We demonstrate a novel ultra-broad tunable bandwidth and narrow instantaneous line-width swept laser source using combined tunable filters working at 1290 nm center wavelength for application in optical coherence tomography. The combined filters consist of a fiber Fabry-Perot tunable filter (FFP-TF) and a polygon mirror with scanning grating based filter. The FFP-TF has the narrow free spectral range (FSR) but ultra-high spectral resolution (narrow instantaneous bandwidth) driven at high frequency far from resonant frequency. The polygon filter in the Littrow configuration is composed of fiber collimator, polygon mirror driven by function generator, and diffractive grating with low groove. Polygon filter coarsely tunes with wide turning range and then FFP-TF finely tunes with narrow band-pass filtering. In contrast to traditional method using single tunable filter, the trade-off between bandwidth and instantaneous line-width is alleviated. The combined filters can realize ultra wide scan range and fairly narrow instantaneous bandwidth simultaneously. Two semiconductor optical amplifiers (SOA) in the parallel manner are used as the gain medium. The wide bandwidth could be obtained by these parallel SOAs to be suitable for sufficient wide range of the polygon filter’s FSR because each SOA generates its own spectrum independently. The proposed swept laser source provides an edge-to-edge scanning range of 180 nm covering 1220 to 1400 nm with instantaneous line-width of about 0.03 nm at sweeping rate of 23.3 kHz. The swept laser source with combined filters offers broadband tunable range with narrow instantaneous line-width, which especially benefits for high resolution and deep imaging depth optical frequency domain imaging.
From the optical absorption measurements, the Judd-Ofelt parameters were computed using Judd-Ofelt theory. According to the radiative lifetime obtained from the Judd-Ofelt parameters and the measured lifetime, the1.5μm quantum efficiency was calculated. The quenching effect of OH upon the lifetime of 1.5μm emission was investigated. From the absorption sideband measurement of glass host, the value of optical band gap was estimated. The McCumber theory was used to calculate the stimulated emission cross-section and in approximate agreement with experimental one if the emission spectrum could be obtained accurately. The gain coefficient spectra were computed.
The dynamics in the Bose-Einstein Condensation(BEC) process with interaction between two energy-level Bose atoms and single-mode active cavity field in the quantum cavity is analyzed using the ordinary method suggested by the authors for solving the wave function in the Schrodinger ideal from the Heisenberg idea. A wave function has been established for the atoms under the BEC conditions in the quantum cavity. Then the stability factor determining the BEC and the selection rules of the quantum transition can be solved.
The noninvasive measurement of human blood glucose has been a hotspot for a long time to all clinical workers over the world. In this paper the noninvasive measurement of human blood glucose with diffusion reflectance NIR spectrum method is presented. The thumb fingertip, the palm and the wrist with vein are chosen for the collection of diffusion reflectance NIR spectroscopy from six different age healthy volunteers using Nexus-870 and its NIR fiber port smart accessory. The calibration model is set up in 7500~8500cm-1 region that has the absorption of the glucose using Partial Least Squares (PLS) method with the first and second derivative spectral that had been smoothed and baseline corrected for single volunteer. The actual blood glucose value is determined by an ultraviolet spectrophotometer. The model with the spectrum obtained at the wrist is better than from other part for all volunteers, and it is much steadier with the second derivative pretreatment spectral than with the first derivative ones. The correlative coefficients are all over 0.93772; RMSECs are all less than 0.310 and the max differences are between -0.6mmo/L and +0.8mmo/L with the second derivative method. Some samples are kept for prediction with their own model. The differences are under 0.875529mmol/L.
Complex optical system, especially the all-reflecting off-axis spherical system is developed and used in the remote sensing camera and the UVX lithophotography. The alignment becomes more important to such system. In this paper, a computer-aided alignment method is described. The wavefront errors are obtained by using the autocollimating interferometric test at some field of views. A serial of aberrations explained by the coefficients of Zernike polynomials is gotten. They are the object values and will be corrected. The least square method is used to determine the misalignments. This method is demonstrated by the results of numerical simulation. The practical experiments are also given.
A novel method to measure a small angle of optical ray with Talbot image combined with moire technology. The accuracy of the method will reach the 0.04", if we use this method with the opticelectron elements as a receptor.