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Durham University

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Staff Profile

Dr Graham Cross, BSc., PhD., CPhys. MInst.Phys.

Senior Lecturer in the Department of Physics
Telephone: +44 (0) 191 33 43577
Room number: Ph323
Room number: 105

(email at


Teaching activity

Level 2 Laboratory Leader, L3 Team Projects

Research interests

I have a well established research history in the fields of light/matter interactions and development of optical waveguide photonic devices. Previous contributions have been to the area of nonlinear optical interactions in organic materials with the aim of finding materials and device solutions that would allow commercial application of polymers to photonics technologies.

My introduction of the biophysical characterisation method Dual Polarisation Interferometry (DPI) and its successful commercialisation is a highlight of my career to date.

The tool itself is now my focus of research into microscopic (linear) light/matter interactions. The current focus is on answering fundamental questions on the applicability of continuum models for the constitutive optical properties of matter when the evanescent light supplied by the DPI waveguide interacts with a highly dilute matter field.

Certain properties of materials such as the refractive index (or electrical conductivity) require energy transport models where the medium must be considered homogeneous on the relevant wavelength scales. But one could question the validity of effective medium models when permittivity discontinuities (e.g. 'refractive contrast' inclusions) are spaced beyond these scales. How can a conventional refractive index then be applied to explain the transport properties? In fact, to successfully use the concept of refractive index one has to assume that the incident electromagnetic field extends sufficiently across space to generate a notionally 'valid' statistical average of induced currents from all irradiated parts of the material. If this is not the case the refractive index loses its usual meaning and becomes irrelevant to the description of energy transport. One example of this reveals a fundamental limit to the use of continuum models of electromagnetism.

The DPI technique has the sensitivity and unique ability to record the quantitative and qualitative details of the phase paths taken by light propagating through such dilute discontinuous media. The experiments record data continuously during matter field (deposited layer) formation from dilute though to dense media and the complete phase path record reveals the matter field density point at which conventional homogeneous media assumptions can be safely applied. The technique has been dubbed a "Matter Field Microscope" where increasing the spatial frequency of the refractive discontinuities is akin to increasing the resolving power of a microscope. Light itself is the object of illumination in this inverted concept of microscopy.


Research Groups

Centre for Materials Physics

  • Photonic Sensors and Materials

Department of Physics

Research Interests

  • Nonlinear optical materials
  • Optical waveguide devices
  • Optoelectronics


  • 1: Cross, Graham Hugh (2013). Fundamental limit to the use of effective medium theories in optics. Optics Letters 38(16): 3057-3060.
  • 2: Cross, G.H. (2013). Light under a matter field microscope. arXiv 1303:1390.
  • 3: Cross, G. H. & Brand, S (2011). Wavelength-dependent frustrated internal reflection via photonic interface states. Applied Physics Letters 99(19): 191106
  • 4: Tan, Osbert, Clark, S.J., Szablewski, M. & Cross, G.H. (2010). Understanding the optical spectroscopy of amphiphilic molecular rectifiers: A density functional approach. Journal of Chemical Physics 133(24): 244702.
  • 5: Tan, Osbert & Cross, Graham H (2009). Surface anchoring structure of a liquid crystal monolayer studied via dual polarisation interferometry. Physical Review E 79(2): 021703.
  • 6: Campo, J, Wenseleers, W, Goovaerts, E, Szablewski, M & Cross, GH (2008). Accurate determination and modeling of the dispersion of the first hyperpolarizability of an efficient zwitterionic nonlinear optical chromophore by tunable wavelength hyper-Rayleigh scattering. Journal Of Physical Chemistry C 112(1): 287-296.
  • Graham H. Cross, Neville J. Freeman & Marcus J. Swann (2007). Dual Polarization Interferometry: A Real-Time Optical Technique for Measuring (Bio)molecular Orientation, Structure and Function at the Solid/Liquid Interface. In Handbook of Biosensors and Biochips. Robert S. Marks, David C. Cullen, Isao Karube, Christopher R. Lowe & Howard H. Weetall Chichester, England: John Wiley.
  • Benoist, Caroline C. & Cross, Graham H. (2018). A photographic methodology for analysing bit position under rein tension. Journal of Equine Veterinary Science 67: 102-111.
  • Cross, G.H. & Cassidy, D.J. (2007). Universal method to determine the thermo-optic coefficient of optical waveguide layer materials using a dual slab waveguide. Applied Physics Letters 91(14): 141914.
  • Palsson, L.O., Vaughan, H.L., Smith, A., Szablewski, M., Cross, G.H., Roberts, T., Masutani, A., Yasuda, A., Beeby, A. & Bloor, D. (2006). Guest-host interactions between dichroic dyes and anisotropic hosts. Journal of luminescence 117(1): 113-122.
  • Freeman NJ, Peel LL, Swann MJ, Cross GH, Reeves A, Brand S & Lu JR (2004). Real Time, High Resolution Studies Of Protein Adsorption And Structure At The Solid-liquid Interface Using Dual Polarization Interferometry. Journal of Physics: Condensed Matter 16: S2493-S2496.
  • Cross G. H., Reeves A., Brand S., Swann M. J., Peel L. L., Freeman N. J. & Lu J. R. (2004). The metrics of surface adsorbed small molecules on the Young's fringe dual-slab waveguide interferometer. Journal of Physics D: Applied Physics 37(1): 74-80.
  • Cross G. H., Reeves A. A., Brand S., Popplewell J. F., Peel L. L., Swann M. J. & Freeman N. J. (2003). A new quantitative optical biosensor for protein characterisation. Biosensors & Bioelectronics 19(4): 383-390.
  • Cross, G. H., Hackman, N. A., Thomas, P. R., Szablewski, M., Pålsson, L.-O. & Bloor, D. (2003). Local field and aggregation dependence of the micro- and macroscopic optical non-linearity of zwitterionic molecules. Optical Materials 21(1-3): 29-37.
  • Palsson, L-O., Szablewski, M., Roberts, A., Masutani, A., Love, G. D., Cross, G. H., Bloor, D., Kay, A. J., Woolhouse, A. D., Masutani, A. & Yasuda, A. (2003). Orientation and solvatochromism of dyes in liquid crystals. Molecular Crystals and Liquid Crystals 402(1): 279-289.
  • Cole, J. M., Copley, R. C. B., McIntyre, G. J., Howard, J. A. K., Szablewski, M. & Cross, G. H. (2002). Charge-density study of the nonlinear optical precursor DED-TCNQ at 20 K. Physical Review B 65(12): 125107.
  • Cross G. H. & Strachan E. E. (2002). Diode laser wavelength tracking using an integrated dual slab waveguide interferometer. IEEE Photonics Technology Letters 14(7): 950-952.
  • Palsson, L.O., Wang, C.S., Russell, D.L., Monkman, A.P., Bryce, M.R., Rumbles, G. & Samuel, I.D.W. (2002). Photophysics of a fluorene co-polymer in solution and films. Chemical physics 279(2-3): 229-237.
  • Ren YT & Cross GH (2002). Photostability Studies On High Dipole Nonlinear Optical Adducts Of Tcnq In Polymer Optical Waveguides. Journal Of Nonlinear Optical Physics & Materials 11: 131-142.
  • Bloor, D., Kagawa, Y., Szablewski, M., Ravi, M., Clark, S. J., Cross, G. H., Palsson, L-O., Beeby, A., Parmer, C. & Rumbles, G. (2001). Matrix dependence of light emission from TCNQ adducts. Journal of Materials Chemistry 11(12): 3053-3062.
  • Ren YT, Mormile P, Petti L & Cross GH (2001). Optical Waveguide Humidity Sensor With Symmetric Multilayer Configuration. Sensors And Actuators B-chemical 75: 76-82.
  • Cross GH & Ren YT (2001). Optical Waveguide Humidity Sensor With Symmetric Multilayer Configuration (vol 75, Pg 76, 2001). Sensors And Actuators B-chemical 79: 216-216.
  • Kagawa, Y, Takada, N, Matsuda, H, Yase, K, Halim, M, Samuel, IW, Cross, GH & Bloor, D (2000). Photo- and electroluminescence for TCNQ-amino adducts. Molecular Crystals And Liquid Crystals 349: 499-502.
  • Cross, G.H., Ren, Y.T. & Swann, M.J. (2000). Refractometric discrimination of void-space filling and swellingduring vapour sorption in polymer films. Analyst 125(12): 2173-2175.
  • Zaidi NA, Bryce MR & Cross GH (2000). Synthesis And Optical Properties Of New Tricyano-p-quinodimethane Dyes: Molecular And Polymeric Systems. Tetrahedron Letters 41: 4645-4649.
  • Ren YT, Szablewski M & Cross GH (2000). Waveguide Photodegradation Of Nonlinear Optical Organic Chromophores In Polymeric Films. Applied Optics 39: 2499-2506.
  • Ravi M, Szablewski M, Hackman NA, Cross GH, Bloor D, Goeta AE & Howard JAK (1999). Crystal Structures Of Amino Substituted Dicyanoquinodimethanes With Potential Nonlinear Optical Applications. New Journal Of Chemistry 23: 841-844.
  • Cross, G.H., Ren, Y.T. & Freeman, N.J. (1999). Young’s fringes from vertically integrated slab waveguides: Applications to humidity sensing. Journal Of Applied Physics 86(11): 6483-6488.
  • Szablewski M, Thomas PR, Thornton A, Bloor D, Cross GH, Cole JM, Howard JAK, Malagoli M, Meyers F, Bredas JL, Wenseleers W & Goovaerts E (1997). Highly Dipolar, Optically Nonlinear Adducts Of Tetracyano-p- Quinodimethane: Synthesis, Physical Characterization, And Theoretical Aspects. Journal Of The American Chemical Society 119: 3144-3154.
  • Cross GH, Healy D, Szablewski M, Bloor D, Malagoli M, Kogej T, Beljonne D & Bredas JL (1997). Highly Polar Chromophores In Poled Polymer Films Characterised By Second Harmonic Generation. Chemical Physics Letters 268: 36-42.
  • Thornton, A., Bloor, D., Cross, G.H. & Szablewski, M. (1997). Novel Functionalized Poly(amido Amine) (pamam) Dendrimers: Synthesis And Physical Properties. Macromolecules 30(24): 7600-7603.
  • Healy, D., Bloor, D., Gray, D. and Cross, G. H. (1997). Stabilized nonlinear optical chromophore alignment in high-<IMG ALIGN="BOTTOM" SRC=" 3727/30/22/004/img1.gif"/> guest - host polycarbonates. Journal of Physics D Applied Physics 30: 3079-3084.
  • Cole JC, Cole JM, Cross GH, Farsari M, Howard JAK & Szablewski M (1997). Structural Studies Of A Series Of Organic Non-linear Optical Materials. Acta Crystallographica Section B-structural Science 53: 812-821.
  • Mckinney JD, Mcquillan FS, Chen HL, Hamor TA, Jones CJ, Slaski M, Cross GH & Harding CJ (1997). The Magnetic And Second-order Nonlinear Optical Properties Of Some Paramagnetic Salts Containing Metallocarbaborane Anions. Journal Of Organometallic Chemistry 547: 253-262.
  • Colbert MCB, Lewis J, Long NJ, Raithby PR, Bloor DA & Cross GH (1997). The Synthesis Of Chiral Ferrocene Ligands And Their Metal Complexes. Journal Of Organometallic Chemistry 531: 183-190.
  • Cole JC, Howard JAK, Cross GH & Szablewski M (1995). (z)-(4-[1-cyano-3-(diethyliminio)-1- Propenyl]phenyl)dicyanomethanide, A Novel Blue Window Zwitterionic Molecule For Nonlinear Optics. Acta Crystallographica Section C-crystal Structure Communications 51: 715-718.
  • Coe BJ, Hamor TA, Jones CJ, McCleverty JA, Bloor D, Cross GH & Axon TL (1995). Nonlinear And Potential Nonlinear-optical Materials Containing Molybdenum Or Tungsten Mononitrosyl Redox Centers - Stilbene Derivatives Containing Ferrocenyl, Methoxy Or Dimethylamino Donor Groups. Journal Of The Chemical Society-dalton Transactions 673-684.
  • Coe BJ, Foulon JD, Hamor TA, Jones CJ, McCleverty JA, Bloor D, Cross GH & Axon TL (1995). Nonlinear-optical Materials Containing Molybdenum Or Tungsten Mononitrosyl Redox Centers - Diaromatic Azo Derivatives (dec, Pg B427, 1994). Journal Of The Chemical Society-dalton Transactions 153-153.
  • Bruce DW, Thornton A, Chaudret B, Saboetienne S, Axon TL & Cross GH (1995). Pentamethylcyclopentadienyl Ruthenium Complexes As Potential Optically Nonlinear Materials. Polyhedron 14: 1765-1770.
  • Cross, Graham (1995). Propeller molecules take off. Nature 374: 307-308.
  • Rangelrojo R, Kar AK, Wherrett BS, Carroll M, Cross GH & Bloor D (1995). Third-order Optical Nonlinearities Of A Polymeric Film Doped With A Novel Zwitterion, Demi-3cnq. Revista Mexicana De Fisica 41: 832-840.
  • Cross GH & Szablewski M (1994). High Dipole Blue Window Chromophore For Frequency-doubling. Abstracts Of Papers Of The American Chemical Society 208: 254-POLY.
  • Coe BJ, Foulon JD, Hamor TA, Jones CJ, McCleverty JA, Bloor D, Cross GH & Axon TL (1994). Nonlinear-optical Materials Containing Molybdenum Or Tungsten Mononitrosyl Redox Centers - Diaromatic Azo Derivatives. Journal Of The Chemical Society-dalton Transactions 3427-3439.
  • Cross GH, Karakus Y & Bloor D (1993). Electrooptics In Thermopoled Polymer-films. Ieee Transactions On Electrical Insulation 28: 136-142.
  • Houlton A, Miller JR, Silver J, Jassim N, Ahmet MJ, Axon TL, Bloor D & Cross GH (1993). Molecular Materials For Nonlinear Optics - 2nd-harmonic Generation And The Crystal And Molecular-structure Of The 4-nitrophenylimine Of Ferrocenecarboxaldehyde. Inorganica Chimica Acta 205: 67-70.
  • Corriu RJP, Douglas WE, Yang ZX, Karakus Y, Cross GH & Bloor D (1993). Preparation Of Diphenylsilylene Polymers Containing Main-chain Acetylene And (hetero)aromatic Groups - Chi(2) Nonlinear-optical And Other Properties. Journal Of Organometallic Chemistry 455: 69-76.
  • Rychkov, A.A., Cross, G.H. & Gonchar, M.G. (1992). A method for discriminating between 'external' and 'internal' processes leading to voltage decay from electrets in humid conditions. Journal of Physics D Applied Physics 25: 522-524.
  • Rychkov, A. A., Cross, G. H. and Gonchar, M. G. (1992). Charge relaxation in structures containing non-polar polymer-metal interfaces. Journal of Physics D Applied Physics 25: 986-991.
  • Cresswell JP, Cross GH, Bloor D, Feast WJ & Petty MC (1992). Electrooptic Modulation In Polymer Langmuir-blodgett-film Wave-guides. Thin Solid Films 210: 216-218.
  • Karakus, Y., Bloor, D. & Cross, G.H. (1992). Enhanced linear electro-optic response and enhanced stability of thermo-poled 'guest-host' polycarbonate thin films. Journal of Physics D Applied Physics 25: 1014-1018.
  • Cross, G.H., Oldroyd, A.R. & Worboys, M.R. (1990). The linear electro-optic response in crystals of 4-nitro-4'-methyl benzylidene aniline (NMBA). Optics Communications 74: 425-429.
  • Girling IR, Jethwa SR, Stewart RT, Earls JD, Cross GH, Cade NA, Kolinsky PV, Jones RJ & Peterson IR (1988). 2nd-order Non-linear Optical Effects In Langmuir-blodgett Films. Thin Solid Films 160: 355-362.
  • Cross GH, Peterson IR, Girling IR, Cade NA, Goodwin MJ, Carr N, Sethi RS, Marsden R, Gray GW, Lacey D, Mcroberts AM, Scrowston RM & Toyne KJ (1988). A Comparison Of 2nd Harmonic-generation And Electro-optic Studies Of Langmuir-blodgett Monolayers Of New Hemicyanine Dyes. Thin Solid Films 156: 39-52.
  • Cade, N. A., Cross, G. H., Lee, R. A., Bajic, S. and & Latham, R. V. (1988). Field-induced electron emission through Langmuir-Blodgett multilayers. Journal of Physics D Applied Physics 21: 148-153.
  • Cross GH, Girling IR, Peterson IR, Cade NA & Earls JD (1987). Optically Nonlinear Langmuir-blodgett-films - Linear Electrooptic Properties Of Monolayers. Journal Of The Optical Society Of America B-optical Physics 4: 962-967.
  • Cross, G.H., Cade, N.A., Girling, I.R., Peterson, I.R. & Andrews, D.C. (1987). Optically nonlinear Langmuir–Blodgett films: Influence of the substrate on film structure and linear optical properties. Journal Of Chemical Physics 86(2): 1061-1065.
  • Girling, I. R., Cade, N. A., Kolinsky, P. V., Cross, G. & H. and Peterson, I. R. (1986). Surface plasmon enhanced SHG from a hemicyanine monolayer. Journal of Physics D Applied Physics 19: 2065-2075.
  • Ashwell GJ, Cross GH, Sandy IM, Waclawek W & Zabkowska M (1985). Evidence Of Back Charge-transfer In Dmbp-tcnq3. Zeitschrift Fur Naturforschung Section A-a Journal Of Physical Sciences 40: 731-735.
  • Girling IR, Cade NA, Kolinsky PV, Earls JD, Cross GH & Peterson IR (1985). Observation Of 2nd-harmonic Generation From Langmuir-blodgett Multilayers Of A Hemicyanine Dye. Thin Solid Films 132: 101-112.
  • Ashwell GJ, Cross GH, Kennedy DA, Nowell IW & Allen JG (1983). Crystal-structure And Properties Of The 7,7,8,8-tetracyano-para-quinodimethanide Salt Of The 1,1'-bis-(para-cyanophenyl)-4,4'-bipyridinium Dication. Journal Of The Chemical Society-perkin Transactions 2 1787-1791.
  • Ashwell GJ, Allen JG, Cross GH & Nowell IW (1983). Electrical, Magnetic, And Structural Characterization Of The 1-2 And 1-3 Tcnq Salts Of 1,2-bis(4-pyridinium)ethane. Physica Status Solidi A-applied Research 79: 455-463.
  • Ashwell GJ, Allen DW, Cross GH, Kennedy DA & Nowell IW (1982). Crystal-structure Of And Evidence Of A Lattice Distortion In (me2-phi-2p)(tcnq)2. Solid State Communications 43: 731-733.
  • Thomas, P.R. & Cross, G.H. (1997), Problems in the interpretation of solution state NLO measurements of molecular figures of merit [3147-03], Proc. SPIE Vol. 3147, Nonlinear Optical Properties of Organic Materials X. Mark G. Kuzyk, Ed., p.30 3147: 30-.

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