T. P. Devereaux and R. Hackl, “Inelastic light scattering from correlated electrons,” Rev. Mod. Phys. 79, 175–233 (2007).

[CrossRef]

D. M. Newns and C. C. Tsuei, “Fluctuating CuOCu bond model of high-temperature superconductivity,” Nature Phys. 3, 184–191 (2007).

[CrossRef]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

D. S. Chemla and J. Shah, “Many-body and correlation effects in semiconductors,” Nature 411, 549–557 (2001).

[CrossRef]
[PubMed]

A. M. Zheltikov, “Coherent anti-Stokes Raman scattering: from proof-of-the-principle experiments to femtosecond CARS and higher order wave-mixing generalizations,” J. Raman Spectrosc. 31, 653–667 (2000).

[CrossRef]

M. Cardona, “Raman scattering in high T superconductors: phonons, electrons, and electronphonon interaction,” Physica C 317–318, 30–54 (1999).

[CrossRef]

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

B. Fainberg, “Laser-induced grating spectroscopy of electron-phonon interaction in metallic and high-temperature superconductors,” Opt. Commun. 89, 403–409 (1992).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

I. Bozovic, “Plasmons in cuprate superconductors,” Phys. Rev. B 42, 1969–1984 (1990).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

I. Bozovic, “Plasmons in cuprate superconductors,” Phys. Rev. B 42, 1969–1984 (1990).

[CrossRef]

M. Cardona, “Raman scattering in high T superconductors: phonons, electrons, and electronphonon interaction,” Physica C 317–318, 30–54 (1999).

[CrossRef]

D. S. Chemla and J. Shah, “Many-body and correlation effects in semiconductors,” Nature 411, 549–557 (2001).

[CrossRef]
[PubMed]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

T. P. Devereaux and R. Hackl, “Inelastic light scattering from correlated electrons,” Rev. Mod. Phys. 79, 175–233 (2007).

[CrossRef]

B. Fainberg, “Laser-induced grating spectroscopy of electron-phonon interaction in metallic and high-temperature superconductors,” Opt. Commun. 89, 403–409 (1992).

[CrossRef]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

T. P. Devereaux and R. Hackl, “Inelastic light scattering from correlated electrons,” Rev. Mod. Phys. 79, 175–233 (2007).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

C. Thomsen and G. Kaczmarczyk, “Vibrational Raman spectroscopy of high-temperature superconductors,” in Handbook of vibrational spectroscopy, J. M. Chalmers and P. R. Griffiths, eds., pp. 2651 –2669 (John Wiley & Sons, Chichester, 2002).

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

M. D. Levenson, Introduction to Nonlinear Laser Spectroscopy (Academic Press, New York, 1982).

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

S. Mukamel, Principles of Nonlinear Optical Spectroscopy (Oxford University Press, New York, 1995).

D. M. Newns and C. C. Tsuei, “Fluctuating CuOCu bond model of high-temperature superconductivity,” Nature Phys. 3, 184–191 (2007).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

D. S. Chemla and J. Shah, “Many-body and correlation effects in semiconductors,” Nature 411, 549–557 (2001).

[CrossRef]
[PubMed]

Y. R. Shen, The Principles of Nonlinear Optics (John Wiley & Sons, New York, 1984).

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

C. Thomsen and G. Kaczmarczyk, “Vibrational Raman spectroscopy of high-temperature superconductors,” in Handbook of vibrational spectroscopy, J. M. Chalmers and P. R. Griffiths, eds., pp. 2651 –2669 (John Wiley & Sons, Chichester, 2002).

D. M. Newns and C. C. Tsuei, “Fluctuating CuOCu bond model of high-temperature superconductivity,” Nature Phys. 3, 184–191 (2007).

[CrossRef]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

A. M. Zheltikov, “Coherent anti-Stokes Raman scattering: from proof-of-the-principle experiments to femtosecond CARS and higher order wave-mixing generalizations,” J. Raman Spectrosc. 31, 653–667 (2000).

[CrossRef]

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

J. R. Meyer, F. J. Bartoli, E. R. Youngdale, and C. A. Hoffman, “Effects of energy gap and band structure on free-carrier nonlinear susceptibilites in semiconductors,” J. Appl. Phys. 70, 4317–4321 (1991).

[CrossRef]

A. M. Zheltikov, “Coherent anti-Stokes Raman scattering: from proof-of-the-principle experiments to femtosecond CARS and higher order wave-mixing generalizations,” J. Raman Spectrosc. 31, 653–667 (2000).

[CrossRef]

D. S. Chemla and J. Shah, “Many-body and correlation effects in semiconductors,” Nature 411, 549–557 (2001).

[CrossRef]
[PubMed]

M. L. Tacon, A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, and A. Forget, “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of the underdoped cuprates,” Nature Phys. 2, 537–543 (2006).

[CrossRef]

D. M. Newns and C. C. Tsuei, “Fluctuating CuOCu bond model of high-temperature superconductivity,” Nature Phys. 3, 184–191 (2007).

[CrossRef]

B. Fainberg, “Laser-induced grating spectroscopy of electron-phonon interaction in metallic and high-temperature superconductors,” Opt. Commun. 89, 403–409 (1992).

[CrossRef]

V. N. Bagratashvili, V. A. Lobastov, A. N. Zherikhin, V. M. Petnikova, and V. V. Shuvalov, “Nonlinear spectroscopy of Y-Ba-Cu-O and Ni thin films by a biharmonic pumping technique,” Phys. Lett. A 164, 99–102 (1992).

[CrossRef]

A. N. Zherikhin, V. A. Lobastov, V. M. Petnikova, and V. V. Shuvalov, “Biharmonic pumping technique for Y-Ba-Cu-O energy spectrum research in the vicinity of the phase transition,” Phys. Lett. A 179, 145–148 (1993).

[CrossRef]

S. E. Inderhees, M. B. Salamon, T. A. Friedmann, and D. M. Ginsberg, “Measurement of the specific-heat anomaly at the superconducting transition of YBa2Cu3O7-δ,” Phys. Rev. B 36, 2401–2403 (1987).

[CrossRef]

I. Bozovic, “Plasmons in cuprate superconductors,” Phys. Rev. B 42, 1969–1984 (1990).

[CrossRef]

M. Cardona, “Raman scattering in high T superconductors: phonons, electrons, and electronphonon interaction,” Physica C 317–318, 30–54 (1999).

[CrossRef]

T. P. Devereaux and R. Hackl, “Inelastic light scattering from correlated electrons,” Rev. Mod. Phys. 79, 175–233 (2007).

[CrossRef]

N. Gedik, J. Orenstein, R. Liang, D. A. Bonn, and W. N. Hardy, “Diffusion of nonequilibrium quasi-particles in a cuprate superconductor,” Science 300, 1410–1412 (2003).

[CrossRef]
[PubMed]

M. D. Levenson, Introduction to Nonlinear Laser Spectroscopy (Academic Press, New York, 1982).

Y. R. Shen, The Principles of Nonlinear Optics (John Wiley & Sons, New York, 1984).

S. Mukamel, Principles of Nonlinear Optical Spectroscopy (Oxford University Press, New York, 1995).

C. Thomsen and G. Kaczmarczyk, “Vibrational Raman spectroscopy of high-temperature superconductors,” in Handbook of vibrational spectroscopy, J. M. Chalmers and P. R. Griffiths, eds., pp. 2651 –2669 (John Wiley & Sons, Chichester, 2002).

It must be noted that our experimental geometry leads to a small walk-off of the output CRS wave during wavelength tuning, small enough not to lead to significant variations in our detection sensitivity (to minimize this effect, we arranged the detection line so as to have all beam displacements occurring along the long axis of the monochromator entrance slit).