Biomedical subjects

Yinchieh Lai

Publications and source records attributed to Yinchieh Lai.

5 recordsLinked to original sources

PubMed2006

Tunable Er3+-doped fiber amplifiers covering S and C+L bands over 1490-1610 nm based on discrete fundamental-mode cutoff filters.

We demonstrate thermo-optically tunable Er3+-doped fiber amplifiers covering S and C+L bands (1490-1610 nm) using fundamental-mode cutoff filters discretely located in a 17.5 m long standard Er3+-doped fiber. The material dispersion and waveguide structure of the tapered fibers are locally modified to produce high-cutoff-efficiency filters that make the unwanted amplified spontaneous emission highly attenuated at the longer wavelengths, and the optical gain is thus moved toward the shorter wavelengths. The maximal signal gains are measured to be 18.92, 37.18, and 15.19 dB with 980 nm pump power of 135 mW in the S, C, and L bands, respectively.

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PubMed2006

Stable new bound soliton pairs in a 10 GHz hybrid frequency modulation mode-locked Er-fiber laser.

We report what is, to our knowledge, the first experimental observation of stable new bound soliton pairs at the 10 GHz repetition rate in a hybrid FM harmonic mode-locked Er-fiber laser (1177 soliton pairs simultaneously in the laser cavity). The two solitons in the soliton pair have the identical pulse shape and are with the antiphase (pi phase difference). Their time separation is about three times the FWHM soliton width and varies with the phase modulation strength. The corresponding mechanism for explaining the formation as well as the superior stability of these closely bound soliton pairs is also given.

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PubMed2005

Photon-number fluctuation and correlation of bound soliton pairs in mode-locked fiber lasers.

Quantum photon-number fluctuation and correlation of bound soliton pairs in mode-locked fiber lasers are studied on the basis of the complex Ginzburg-Landau equation model. We find that, depending on their phase difference, the total photon-number noise of the bound soliton pair can be larger or smaller than that of a single soliton, and the two solitons in the soliton pair have a corresponding positive or negative photon-number correlation. It is predicted for the first time to our knowledge that out-of-phase soliton pairs can exhibit less noise as a result of negative correlation.

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PubMed2005

Direct generation of a 10 GHz 816 fs pulse train from an erbium-fiber soliton laser with asynchronous phase modulation.

By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers.

Journal Article↗

PubMed2004

Complex fiber grating structures fabricated by sequential writing with polarization control.

We propose a flexible method for fabricating complex fiber grating structures based on sequential writing for fiber gratings with polarization control of the UV source beam. Pure apodized as well as arbitrary phase-shifted fiber Bragg gratings (FBGs) can be fabricated in a single scan. Experimental examples of raised-cos2 apodized and dispersionless FBG filters are given to demonstrate the feasibility of this method.

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