We have observed nonlinear absorption in spin-coated poly(4,6-decadiyne-1, 10-diolbis {[(n-butoxycarbonyl)methyl]urethane}) [poly(3BCMU)] polydiacetylene channel waveguides at different wavelengths in the near-infrared. Intensity dependent absorption coefficients, α2 and α3, have been determined by measurements of the intensity dependent transmission. The implications of nonlinear absorption for all-optical device applications in this material are discussed.

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We have measured the diffusion and trapping of photoexcited hot carriers in an InGaAs/InP heterostructure using an optical time-of-fight technique with picosecond time resolution. The ambipolar diffusivity is found to decrease by an order of magnitude between 4 K and room temperature, and the efficiency of trapping of carriers into the well increases rapidly in the same temperature range. A mean trapping time of 4 ps is measured for a 50 Å well.

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We report optical absorption and photoluminescence measurements of excitons in Ga0.47In0.53As/InP multiple quantum wells grown by metalorganic chemical vapor deposition. At 4 K the luminescence linewidth for n=1 heavy-hole excitons is measured to be 7 meV for a 30-period structure with wells of width 154 Å. The absorption spectrum at low temperature shows four peaks which we assign to confined heavy-hole excitons. A theoretical calculation of the energies of these states indicates that the ratio of the conduction-band to valence-band energy discontinuities is 45:55.