Two new polysiloxanes (P1 and P2) with a high density of sulfonyl-based chromophores were prepared by a new two-step method. Poly [methyl-3-(9-carbazolyl) propyl siloxane] was partially formulated by the standard Vilsmeier reaction, and formyl groups of high reactivity were condensed with cyanoacetylated chromophores; this yielded polysiloxanes P1 and P2 in almost complete conversions. Their structures were verified with H-1 NMR, IR, and ultraviolet-visible spectra. P1 and P2 exhibited good solubility in common organic solvents and were thermally stable. The maximum absorptions appeared at about 452 and 390 nm for P1 and P2, respectively, in tetrahydrofuran; they were blueshifted about 42 and 8 nm, respectively, in comparison with those of the corresponding chromophores with a nitro acceptor and resulted in a wider transparency window. The P1 values of the nonlinear optical coefficient (d(33)), measured by in situ second harmonic generation, was 16.2 pm/V. (c) 2005 Wiley Periodicals, Inc.