This work was supported by the National Natural Science Foundation of China(Grant Nos.10074033 and 10274032);the N ational Natural Science Foundation of Jiangsu Province(BK2004081);SRF for ROCS.SEM.and TWAS(No.03-390).
Subharmonics or ultraharmonics provides better contrast-to-tissue ratio (CTR) than the fundamental or the second harmonics, having prospective application in medical diagnosis. In this paper, subharmonic and ultra-har...