm, (b) d=185mm and, (c) moving mirror laser

In conclusion, the moving method successfully reduced the TTFB of a Nd:YLF laser by approximately a factor of 5. Significant limitations were due, in this case, to the inability to compensate the astigmatism induced by the difference in thermal lens strength between the sagittal and tangential planes. Additionally, the precise velocity profile of the mechanical translation stage was found to be difficult to implement using the current apparatus. Using a variable speed during the optimisation (i.e. fast in the initial phase and slower for the final part) should increase the quality of the optimisation, however, even in the simple case used here, significant improvement was observed

3.2 Transient optimisation using a large stroke multi-element deformable mirror

Fig. 9. (a) View of the bimorph mirror, and (b) the corresponding actuator pattern where the actuator division is shown (160V and 100V were respectively applied to the actuators in green and in red)

Without correction, the free-running laser reached its optimum brightness in ~600ms. When the optimization scheme, as described above, was deployed, the resultant output displayed negligible astigmatism and the TTFB was reduced to ~200ms. The large stroke bimorph mirror therefore efficiently reduces the laser turn-on time, eliminates any astigmatic effects, and does not introduce any high-speed intensity modulation. As the bimorph mirror has a frequency response of ~6kHz, tracking between the extreme states of the laser can be achieved much more efficiently than possible with translating optics. This opens up the possibility of implementing this scheme in a wide range of lasers and temporal domains. The ability for the deformable mirror to track astigmatic cavity changes is a unique feature in this type of optimization scheme.

Fig. 10. Laser cavity with the IC deformable mirror
Fig. 11. Transverse intensity distribution at the turn-on time without (a) and with (b) transient correction of the bimorph mirror.

Finally, as has previously been demonstrated, such a large-stroke bimorph mirror can be employed to optimize the laser brightness in the steady-state regime [8

8. W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]

]. Therefore, the prospect of combining transient and steady-state optimization with a single correcting element is a distinct possibility. The maximum stroke afforded by this type of mirror (>20µm) in combination with careful cavity design and mirror position should make this technique valid for a wide range of high-power laser systems.

4. Transient optimization of a side-pumped Nd:YAG laser using a single-actuator deformable mirror

In this section, a single-element deformable mirror was used to reduce the TTFB of a Nd:YAG laser. The use of a single-element deformable mirror is motivated by the fact that the transient optimization is largely based on the compensation of the first order component of the thermal lens. The use of such a simple deformable mirror would obviously be inappropriate in laser cavities operating at higher powers and/or those having anisotropic gain media and featuring astigmatic optical elements. In these, more general cases, a multi-element deformable mirror should be used to define the initial and final mirror shapes, as described previously in section 3.2.

The deformable mirror, having a single actuator, could access a variable ROC in the range -1m to +10m. The surface of the mirror was coated with a quarter-wave dielectric stack having a reflectivity in excess of 99%. As the mirror only employs one transducer, then a much simpler control system is required.

Fig. 12. Schematic of the end-pumped Nd:YAG laser

The resulting laser optimization is shown in Fig. 13. In the case of the laser turn-on without mirror correction, the TTFB was measured to be ~630ms. With transient optimization, this value is reduced to ~90ms. Therefore, the single-element deformable mirror successfully reduced the TTFB by a factor of 6, and as expected, negligible astigmatism was observed. The very simple nature of the single-element mirror and its corresponding ease of control make this system potentially widely applicable in a variety of laser configurations, such as the rapid thermal lens compensation demonstrated here, but also in schemes to maintain resonator fidelity as components undergo significant axial motion. Furthermore, in contrast to the look-up table approach described here, a fast closed-loop scheme could be developed using a simple brightness or power sensor.

Fig. 13. Transverse intensity distribution at the turn-on time without (a) and with (b) transient correction of the bimorph mirror.

5. Conclusion

A range of methods for reducing the time-to-full-brightness (TTFB) at the turn-on of a laser have been successfully demonstrated. All three schemes were based on the active modification of the optical parameters of the laser resonator such that the fundamental mode-size within the laser rod remained constant during the turn-on phase. The build-up of the thermal lens within the gain medium of each laser platform was measured to be on the order of ~1s thus using of a closed-loop optimisation system is impractical. In the procedures discussed here, the optimisations of the TTFB were based on a look-up table approach based on knowledge of the thermal lens – the temporal dependence and measurement of the initial and final values.

The first system was based on physical translation of one of the intra-cavity mirrors (i.e. the output coupler). The test-laser platform was based on a 63mm long Nd:YLF rod and produced a single transverse mode power of 6.5W. During the translation, the TTFB was reduced to a value of ~50ms, and the optimal brightness was maintained over the full pump pulse. The limitations of this technique relate to the astigmatism of the thermal lens, the difficulty in adapting the mirror velocity profile to accurately track the thermal lens build-up, and also the high translation velocity required.

The second optimisation system was based on a large-stroke, 31-element, deformable bimorph mirror to optimise a laser cavity based on the same Nd:YLF rod. The laser output was 1.5W, and the TTFB was reduced by a factor of 3. Here, the effects of thermal lens astigmatism were significantly reduced as the mirror shape could be controlled and varied accordingly over time. Such mirrors pave the way for combined transient and steady-state aberration correction as it can be integrated into the automatic control loop schemes previously demonstrated [7

7. W. Lubeigt, G. Valentine, J. Girkin, E. Bente, and D. Burns, “Active transverse mode control and optimization of an all-solid-state laser using an intracavity adaptive-optic mirror,” Opt. Express 10(13), 550–555 (2002).

,8

8. W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]

].

In conclusion, we have demonstrated the efficacy of rapid thermal lens control based on maintaining the mode dimensions in the gain medium using resonator re-configuration using new large-stroke bimorph mirrors. It is clear that the characteristics of these devices make them suitable for rapid thermal lens control schemes where variations over tens of milliseconds can be effectively tracked. Furthermore, the large-stroke (20µm) allows for ROC at the dioptre level to be accommodated – an order of magnitude greater than their deformable membrane counterparts.

Acknowledgements

This work was funded by the UK Department of Trade and Industry under the INCAO project.

References and links

1.

I. Moshe, S. Jackel, and R. Lallouz, “Working beyond the static limits of laser stability by use of adaptive and polarization-conjugation optics,” Appl. Opt. 37(27), 6415–6420 (1998). [CrossRef]

2.

J. W. Hardy, Adaptive Optics for Astronomical Telescope (Oxford University Press US, 1998), Chap. 6.6.

3.

A. V. Ikramov, I. M. Roshchupkin, and A. G. Safronov, “Cooled bimorph adaptive mirrors for laser optics,” Quantum Electron. 24(7), 613–617 (1994). [CrossRef]

4.

J. C. Dainty, A. V. Koryabin, and A. V. Kudryashov, “Low-order adaptive deformable mirror,” Appl. Opt. 37(21), 4663–4668 (1998). [CrossRef]

5.

T. Y. Cherezova, L. N. Kaptsov, and A. V. Kudryashov, “Cw industrial rod YAG:Nd3+ laser with an intracavity active bimorph mirror,” Appl. Opt. 35(15), 2554–2561 (1996). [CrossRef]

6.

BAE Systems Advanced Technology Centre, West Hanningfield rd, Great Baddow, Chelmsford CM2 8HN, UK.

7.

W. Lubeigt, G. Valentine, J. Girkin, E. Bente, and D. Burns, “Active transverse mode control and optimization of an all-solid-state laser using an intracavity adaptive-optic mirror,” Opt. Express 10(13), 550–555 (2002).

8.

W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]

9.

B. V. Flexible Optical, PO Box 581, 2600 AN, Delft, the Netherlands, www.okotech.com

10.

W. Koechner, Solid-State Laser Engineering, 5th edition (Springer Series in Optical Sciences, New-York, 1999)

11.

Cutting Edge Optronics, Cutting Edge Optronics, 20 Point West Boulevard, St. Charles, MO 63301, USA, http://www.st.northropgrumman.com/ceolaser/.

12.

L. A. S. C. A. D. Gmbh, Brimhildenstr. 9, 80639 Munich, Germany, http://www.las-cad.com/index.php.

13.

COMSOL Multiphysics, COMSOL Inc., 1 New England Executive Park, Suite 350, Burlington, MA 01803, USA.

14.

Winlase II, Future Laser Technologies, 5051 Alton Pkwy #102, Irvine, CA 92604, USA.

15.

MICOS VT-80, MICOS GmbH, Freiburger Str. 30, DE-79427 Eschbach, Germany.

OCIS Codes
(010.1080) Atmospheric and oceanic optics : Active or adaptive optics
(140.3580) Lasers and laser optics : Lasers, solid-state
(140.6810) Lasers and laser optics : Thermal effects

ToC Category:
Lasers and Laser Optics

History
Original Manuscript: March 24, 2009
Revised Manuscript: June 5, 2009
Manuscript Accepted: June 7, 2009
Published: July 2, 2009

Citation
Walter Lubeigt, Mike Griffith, Leslie Laycock, and David Burns, "Reduction of the time-to-full-brightness in solid-state lasers using intra-cavity adaptive optics," Opt. Express 17, 12057-12069 (2009)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-14-12057


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References

  1. I. Moshe, S. Jackel, and R. Lallouz, “Working beyond the static limits of laser stability by use of adaptive and polarization-conjugation optics,” Appl. Opt. 37(27), 6415–6420 (1998). [CrossRef]
  2. J. W. Hardy, Adaptive Optics for Astronomical Telescope (Oxford University Press US, 1998), Chap. 6.6.
  3. A. V. Ikramov, I. M. Roshchupkin, and A. G. Safronov, “Cooled bimorph adaptive mirrors for laser optics,” Quantum Electron. 24(7), 613–617 (1994). [CrossRef]
  4. J. C. Dainty, A. V. Koryabin, and A. V. Kudryashov, “Low-order adaptive deformable mirror,” Appl. Opt. 37(21), 4663–4668 (1998). [CrossRef]
  5. T. Y. Cherezova, L. N. Kaptsov, and A. V. Kudryashov, “Cw industrial rod YAG:Nd3+ laser with an intracavity active bimorph mirror,” Appl. Opt. 35(15), 2554–2561 (1996). [CrossRef]
  6. BAE Systems Advanced Technology Centre, West Hanningfield rd, Great Baddow, Chelmsford CM2 8HN, UK.
  7. W. Lubeigt, G. Valentine, J. Girkin, E. Bente, and D. Burns, “Active transverse mode control and optimization of an all-solid-state laser using an intracavity adaptive-optic mirror,” Opt. Express 10(13), 550–555 (2002).
  8. W. Lubeigt, G. Valentine, and D. Burns, “Enhancement of laser performance using an intracavity deformable membrane mirror,” Opt. Express 16(15), 10943–10955 (2008). [CrossRef]
  9. B. V. Flexible Optical, PO Box 581, 2600 AN, Delft, the Netherlands, www.okotech.com
  10. W. Koechner, Solid-State Laser Engineering, 5th edition (Springer Series in Optical Sciences, New-York, 1999)
  11. Cutting Edge Optronics, Cutting Edge Optronics, 20 Point West Boulevard, St. Charles, MO 63301, USA, http://www.st.northropgrumman.com/ceolaser/ .
  12. L. A. S. C. A. D. Gmbh, Brimhildenstr. 9, 80639 Munich, Germany, http://www.las-cad.com/index.php .
  13. COMSOL Multiphysics, COMSOL Inc., 1 New England Executive Park, Suite 350, Burlington, MA 01803, USA.
  14. Winlase II, Future Laser Technologies, 5051 Alton Pkwy #102, Irvine, CA 92604, USA.
  15. MICOS VT-80, MICOS GmbH, Freiburger Str. 30, DE-79427 Eschbach, Germany.

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