排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
Because it avoids the in-focus photodamage and phototoxicity problem of two-photon-fluorescence excitation, multiharmonic-generation biopsy based on a 1200-1300-nm light source could provide a truly noninvasive and highly penetrative optical sectioning of skin. We study multiharmonic-generation biopsy of fixed mouse skin. Our preliminary study suggests that this technique could provide submicrometer-resolution deep-tissue noninvasive biopsy images in skin without the use of fluorescence and exogenous markers. 相似文献
2.
Sun Chi-Kuang Huang Yong-Liang Liang Jian-Chin Wang Jiun-Cheng Gan Kian-Giap Kao Fu-Jen Keller Stacia Mack Michael P. Mishra Umesh Denbaars Steven P. 《Optical and Quantum Electronics》2000,32(4-5):619-640
We have studied third order nonlinearities, including two-photon absorption coefficient and nonlinear refractive index n
2, of GaN in below bandgap ultraviolet (UV) wavelength regime by using UV femtosecond pulses. Two-photon absorption was investigated by demonstrating femtosecond UV pulsewidth autocorrelation in a GaN thin film while femtosecond Z-scan measurements revealed information for both n
2 and . The distribution of n
2 versus wavelength was found to be consistent with a model described by the quadratic Stark effect, which is the dominant factor contributed to the nonlinear refractive index near the bandgap. Large on the order of 10 cm/GW and large negative n
2 with a magnitude on the order of several 10–12 cm2/W were obtained. The at near mid-gap infrared (IR) wavelength was also found to be on the order of several cm/GW by using two-photon-type autocorrelations in a GaN thin film. Taking advantage of the large two-photon absorption at mid-gap wavelengths, we have demonstrated excellent image quality on two-photon confocal microscopy, including two-photon-scanning-photoluminescence imaging and two-photon optical-beam-induced current microscopy, on a GaN Hall measurement sample and an InGaN green light emitting diode. 相似文献
3.
Received October 14, 2005; revised January 7, 2006; accepted January 9, 2006; posted January 12, 2006 (Doc. ID 65391) The two-photon excitation action cross section of Hc-Red fluorescent proteins (Hc-RFPs) is measured and found to be of the same order as that of enhanced green fluorescent proteins. With a 618 nm emission wavelength in the far-red region and with an excitation wavelength around 1200 nm, Hc-RPF-based two-photon fluorescence microscopy (2PFM) can offer deep penetration capability inside live samples and is ideal for in vivo gene expression study and biomolecular imaging in live objects. In vivo 2PFM of the developing heart deep inside a transgenic zebrafish embryo tagged by Hc-RFP is also successfully demonstrated. 相似文献
4.
Low-loss subwavelength plastic fiber for terahertz waveguiding 总被引:2,自引:0,他引:2
We report a simple subwavelength-diameter plastic wire, similar to an optical fiber, for guiding a terahertz wave with a low attenuation constant. With a large wavelength-to-fiber-core ratio, the fractional power delivered inside the lossy core is reduced, thus lowering the effective fiber attenuation constant. In our experiment we adopt a polyethylene fiber with a 200 microm diameter for guiding terahertz waves in the frequency range near 0.3 THz in which the attenuation constant is reduced to of the order of or less than 0.01 cm(-1). Direct free-space coupling efficiency as high as 20% can be achieved by use of an off-axis parabolic mirror. Furthermore, all the plastic wires are readily available, with no need for complex or expensive fabrication. 相似文献
5.
An electric-field-induced second-harmonic-generation signal in a nematic liquid crystal is used to map the electric field in an integrated-circuit-like sample. Since the electric-field-induced second-harmonic-generation signal intensity exhibits a strong dependence on the polarization of the incident laser beam, both the amplitude and the orientation of the electric field vectors can be measured. Combined with scanning second-harmonic-generation microscopy, three-dimensional electric field distribution can be easily visualized with high spatial resolution of the order of 1 microm. 相似文献
6.
Multiplying the repetition rate of passive mode-locked femtosecond lasers by an intracavity flat surface with low reflectivity 总被引:1,自引:0,他引:1
By inserting a low-reflectivity flat surface inside the oscillator cavity, we demonstrate a flexible and phase-insensitive method for multiplying the repetition rate of a femtosecond passive mode-locked solid-state laser. Without mode matching and feedback control, we successfully multiplied the repetition rate of a passively mode-locked Cr:forsterite laser from 124 MHz to 1.24 GHz. High-repetition-rate femtosecond optical pulses with average power of >100 mW can be obtained with the demonstrated method. 相似文献
7.
Spectral characteristics of laser-generated acoustic waves in an InGaN/GaN superlattice structure are studied at room temperature. Acoustic vibrations in the structure are excited with a femtosecond laser pulse and detected via transmission of a delayed probe pulse. Seven acoustic modes of the superlattice are detected, with frequencies spanning a range from 0.36 to 2.5 THz. Acoustic waves up to ∼2 THz in frequency are not significantly attenuated within the transducer which indicates excellent interface quality of the superlattice. The findings hold promise for broadband THz acoustic spectroscopy. 相似文献
8.
By measuring the spectral loss characteristics of subwavelength-diameter terahertz fibers, our study supports the recent theory proposed by M. Sumetsky [Opt. Lett. 31, 870 (2006)] that diameter-variation-induced radiation is a dominant loss mechanism for subwavelength fibers in the low- (<1%) core-fraction-power regime. This physical mechanism limits the lowest guidable frequency in a subwavelength fiber. 相似文献
9.
Ko-Shao Chen Pei-Yu Liu Shu-Chuan Liao Hong-Ru Lin Chi-Kuang Feng 《Applied Surface Science》2009,256(4):1101-1105
Low temperature process to prepare titanium oxide film on the surface of PET was investigated in this study. The substrates were pre-treated by oxygen plasma activated procedure, and then spin coating of Ti(OR)4 precursor solution was carried out to prepare Ti-containing organic films. Finally, O2 plasma was employed to decompose organic compounds and oxidize Ti to form oxides. Oxygen plasma post treatment can oxidize the organic compounds to form titanium oxide carbon subsequently. From the IR and ESCA analysis could be observed that -CH bond decreases and Ti-O, C-O bonds increase after O2 plasma treatment. Their surface hydrophilicity was enhanced by UV-irradiation, the degree of water contact angle decreased from 60° to 10°. 相似文献
10.
Biocompatible bacteria@Au composites for application in the photothermal destruction of cancer cells
Kuo WS Wu CM Yang ZS Chen SY Chen CY Huang CC Li WM Sun CK Yeh CS 《Chemical communications (Cambridge, England)》2008,(37):4430-4432
We have successfully transformed the infectious E. coli bacteria into biocompatible bacteria@Au composites for photothermal therapy. 相似文献