The techniques of optical beam induced current (OBIC) have found wide-spread applications in characterizing many semiconductor and optoelectronic devices. A two-photon confocal microscope is adapted for investigating the dynamics of light emitting devices through the contrast mechanisms of two-photon DC and radio frequency (RF) optical beam induced current (OBIC). For comparison, the 2p-OBIC technique detects the photocurrent signal by exciting the semiconductor sample with a pulsed laser that has a wavelength below the bandgap of the semiconductor. It has high accuracy and spatial resolution. We demonstrate that the bias on the devices (forward and reverse) strongly modifies the DC and RF OBIC signals. Finally we will discuss how to explain this result, and we will provide a program to show the phase distribution of GaP LED.

In this study¡Awe apply the broad bandwidth and high energy pulse of ultrafast laser to experiment on RF OBIC and second harmonic generation. In this paper a novel method is presented for characterizing high frequency response and behavior of ultra high-speed photosensitive semiconductor devices and the set-up is capable of generating excitation at RF bandwidths of greater than 1.8 THz. In addition¡Athe collagen of dentine is able to generate the second harmonic in the ultraviolet region, so we develop a high performance transmission mode laser scanning microscope for obtaining SHG images of a tooth slice. We also study wavelength dependence and polarization dependence.