Patent ID: 7085469

Claim:
A process for producing a three-dimensional polyimide optical waveguide, which comprises: (I) irradiating a polyamic acid film with a laser beam while converging the laser beam at an inside portion of the film and relatively moving the light convergence point, the polyamic acid film containing: (a) a polyamic acid obtained from a tetracarboxylic dianhydride and a diamine; and (b) per 100 parts of the polyamic acid, from 0.5 part by weight to less than 10 parts by weight of a 1,4-dihydropyridine derivative represented by formula (I): wherein Ar represents an aromatic group having a nitro group at an ortho-position with respect to the bonding position to the 1,4-dihydropyridine ring; R 1 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; and R 2 , R 3 , R 4 and R 5 each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms, and then, (II) heating the polyamic acid film to imidize the polyamic acid, thereby obtaining an optical waveguide having a continuous core region where the refraction index has been changed, in the thus formed polyimide film, wherein the laser beam is a pulse laser having a pulse width of 10 −15 to 10 −12 second and the pulse laser has a repeating frequency of from 10 Hz to 500 kHz.