Radiation pressure and the linear momentum of light in dispersive dielectric media Masud mansuripur Optical Sciences Center, The University of Arona, Tucson, Arisona 85721 Abstract: We derive an exact expression for the radiation pressure of a quasi-monochromatic plane wave incident from the free space onto the flat surface of a semi-infinite dielectric medium In order to account for the total optical momentum (incident plus reflected) that is transferred to the dielectric, the mechanical momentum acquired by the medium must be added to the rate of flow of the electromagnetic momentum( the so-called Abraham momentum) inside the dielectric. We confirm that the lectromagnetic momentum travels with the group velocity of light inside the medium. The photon drag effect in which the photons captured in a emiconductor appear to have the minkowski momentum is explained by analyzing a model system consisting of a thin absorptive layer embedded in I transparent dielectric OCIS codes:(2602110)Electromagnetic theory, (1407010)Trapping. References M. Mansuripur, "Radiation pressure and the linear momentum of the electromagnetic field, "Opt. Express 12 5375-5401(2004),http://www.opticsexpress.org/abstract.cfm?uri=opex-12-22-5375 2. J. P. Gordon, Radiation forces and momenta in dielectric media, "Phys. Rev. A8, 14-21(1973) 3. J.D. Jackson, Classical Electrod namics, 2d edition( Wiley, New York, 1975) 4. R Loudon, "Theory of the radiation pressure on dielectric surfaces, J Mod. Opt. 49, 821-838(2002) 5. Y.N. Obukhov and F. w. Hehl, "Electromagnetic energy-momentum and forces in matter, " Phys. Lett. A 311 277-284(2003) 6. M. Mansuripur, A R. Zakharian, and J. V Moloney, "Radiation pressure on a dielectric wedge, accepted for 7. A.F. Gibson, M. F Kimmitt, and A C. Walker, "Photon drag in Germanium, Appl. Phys. Lett. 17, 75-77 (1970) 8. R Loudon, S M. Barnett, and C. Baxter, "Theory of radiation pressure and momentum transfer in dielectrics: the photon drag effect, "to appear in 2005 1 Introduction In a previous paper [1] we showed that the momentum density p of a plane electro-magnetic wave inside a dispersionless dielectric medium may be expressed as the average of the Minkowski and Abraham momentum densities [2], namely, p=v Real(ExH")c2+ 4 Real(D x B*) Here the complex amplitudes of the electric and magnetic fields within the medium of refractive index n are denoted by E and H, respectively; B=4H, and D= E+P=EEE, where P is the polarization density induced in the medium by the local E-field. E is the permittivity and uo the permeability of free space; E=n is the relative permittivity of the dielectric material [3]. We derived Eq (la) by a direct application of the Lorentz law of force to bound charges and bound currents within the medium- a method that has been the subject of other recent studies as well [4, 5]. It was concluded that the light carries its own electro 6629-$1500US Received 18 February 2005; revised 14 March 2005; accepted 15 March 2005 (C)2005OSA 21 March 2005/ Vol 13. No 6/ OPTICS EXPRESS 2245Radiation pressure and the linear momentum of light in dispersive dielectric media Masud Mansuripur Optical Sciences Center, The University of Arizona, Tucson, Arizona 85721 masud@u.arizona.edu Abstract: We derive an exact expression for the radiation pressure of a quasi- monochromatic plane wave incident from the free space onto the flat surface of a semi-infinite dielectric medium. In order to account for the total optical momentum (incident plus reflected) that is transferred to the dielectric, the mechanical momentum acquired by the medium must be added to the rate of flow of the electromagnetic momentum (the so-called Abraham momentum) inside the dielectric. We confirm that the electromagnetic momentum travels with the group velocity of light inside the medium. The photon drag effect in which the photons captured in a semiconductor appear to have the Minkowski momentum is explained by analyzing a model system consisting of a thin absorptive layer embedded in a transparent dielectric. © 2005 Optical Society of America OCIS codes: (260.2110) Electromagnetic theory; (140.7010) Trapping. References 1. M. Mansuripur, “Radiation pressure and the linear momentum of the electromagnetic field,” Opt. Express 12, 5375-5401 (2004), http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-22-5375. 2. J. P. Gordon, “Radiation forces and momenta in dielectric media,” Phys. Rev. A 8, 14-21 (1973). 3. J. D. Jackson, Classical Electrodynamics, 2nd edition (Wiley, New York, 1975). 4. R. Loudon, “Theory of the radiation pressure on dielectric surfaces,” J. Mod. Opt. 49, 821-838 (2002). 5. Y. N. Obukhov and F. W. Hehl, “Electromagnetic energy-momentum and forces in matter,” Phys. Lett. A 311, 277-284 (2003). 6. M. Mansuripur, A. R. Zakharian, and J. V. Moloney, “Radiation pressure on a dielectric wedge,” accepted for publication, Opt. Express, 2005. 7. A. F. Gibson, M. F. Kimmitt, and A. C. Walker, “Photon drag in Germanium,” Appl. Phys. Lett. 17, 75-77 (1970). 8. R. Loudon, S. M. Barnett, and C. Baxter, “Theory of radiation pressure and momentum transfer in dielectrics: the photon drag effect,” to appear in 2005. 1. Introduction In a previous paper [1] we showed that the momentum density p of a plane electro-magnetic wave inside a dispersionless dielectric medium may be expressed as the average of the Minkowski and Abraham momentum densities [2], namely, p = ¼ Real (E × H*)/c2 + ¼ Real (D × B*). (1a) Here the complex amplitudes of the electric and magnetic fields within the medium of refractive index n are denoted by E and H, respectively; B = µoH, and D = εoE + P = εoε E, where P is the polarization density induced in the medium by the local E-field. εo is the permittivity and µo the permeability of free space; ε = n2 is the relative permittivity of the dielectric material [3]. We derived Eq.(1a) by a direct application of the Lorentz law of force to bound charges and bound currents within the medium – a method that has been the subject of other recent studies as well [4,5]. It was concluded that the light carries its own electro- (C) 2005 OSA 21 March 2005 / Vol. 13, No. 6 / OPTICS EXPRESS 2245 #6629 - $15.00 US Received 18 February 2005; revised 14 March 2005; accepted 15 March 2005