The reflecting wavelength shift of fiber Bragg grating (FBG) can be caused by the variations of both strain and temperature, and such a so-called cross sensitivity is a "bottle-neck" which limits the FBG sensing and measuring technique to put into practical application. The measurement error is caused by the temperature change to measure the strain-inducing Bragg wavelength shift. The basic theory of temperature compensation of fiber Bragg gratings is presented according to the physical mechanisms of the strain and temperature cross sensitivity. A passive compact package for compensating the temperature dependence of FBG, based on the use of two materials with different thermal expansion coefficients, has been demonstrated. Two ends of the tensioned fiber grating are attached to the organic glass with epoxy resin. As the temperature rises and the strain is progressively released, it compensates the temperature dependence of the Bragg wavelength. The relation between temperature and wavelength in different compensation condition and in different strain is given. And the reason of undercompensation or overcompensation of the FBG is also analyzed. The Bragg wavelength shift over the temperature range of -19°C to 60°C is 0.79 nm for the uncompensated FBG, and that of the compensated FBG is only 0.035 nm for uncompensated FBG, which is 1/22 of that of the uncompensated FBG.
Fabricated by four times H+ inclined implantation using tungsten wire as mask, batch vertical cavity surface emitting lasers with better characters than those of common ion implanted devices were obtained. They have the batch threshold current of less than 1.5mA, the lowest threshold current of 1.2mA which is lower than that of common oxide confinement device product, the largest light output power of about 1mW with simple TO package, and the largest 3dB modulation bandwidth of 4GHz. According to the polarization measurement result, the devices showed good 0° linear polarization character and up to 14dB polarization suppress ratio in the whole linear gain region, which is better than that of common oxide confinement devices. Spectrum measurement result showed that their wavelength was around 835nm, and they operated with single transverse mode in linear gain region. Furthermore, the fabrication technology was simple enough for the industry without photolithography and lift-off steps.
We had fabricated a 1.5μm tilted superluminescent diode (SLD) integrated with a semiconductor optical amplifier (SOA). High superluminescent power 70mW was obtained at lower pumping level
by co-operation of the two sections under pulse condition. The spectral FWHM is 23nm.
We built a test system to pick up the pattern of light beam from the VCSELs and the EL spectrum simultaneously in order to study the mode behavior when the current applied on the device increased. As a result, we observed that the light spots from the VCSEL seemd to be high-order-mode while its EL spectrum included more than one peak
wavelength. Comparing it with the high-order-mode case that we met and defined in VCSELs before, we considered that the mode we observed this time was different from the true high-order-mode in essence. We named it as pseudo-high-order-mode and gave the explanation.
The PCF with triangular lattice structure has the C, symmetry, the fundamental guided mode belongs to the C group, the third order guided mode belongs to the D31 group, we can simplify the computation by selecting the proper expend functions according to the symmetry ofthe modes. We have calculated the dispersion ofthe PCF with triangular structure and find the proper structure parameter with which the dispersion of fundamental mode at 1 .55jim can be zero. We also calculated the magnetic distribution of the third order guided mode of honeycomb-based PCF and proved that the interstitial holes in the PCF has no effect on the mode distribution.
In this paper, we deposited high quality ZnO film by plasma-assisted Metal-organic Chemical Vapor Deposition (MOCVD). A dominant peak at 34.6 degree due to (002) ZnO was observed indicating strongly C-oriented. The full-width at half-maximum (FWHM) of the (-rocking curve was 0.56 degree showing relatively small mosaicity. Transmission spectrum showed that the bandgap of ZnO film was about 3.31 eV at room temperature. Photoluminescence (PL) measurement was performed at both room temperature. Ultraviolet (UV) emission at 3.30 eV was found with high intensity at room temperature while the deep level transition was weakly observed at 2.513 eV. The ratio of the intensity of UV emission to that of deep level emission was as high as 193, which implied high quality of ZnO film. The resistivity of ZnO film was increased after annealing under Oxygen while its optical quality decreased.
No annealed, annealed after growth and annealed during growth ZnO films (denoted s1,s2, and s3 respectively) were grown on C-plane sapphire substrate by plasma-enhanced MOCVD and characterized by XRD and the optical transmission spectra. We could find that there is tensile strain in the c-plane of the films. Furthermore, the tensile strain increases after annealing. At the same time, the optical transmission indicates that the transmission of s2 in visible region is the highest and the value of s3 is the lowest.
In the paper, a thin tensile GaAs interlayer was used to get regular arrangement of InAs quantum dots (QDs) on InP substrate by LP-MOCVD. Photoluminescence (PL) spectrum, atomic force microscopy (AFM) image and Raman spectrum have been investigated. The five band k(DOT)p formalism in the PL spectrum and frequency shift in Raman spectrum have been performed. The theoretical calculations coincide with our experiment results well. The density of InAs quantum dots at 4 ML InAs is the maximum (1.6X1010cmMIN2).
Optical bistability with 100 ps switching time has been observed in ZnS/ZnSe stratified grating filter at room temperature for the first time. We think that the optical bistability results from the band-filling effect caused by the nonlinear absorption of the material and reflection occurred among the multilayer films. When the light intensity is larger enough. The refractive index change will be larger and the transmitted light intensity increases remarkably owing to the third order nonlinear effect of ZnS/ZnSe, so ZnS/ZnSe stratified grating is of optical bistability.
A few kinds of waveguide materials and optical waveguide technology was studied and all kinds of optical waveguide devices and their applications were reviewed in this paper.
Superluminescent light sources can be used in many fields, such as fiber optics gyroscope, optical time domain reflector, wavelength division multiplexing system, in which superluminescent power is very important factor. In order to increase the power, we integrated the SLD and SOA monolithically. Meanwhile, the axis of integrated device was tilted with respect to the facet normal. High power 1.5 micrometers superluminescent light source has been fabricated by optimizing the structure of integrated device. More than 200mW was obtained at lower pumping level by cooperation of the two sections. The spectral FWHM is 26nm.
The photoluminescent properties of an optical microcavity formed by a single layer of PPV film sandwiched between a quarter-wavelength distributed Bragg reflector and a metal Ag reflector was studied. The significant microcavity effect was observed. (1) The PL emission spectrum of PPV film is a wide band spectrum with two peaks at 510 nm and 550 nm, respectively. The PL emission spectrum of the microcavity shows 2 peaks, which is at 564 nm and 599 nm, respectively. The FWHM of the narrowed emission spectrum is 7 nm. The PL emission intensity of the microcavity at the resonant mode of 564 nm is enhanced by 19 times. (2) It was found that the peak of the microcavity is blue-shifted with the decreasing of emission intensity obviously when the detection angle is increased. We consider that this is a novel phenomenon and worth investigating further.
A high power superluminescent diode (SLD) is developed on the basis of the terraced substrate inner laser diodes. The device is made of the characteristic of LPE of crystal on the non- planar substrate. The device's output power before assembled is 7 mW under operating current 150 mA. The wavelength is about 860 nm. The half width of the spectrum is 23 nm. The device is coupled with fiber (NA equals 0.23, D equals 50 micrometer). The coupling efficiency is about 30%. The pigtail fiber maximum output power is 2 mW.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.