Optical detection by a La0.67Ca0.33MnO3-y thin-film microbridge

A La0.67Ca0.33Mn3-v (LCMO) thin film has been grown by laser ablation and w as fabricated into a microbridge by conventional photolithography and dry e tching for optical detection. The measured photoresponse, AV, of this LCMO thin-film microbridge reveals that it is bolometric in nature. The photores ponse is linearly proportional to the bias current It, and the power densit y of irradiation W-D, which strongly suggests the applicability of an LCMO thin-film microbridge to a linear optical detector. The ratio of the photor esponse to the irradiated power density, DeltaV/W-D, is independent of the incident-light wavelength lambda from 0.633 to 3.5 mum. The dependence of t he photoresponse on modulated frequency f, follows the DeltaV proportional to f(-0.21) relation. Under I-b = 100 muA and f = 5 Hz at an operating temp erature T-op = 223 K, the responsivity S and noise voltage V-n are 685 V/W and 20 nV . Hz(-0.5), respectively, for this LCMO thin-film microbridge. Fr om the measured S and V-n, the noise equivalent power (NEP) and detectivity D-* were be calculated to be 2.92 x 10(-11) W . Hz(-0.5) and 2.76 x 10(9) cm . Hz(0.5) W-1, respectively, for this LCMO thin-film microbridge. The ex perimental results from this LCMO thin-film microbridge show the practical applicability of this new detector system compared to other established det ectors.