TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The 2-photon absorption compound has a foamable region of formula (11 or 12). The foam material further contains a foamable compound.R21-G-R22 (11)R23-Ntriplebond N X- (12)R21,R22 = H or substituent, and R21 and R22 optionally connect to form a ring or connect with 2-photon absorption compound by covalent bond, ionic bond or coordinate bond;G = -N=N-, -C(O)-, -OC(O)-, -OS(O)-, -S(O)2- or -OS(O)2-;R23 = aryl or heterocyclic ring group;X1 = anion, and X11 or R23 connects with photon absorption component by covalent bond, ionic bond or coordinate bond.Preferably the 2 photon absorption compound is methine pigment or phthalocyanine dye.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Gas: The gas is nitrogen, carbon dioxide, sulfur dioxide, sulfur trioxide, nitrogen dioxide, oxygen or isobutane. The air bubble has size of 50 nm-5 microns and is produced by thermal decomposition. EXAMPLE - Quaternary salt of formula (1) (in g) (14.3) was dissolved in 50 ml of water, sodium hydroxide (1.6) was added and stirred at room temperature for 30 minutes. Reaction mixture was extracted using ethyl acetate and concentrated after drying, and oil (9.2) of methylene base of formula (2) was obtained. Dimethylaminoacrolein (3.97) was dissolved in acetonitrile (50 ml), phosphorous oxychloride (6.75) was dropped at 0degreesC and stirred for 10 minutes. The acetonitrile solution of methylene base was added and stirred at 35degreesC for 4 hours. The reaction solution was poured into 100 ml of ice water, sodium hydroxide (16) was added and refluxed for 10 minutes. The reaction mixture was extracted using ethyl acetate, concentrated and purified by silica gel column chromatography to obtain oil (4.4) of aldehyde of formula (4). Cyclopentanone (0.126) and the aldehyde (0.85) were dissolved in dehydrated methanol and refluxed under nitrogen atmosphere. 28% methanol solution of sodium methoxide was added and refluxed for 6 hours, and cooled. The precipitated crystals were filtered, washed in methanol, and dried, and dark green color crystals of 2-photon absorption compound (D-73) was obtained. The compound had favorable three dimensional refractive index modulation and absorption factor modulation properties. The compound foamed favorably when photons were absorbed.