a new sensitive, simple and rapid method for determination of methotrexate (mtx) was developed based on quenching effects of mtx on the fluorescence intensity of tb3+-1,10-phenanthroline complex. the fluorescence intensity was measured with excitation wavelength of 300 nm and emission wavelength of 545 nm and the quenched fluorescence intensity is proportional to the concentration of mtx in tris...

A novel velocity-matched distributed balanced photodetector operating at 1.3 and l.55p.tm wavelengths has been experimentally demonstrated. Distributed absorption and velocity matching ofthe optical and microwave signals are employed to achieve high saturation photocurrent. A common mode rejection ratio greater than 27 dB has been achieved over a wide range of photocurrents. More than 24dB supp...

A theoretical analysis has been undertaken of the steady state transverse mode selection in Vertical Cavity Surface Emitting Lasers (VCSELs) subject to optical feedback in an external cavity connguration. Proper account is taken of multiple re-ections in the external cavity. The innuence of thermal eeects on the mode selection is also treated and noise properties of the connguration are discuss...

We present a new, alternative approach to realize a wavelength swept light source with no fundamental limit to sweep speed. Amplified spontaneous emission (ASE) light alternately passes a cascade of optical gain elements and tunable optical bandpass filters. We show that for high sweep speeds, the control signal for the different filters has to be applied with a defined, precise phase delay on ...