We describe a high isolation thin-film filter coated on a GRIN lens surface for triple-play services. High isolations of 60
dB and 43 dB between 1480 nm and 1550 nm bands in transmittance and reflection ports are achieved by use of
originally developed ion-beam sputtering deposition machine.
A fiber directional coupler is very often used as the interferometer for optical coherence tomography (OCT). In this paper, we present, for the first time to our knowledge, the experimental result showing influence of wavelength dependence of the fiber interferometer on the axial resolution of OCT in the wavelength region of 0.8 and 1.3/1.5μm.
We describe the spatial mode-matching of a diode-pumped Nd:YAG laser to a ring mode-cleaner cavity with an efficiency as high as 99.8%. Spatial-mode coupling including thermal-lensing effects in the cavity are analyzed.
We describe frequency stabilization of two laser-diode-pumped Nd:YAG lasers independently locked to two high-finesse Fabry-Perot cavities. The frequency noise is reduced to the shot noise limit of 0.37 mHz/(root)Hz at the error signal. A heterodyne beat note between two locked lasers is used to measure the frequency stability, and the beat linewidth of 16 Hz and the root Allan variance of 19 Hz at time interval of 3 ms are measured. A new scalable geometry of multi-LD-pumping for high power and TEM00 output solid state lasers have been developed. The principle of virtual point source clad pumping system is discussed in terms of analytical and numerical calculations. A prototype model was developed by using 32 X 1 W - fiber-coupled LD. The center core of 200 micrometers diameter of 2-mm YAG rod was excited efficiently. The transverse mode of output was controlled simply by changing the ratio of excitation volume to cavity mode volume. The high power version of 320 W pumping is designed and appear in the near future.
The development of frequency stabilized lasers related to the gravitational wave detection is reported. The beat linewidth of laser diode pumped YAG lasers stabilized to the same cavity was measured to be 193 mHz. The source of frequency fluctuation was analyzed carefully. For the higher sensitivity for gravitational wave detection new designs, 100 micrometers thick YVO4 active mirror and virtual source clad pumping YAG lasers are discussed from the view of scaling physics.