Abstract

Laser brightness is a measure of the ability to deliver intense light to a target and encapsulates both the energy content and the beam quality. High-brightness lasers require that both parameters be maximized, yet standard laser cavities do not allow this. For example, multimode beams, a mix of many transverse modes, have a high energy content but low beam quality, while single transverse mode Gaussian beams have a good beam quality, but their small mode volume means a low energy extraction. Here we overcome this fundamental limitation and demonstrate an optimal approach to realizing high-brightness lasers. We employ intra-cavity beam shaping to produce a single transverse mode that changes profile inside the cavity, Gaussian at the output end and flattop at the gain end, such that both energy extraction and beam quality are simultaneously optimized. This work should have a significant influence on the design of future high-brightness laser cavities.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Full Article  |  PDF Article
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References

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2017 (1)

I. A. Litvin, G. King, and H. Strauss, “Beam shaping laser with controllable gain,” Appl. Phys. B 123, 174 (2017).
[Crossref]

2016 (1)

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

2015 (2)

2014 (1)

2013 (1)

2012 (2)

2011 (2)

2009 (3)

2008 (1)

2007 (2)

2006 (1)

M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd:YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
[Crossref]

2005 (2)

M. Kuznetsov, M. Stern, and J. Copetta, “Single transverse mode optical resonators,” Opt. Express 13, 171–181 (2005).
[Crossref]

T. Y. Fan, “Laser beam combining for high-power, high-radiance sources,” IEEE J. Sel. Top. Quantum Electron. 11, 567–577 (2005).
[Crossref]

2004 (1)

M. Gerber and T. Graf, “Generation of super-Gaussian modes in Nd:YAG lasers with a graded-phase mirror,” IEEE J. Quantum Electron. 40, 741–746 (2004).
[Crossref]

2002 (1)

2001 (1)

2000 (2)

A. E. Siegman, “Laser beams and resonators: the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1380–1388 (2000).
[Crossref]

A. E. Siegman, “Laser beams and resonators: beyond the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1389–1399 (2000).
[Crossref]

1998 (1)

T. Y. Cherezova, S. S. Chesnokov, L. N. Kaptsov, and A. V. Kudryashov, “Super-Gaussian laser intensity output formation by means of adaptive optics,” Opt. Commun. 155, 99–106 (1998).
[Crossref]

1996 (2)

1994 (2)

1992 (3)

P. A. Bélanger, R. L. Lachance, and C. Paré, “Super-Gaussian output from a CO2 laser by using a graded-phase mirror resonator,” Opt. Lett. 17, 739–741 (1992).
[Crossref]

C. Paré, L. Gagnon, and P. A. Bélanger, “Aspherical laser resonators: an analogy with quantum mechanics,” Phys. Rev. A 46, 4150–4160 (1992).
[Crossref]

C. Paré and P. A. Bélanger, “Custom laser resonators using graded-phase mirrors,” IEEE J. Quantum Electron. 28, 355–362 (1992).
[Crossref]

1991 (1)

1990 (1)

A. E. Siegman, “New developments in laser resonators,” Proc. SPIE 1224, 2–14 (1990).
[Crossref]

1988 (1)

T. Y. Fan and R. L. Byer, “Diode laser-pumped solid-state lasers,” IEEE J. Quantum Electron. 24, 895–912 (1988).
[Crossref]

Ait-Ameur, K.

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

S. Ngcobo, K. Ait-Ameur, I. Litvin, A. Hasnaoui, and A. Forbes, “Tuneable Gaussian to flat-top resonator by amplitude beam shaping,” Opt. Express 21, 21113–21118 (2013).
[Crossref]

Augst, S. J.

Barré, N.

Barthélémy, A.

Bélanger, P. A.

C. Paré, L. Gagnon, and P. A. Bélanger, “Aspherical laser resonators: an analogy with quantum mechanics,” Phys. Rev. A 46, 4150–4160 (1992).
[Crossref]

C. Paré and P. A. Bélanger, “Custom laser resonators using graded-phase mirrors,” IEEE J. Quantum Electron. 28, 355–362 (1992).
[Crossref]

P. A. Bélanger, R. L. Lachance, and C. Paré, “Super-Gaussian output from a CO2 laser by using a graded-phase mirror resonator,” Opt. Lett. 17, 739–741 (1992).
[Crossref]

P. A. Bélanger and C. Paré, “Optical resonators using graded-phase mirrors,” Opt. Lett. 16, 1057–1059 (1991).
[Crossref]

Bente, E.

Bouazaoui, M.

Bouwmans, G.

Brunel, M.

Burns, D.

Byer, R. L.

T. Y. Fan and R. L. Byer, “Diode laser-pumped solid-state lasers,” IEEE J. Quantum Electron. 24, 895–912 (1988).
[Crossref]

R. L. Byer, “Diode pumped solid state lasers,” in Conference on Lasers and Electro-Optics/Pacific Rim (Optical Society of America, 2009).

Caley, A. J.

Chann, B.

Chen, D.

Cherezova, T. Y.

Chesnokov, S. S.

T. Y. Cherezova, S. S. Chesnokov, L. N. Kaptsov, V. V. Samarkin, and A. V. Kudryashov, “Active laser resonator performance: formation of a specified intensity output,” Appl. Opt. 40, 6026–6033 (2001).
[Crossref]

T. Y. Cherezova, S. S. Chesnokov, L. N. Kaptsov, and A. V. Kudryashov, “Super-Gaussian laser intensity output formation by means of adaptive optics,” Opt. Commun. 155, 99–106 (1998).
[Crossref]

Connors, M. K.

Copetta, J.

Creedon, K.

Creedon, K. J.

Dai, K.

Delplace, K.

Desfarges-Berthelemot, A.

Dickey, F. M.

Druon, F.

El Hamzaoui, H.

Fan, T. Y.

Fischer, R.

Forbes, A.

Fromager, M.

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

Gagnon, L.

C. Paré, L. Gagnon, and P. A. Bélanger, “Aspherical laser resonators: an analogy with quantum mechanics,” Phys. Rev. A 46, 4150–4160 (1992).
[Crossref]

Georges, P.

Gerber, M.

M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd:YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
[Crossref]

M. Gerber and T. Graf, “Generation of super-Gaussian modes in Nd:YAG lasers with a graded-phase mirror,” IEEE J. Quantum Electron. 40, 741–746 (2004).
[Crossref]

Girkin, J.

Goldizen, K. C.

Goodno, G.

H. Injeyan and G. Goodno, High Power Laser Handbook (McGraw-Hill, 2011), Chap. 19.

Graf, T.

M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd:YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
[Crossref]

M. Gerber and T. Graf, “Generation of super-Gaussian modes in Nd:YAG lasers with a graded-phase mirror,” IEEE J. Quantum Electron. 40, 741–746 (2004).
[Crossref]

Griffith, M.

Guichard, F.

Hafizi, B.

Hanna, M.

Harfouche, A.

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

Hasnaoui, A.

Hodgson, N.

N. Hodgson and H. Weber, Laser Resonators and Beam Propagation (Springer, 2005), p. 476.

Huang, R. K.

Injeyan, H.

H. Injeyan and G. Goodno, High Power Laser Handbook (McGraw-Hill, 2011), Chap. 19.

Kansky, J.

Kansky, J. E.

Kaptsov, L. N.

Kermène, V.

King, G.

I. A. Litvin, G. King, and H. Strauss, “Beam shaping laser with controllable gain,” Appl. Phys. B 123, 174 (2017).
[Crossref]

Koechner, W.

W. Koechner, Solid-State Laser Engineering (Springer, 2006), p. 193.

Kudryashov, A.

M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd:YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
[Crossref]

Kudryashov, A. V.

Kuznetsov, M.

Labat, D.

Lachance, R. L.

Laycock, L.

Leger, J.

Leger, J. R.

Litvin, I.

Litvin, I. A.

Liu, J.

Lombard, L.

Lubeigt, W.

Missaggia, L. J.

Montoya, J.

Murphy, D. V.

Naidoo, D.

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

Ngcobo, S.

Oak, S.

Paré, C.

C. Paré, L. Gagnon, and P. A. Bélanger, “Aspherical laser resonators: an analogy with quantum mechanics,” Phys. Rev. A 46, 4150–4160 (1992).
[Crossref]

C. Paré and P. A. Bélanger, “Custom laser resonators using graded-phase mirrors,” IEEE J. Quantum Electron. 28, 355–362 (1992).
[Crossref]

P. A. Bélanger, R. L. Lachance, and C. Paré, “Super-Gaussian output from a CO2 laser by using a graded-phase mirror resonator,” Opt. Lett. 17, 739–741 (1992).
[Crossref]

P. A. Bélanger and C. Paré, “Optical resonators using graded-phase mirrors,” Opt. Lett. 16, 1057–1059 (1991).
[Crossref]

Pouysegur, J.

Prévost, F.

Ramirez, L. P.

Ranganathan, K.

Redmond, S. M.

Rigaud, P.

Romanelli, M.

Romero, L. A.

Samarkin, V. V.

Sanchez, A.

Sanchez-Rubio, A.

Siegman, A.

A. Siegman, Lasers (University Science Books, 1986), p. 706.

Siegman, A. E.

A. E. Siegman, “Laser beams and resonators: the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1380–1388 (2000).
[Crossref]

A. E. Siegman, “Laser beams and resonators: beyond the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1389–1399 (2000).
[Crossref]

A. E. Siegman, “New developments in laser resonators,” Proc. SPIE 1224, 2–14 (1990).
[Crossref]

Smith, G. M.

Sprangle, P.

Stern, M.

Strauss, H.

I. A. Litvin, G. King, and H. Strauss, “Beam shaping laser with controllable gain,” Appl. Phys. B 123, 174 (2017).
[Crossref]

Sundar, R.

Taghizadeh, M. R.

Thomson, M. J.

Tiffany, B.

Ting, A.

Turner, G. W.

Valentine, G.

Waddie, A. J.

Wang, Z.

Weber, H.

N. Hodgson and H. Weber, Laser Resonators and Beam Propagation (Springer, 2005), p. 476.

Yu, C. X.

Zaouter, Y.

Appl. Opt. (5)

Appl. Phys. B (2)

M. Gerber, T. Graf, and A. Kudryashov, “Generation of custom modes in a Nd:YAG laser with a semipassive bimorph adaptive mirror,” Appl. Phys. B 83, 43–50 (2006).
[Crossref]

I. A. Litvin, G. King, and H. Strauss, “Beam shaping laser with controllable gain,” Appl. Phys. B 123, 174 (2017).
[Crossref]

IEEE J. Quantum Electron. (3)

T. Y. Fan and R. L. Byer, “Diode laser-pumped solid-state lasers,” IEEE J. Quantum Electron. 24, 895–912 (1988).
[Crossref]

C. Paré and P. A. Bélanger, “Custom laser resonators using graded-phase mirrors,” IEEE J. Quantum Electron. 28, 355–362 (1992).
[Crossref]

M. Gerber and T. Graf, “Generation of super-Gaussian modes in Nd:YAG lasers with a graded-phase mirror,” IEEE J. Quantum Electron. 40, 741–746 (2004).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (3)

T. Y. Fan, “Laser beam combining for high-power, high-radiance sources,” IEEE J. Sel. Top. Quantum Electron. 11, 567–577 (2005).
[Crossref]

A. E. Siegman, “Laser beams and resonators: the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1380–1388 (2000).
[Crossref]

A. E. Siegman, “Laser beams and resonators: beyond the 1960s,” IEEE J. Sel. Top. Quantum Electron. 6, 1389–1399 (2000).
[Crossref]

J. Luminesc. (1)

D. Naidoo, A. Harfouche, M. Fromager, K. Ait-Ameur, and A. Forbes, “Emission of a propagation invariant flat-top beam from a microchip laser,” J. Luminesc. 170, 750–754 (2016).
[Crossref]

J. Opt. Soc. Am. A (1)

Opt. Commun. (1)

T. Y. Cherezova, S. S. Chesnokov, L. N. Kaptsov, and A. V. Kudryashov, “Super-Gaussian laser intensity output formation by means of adaptive optics,” Opt. Commun. 155, 99–106 (1998).
[Crossref]

Opt. Express (8)

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, 550–555 (2002).
[Crossref]

W. Lubeigt, M. Griffith, L. Laycock, and D. Burns, “Reduction of the time-to-full-brightness in solid-state lasers using intra-cavity adaptive optics,” Opt. Express 17, 12057–12069 (2009).
[Crossref]

A. J. Caley, M. J. Thomson, J. Liu, A. J. Waddie, and M. R. Taghizadeh, “Diffractive optical elements for high gain lasers with arbitrary output beam profiles,” Opt. Express 15, 10699–10704 (2007).
[Crossref]

I. A. Litvin and A. Forbes, “Intra-cavity flat-top beam generation,” Opt. Express 17, 15891–15903 (2009).
[Crossref]

L. P. Ramirez, M. Hanna, G. Bouwmans, H. El Hamzaoui, M. Bouazaoui, D. Labat, K. Delplace, J. Pouysegur, F. Guichard, P. Rigaud, V. Kermène, A. Desfarges-Berthelemot, A. Barthélémy, F. Prévost, L. Lombard, Y. Zaouter, F. Druon, and P. Georges, “Coherent beam combining with an ultrafast multicore Yb-doped fiber amplifier,” Opt. Express 23, 5406–5416 (2015).
[Crossref]

S. Ngcobo, K. Ait-Ameur, I. Litvin, A. Hasnaoui, and A. Forbes, “Tuneable Gaussian to flat-top resonator by amplitude beam shaping,” Opt. Express 21, 21113–21118 (2013).
[Crossref]

M. Kuznetsov, M. Stern, and J. Copetta, “Single transverse mode optical resonators,” Opt. Express 13, 171–181 (2005).
[Crossref]

B. Tiffany and J. Leger, “Losses of bound and unbound custom resonator modes,” Opt. Express 15, 13463–13475 (2007).
[Crossref]

Opt. Lett. (9)

J. R. Leger, D. Chen, and Z. Wang, “Diffractive optical element for mode shaping of a Nd:YAG laser,” Opt. Lett. 19, 108–110 (1994).
[Crossref]

P. A. Bélanger, R. L. Lachance, and C. Paré, “Super-Gaussian output from a CO2 laser by using a graded-phase mirror resonator,” Opt. Lett. 17, 739–741 (1992).
[Crossref]

P. A. Bélanger and C. Paré, “Optical resonators using graded-phase mirrors,” Opt. Lett. 16, 1057–1059 (1991).
[Crossref]

C. X. Yu, S. J. Augst, S. M. Redmond, K. C. Goldizen, D. V. Murphy, A. Sanchez, and T. Y. Fan, “Coherent combining of a 4  kW, eight-element fiber amplifier array,” Opt. Lett. 36, 2686–2688 (2011).
[Crossref]

K. J. Creedon, S. M. Redmond, G. M. Smith, L. J. Missaggia, M. K. Connors, J. E. Kansky, T. Y. Fan, G. W. Turner, and A. Sanchez-Rubio, “High efficiency coherent beam combining of semiconductor optical amplifiers,” Opt. Lett. 37, 5006–5008 (2012).
[Crossref]

S. M. Redmond, K. J. Creedon, J. E. Kansky, S. J. Augst, L. J. Missaggia, M. K. Connors, R. K. Huang, B. Chann, T. Y. Fan, G. W. Turner, and A. Sanchez-Rubio, “Active coherent beam combining of diode lasers,” Opt. Lett. 36, 999–1001 (2011).
[Crossref]

I. A. Litvin and A. Forbes, “Gaussian mode selection with intracavity diffractive optics,” Opt. Lett. 34, 2991–2993 (2009).
[Crossref]

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Figures (8)

Fig. 1.
Fig. 1. Schematic showing the metamorphosis of a Gaussian beam into an FTB with two phase-only optical elements. The first optical element, ψ1(ρ), is used to transform a Gaussian field into a flattop. The second element, ψ2(r), is encoded as the conjugate of the field at that plane such that the output FTB has a flat wavefront. Both elements have a phase variation of 02π (white to black) and are depicted as gray-scale images.
Fig. 2.
Fig. 2. We performed a matrix-style Fox–Li simulation of the cavity without gain and illustrate that the lowest loss mode is a structure that morphs from a (a) Gaussian profile at the OC to a (b) flattop at the HR. The next two competing modes at the (c) and (e) OC likewise morph in profile to the (d) and (f) HR but are far from the desired profiles. The resulting losses associated with the mode [(a), (c), (e) eigenvalues shown in blue] imply poor mode discrimination based on diffraction losses. The required discrimination is provided by gain-to-mode overlap with (b) 91% for the desired flattop, (d) 23% for TEM10 and (f) 17% for TEM20. (g) Ray-tracing calculation showing that the ray trajectories are parallel at each mirror.
Fig. 3.
Fig. 3. Modal discrimination of higher unwanted modes is determined primarily by the pump-to-mode overlap and not by the modal diffraction losses. Here we show the fluorescence of the side-pumped gain medium used in our experiment, which closely approximates as flattop. The overlaps between this gain and the first two lowest loss modes in the cavity, TEM00 and TEM10, respectively, are given by η00=91% and η10=23%.
Fig. 4.
Fig. 4. (a) Single intra-cavity round trip may be represented as an unfolded cavity with two phase transformations. (b) The external optical testing of a single round trip was executed experimentally using a SLM using a split-screen functionality. The left half of the screen was addressed with a phase profile of the first element (ψ1(ρ)), while the right half of the screen was addressed with a phase profile of double the second element (2ψ2(r)). A collimated Gaussian beam was propagated to the left half of the screen, and the resulting flattop intensity profile was measured on CCD1. With a PFM acting in a reflective capacity, the FTB was directed to the right half of the SLM screen, and the resulting beam was measured on CCD2 after reflection off a FM.
Fig. 5.
Fig. 5. External optical testing of a single round trip was executed by propagating a collimated (a) Gaussian beam of w0=1  mm onto an appropriate phase pattern for transformation to an FTB of width wFTB=1.8  mm. The output resulted in a well-defined (b) FTB of edge-to-edge diameter of 3.61 mm (measured wFTB=1.81  mm). The FTB was directed onto the second element and was transformed to a (c) Gaussian beam (measured w0=0.95  mm). The profiles below the 2D beam images demonstrate high overlap between the expected intensities and the experimentally measured intensities.
Fig. 6.
Fig. 6. (a) Laser cavity with the inclusion of the beam transformation elements was compared to an empty cavity. Near-field outputs from the two cavities show (b) multimode operation for the empty cavity and (c) Gaussian-like operation for the custom cavity. The profiles in the Fourier plane of the OC likewise confirm this property, with the empty cavity shown in (d) and the custom cavity in (e). (f) Experimental and theoretical profiles of the output mode from the designed cavity.
Fig. 7.
Fig. 7. Optics were manufactured using gray-scale lithography with an AZ4562 Photoresist. The manufacturer characterized the components where (a) the target height profile corresponds to our design. (b) The measured height profile using a Zygo interferometer illustrates a maximum height of 1889 nm and is scaled by a factor of about 1.3 due to the etching process and arrives at 2370 nm. This corresponds to an excellent agreement with the target profile. (c) The surface deviation is computed between the target profile and the measured profile. Here the RMS height deviation is minimal and is calculated to be 20 nm. (d) The phase change of the element is calculated and compares exceedingly well to that measured by (e) white-light interferometry. (f) The performance of the measured profile is simulated by modulating a Gaussian beam with this phase. The resulting beam intensity is a uniform flattop.
Fig. 8.
Fig. 8. (a) Measured brightness enhancement for the designed cavity with the optics as compared to the open cavity. The slope difference equates to an approximate enhancement factor of 350%. (b) Measured energy extraction enhancement for the designed cavity with the optics as compared to a cavity apertured to the same size. The slope difference equates to an approximate enhancement factor of 55%.

Equations (9)

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B=PAΩ=P(M2)2λ2,
uG(ρ)=exp[(ρw0)2],
uFTB(ρ)={1for  |ρ|<wFTB0for  |ρ|>wFTB,
ψ1(ρ)=ψF(ρ)kρ22f,
ψF(ρ)=απ20ρ/w01exp(ξ2)dξ,
α=2πw0wFTBfλ.
ψ2(r)=arg{exp[i(kr22f+ψF(ϑ(r))αrϑ(r)w0wFTB)]},
η=TEMnm|MpTEMnm|TEMnmMp|Mp,
η=BnewB0=ε(M02Mnew2)2,