The present invention provides a two-photon light-emitting compound represented by formula (1), an optical data recording medium comprising a compound represented by formula (1), a two-photon polymerizable composition comprising a polymerizable monomer or polymerizable oligomer and at least a compound represented by formula (1), and a photopolymerization process: <?in-line-formulae description='In-line Formulae' end='lead'?>X<SUP>2</SUP>-(-CR<SUP>4</SUP>-CR<SUP>3</SUP>-)<SUB>m</SUB>-C(-O)-(-CR<SUP>1</SUP>-CR<SUP>2</SUP>-)<SUB>n</SUB>-X<SUP>1 </SUP> ( 1 ) <?in-line-formulae description='In-line Formulae' end='tail'?> wherein X<SUP>1 </SUP>and X<SUP>2 </SUP>may be the same or different and each represent a substituted or unsubstituted aryl group or a substituted or unsubstituted heterocyclic group; R<SUP>1</SUP>, R<SUP>2</SUP>, R<SUP>3 </SUP>and R<SUP>4 </SUP>each independently represent a hydrogen atom or substituent; some of R<SUP>1</SUP>, R<SUP>2</SUP>, R<SUP>3 </SUP>and R<SUP>4 </SUP>may be connected to each other to form at least one ring; and n and m each independently represent an integer of from 1 to 4, with the proviso that when n and m are 2 or more, the plurality of R<SUP>1</SUP>'s, R<SUP>2</SUP>'s, R<SUP>3</SUP>'s, and R<SUP>4</SUP>'s each may be the same or different.
Non-resonant two-photon absorption induction method and process for emitting light thereby, optical data recording medium and process for recording data thereon