Two-photon or higher-order absorbing optical materials and methods of use

A method for preparing a compound in an electronically excited state, comprising the steps of:

• a) exposing a compound having the formula D1-Π-D2 to pulsed laser radiation, wherein D1 and D2 are electron donor groups;
• and Π comprises a bridge of π-conjugated bonds connecting D1 and D2;
• and
• b) converting said compound to a multi-photon electronically excited state upon simultaneous absorption of at least two photons of said radiation by said compound, wherein the sum of the energies of all of said absorbed photons is greater than or equal to the transition energy from a ground state of said compound to said multi-photon excited state and wherein the energy of each absorbed photon is less than the transition energy between said ground state and the lowest single-photon excited state of said compound and is less than the transition energy between said multi-photon excited state and said ground state.

A method for preparing a compound in an electronically excited state, comprising the steps of:

• a) exposing a compound having the formula A1-Π-A2 to pulsed laser radiation, wherein A1 and A2 are electron acceptors;
• and Π comprises a bridge of π-conjugated bonds connecting A1 and A2;
• and
• b) converting said compound to a multi-photon electronically excited state upon simultaneous absorption of at least two photons of said radiation by said compound, wherein the sum of the energies of all of said absorbed photons is greater than or equal to the transition energy from a ground state of said compound to said multi-photon excited state and wherein the energy of each absorbed photon is less than the transition energy between said ground state and the lowest single-photon excited state of said compound and is less than the transition energy between said multi-photon excited state and said ground state.