MFs with three zero-dispersion wavelengths are studied and designed by multi-pole method. Phase mismatch of this kind of MFs with d/Λ=0.40, Λ=1.8μm is studied when pump locates at all three zero-dispersion wavelengths and the wavelengths of some commonly used lasers. Numerical results show that broadband phase match can be achieved when the pump varies from the normal dispersion regime around the first zero-dispersion wavelength to the last zero-dispersion wavelength and two sets of phase matched wavelengths exist when the wavelengths of pump are in the anomalous dispersion regime between the first two zero-dispersion wavelengths. Then, a little air-hole is added in the fiber core and the dispersion characteristics of the new MFs are investigated for MFs with four zero-dispersion wavelengths. The phase matching topology of this kind of MFs with d/Λ=0.80, Λ=2.2μm, d0=0.636μm is analyzed when the pump is in the anomalous dispersion regime, zero-dispersion wavelength and normal dispersion regime of the fiber. Two sets of phase matched wavelengths can also be found when the MF is pumped in the anomalous dispersion regime between two neighboring zero-dispersion wavelengths. Interestingly, when the MF is pumped in the normal dispersion regime between the second and third zero-dispersion wavelength, three phase matched wavelengths sets appear. For MFs with multiple zero-dispersion wavelengths mentioned above, in entire phase matching band, there always exists one Stokes wave whose wavelength is longer than the longest zero-dispersion wavelength of the fiber, which will provide more possibilities for frequency conversion in mid-infrared band.
Detection of biological samples in low concentration is of great significance to the basic research in science, the
development of medical technology and many other fields related to our lives. Surface-Enhanced Raman Scattering
(SERS), well-known as a powerful analytical tool with high sensitivity, is especially suitable for biomolecule detection
as it enables near infrared (NIR) excitation and label-free detection. SERS probe made of conventional optical fiber
provides better flexibility in detection; however, it requires a complicated fabrication process and doesn't serve as a
well-set detecting platform. In this talk we propose and demonstrate a photonic crystal fiber (PCF) based SERS probe,
which has the new advantages of simplicity in fabrication, better light confinement and increased light-analyte
interaction volume. The PCF-based SERS probes are prepared in three different ways: mixed solution of sample and
gold nanoparticles filled in air holes of PCF, sample solution dried in gold coated air holes and sample solution filled in
gold coated air holes, respectively. Sample solution of adenine is in concentration of about 10-6M. Almost every
characteristic peak of adenine can be observed in the spectra detected by each of the three probes.
We present the design of an imaging fiber bundle lens that consists of an objective lens and a coupling lens. The objective lens has an operating wavelength of 0.4 to 0.7 µm, a field of view of 60 deg, and an outer diameter of 9.5 mm. The coupling lens has an operating wavelength of 0.4 to 0.7 µm, a field of view of 6 mm, and an outer diameter of 7.7 mm. The imaging quality of an imaging fiber bundle lens has been experimentally demonstrated.
In this paper the photonic crystal fiber (PCF) with square-lattice array in a silica matrix has been put forward. The PCFs studied in this paper have a solid core, obtained by introducing a defect that is by removing two holes at the center of the fiber cross section and with smaller air-holes in the same direction. For the different wavelengths in the range between 700 nm and 1600 nm, the effective index neff of the PCF fundamental mode has been obtained by the fast multipole method. The model field, birefringence, and confinement loss of the fibre fundamental mode are simulated. It is found that lower confinement loss and higher birefringence can be realized in the condition of fewer rings of air holes. The simulation results in this paper are important for instructing the fabrication of birefringent photonic crystal fibers.
The Stacking-capillary Method is widely used in the fabrication of the Micro-structure Fiber (MSF). We describe an improved stacking-capillary method, which can fabricate the MSF without interstitial holes. The method includes several steps. Firstly, the MSF preform is made by the stacking-capillary method; secondly, the MSF preform is put into the high temperature furnace to heat at 1600°, then the positive pressure is produced into the capillaries by adding air, every three adjacent capillary holes are expanded in the preform, and the interstitial holes are eliminated, all the capillaries are fused together, although the round capillary have changed to hexagon, the size of the prefrom does not change, and still keeps very good structure. The step of eliminating the interstitial hole can help to keep the MSF structure during drawing fiber. We get well results by the Improved Stacking-capillary Method.
A brief description on the optical path and circuit of the IR system is presented. After analyzing the behavior of the pyroelectric detector detecting instrument response to the radiation, a complex performance parameter automated measurement system is put forward. And the response time is measured by the step response method, which founded the experimental basis for the detecting instrument's correct operation.
A new type of the double layers polycrystal dielectric film in the quartz capillary has been fabricated. The first film is composed of nanoscale germanium dioxide obtained from controlling reaction temperature, gas flow rate and the proportion of reactants, and the second film is metal layer that has high refractive index at infrared region. So the dual-layer thin film has very high reflectivity at the wavelength range of 8-11 .6 µ m. The hollow-core optical fiber with this film on inner wall can transmit over 400 watts of cw carbon dioxide laser power or the pulse carbon dioxide laser with pulse width of 0.1 second and peak-power of 1000 watts, and transmission loss is less than O.6dB/m at 10.6 µ m in transmitting high power. The transmitting laser power fibers can be applied in medical treatment, mechanical process or the relevant scientific research etc.