OLED and OPD-based mini-spectrometer integrated on a single-mode planar waveguide chip M. Ramuz, D. Leuenberger, R. Pfeiffer, L. Bürgi and C. Winnewisser Eur. Phys. J. Appl. Phys., 46 1 (2009) 12510 Published online: 17 March 2009 DOI: 10.1051/epjap/2009025