Fang Zujie

Sampled FBG based optical interleaver

In this text, we propose a novel optical interleaver using sampled fiber Bragg grating. According to coupling-mode theory, the interleaver based on sampled fiber Bragg grating with low sampling duty cycle may realize separate odd and even channel into two groups with power equalization, low insertion loss, and low dispersion.

Study on the protection of Er-doped phosphate glass waveguide surface in ion-exchange processing

A novel method, sputtering K9 glass film, is proposed to solve the surface corrosion of Er-doped phosphate glass during ion-exchange processing for optical waveguide fabrication. The corrosion causes are analyzed to be the intrinsically weak stabilization of phosphate glass structure, hydrophile and weakly acidic property of phosphate radical. Experimental results show that the K9 glass film could not only protect the Er-doped phosphate glass surface from being corroded but also give no influence on the waveguide fabrication. The effect of thickness of K9 glass film on the optical property of waveguide is also investigated and the optimal thickness is found to be 60–80 nm. It provides a good base for further fabrication of active phosphate glass optical waveguide devices.

All-fiber Q-switched erbium laser using a fiber Bragg grating placed in loop mirror as a wavelength-selective intensity modulator

Summary form only given. We have demonstrated, for the first time to our knowledge, operation of a novel Q-switched erbium doped fiber laser using a fiber Bragg grating placed in loop mirror (FBGLM) as an all-fiber wavelength-selective intensity modulator. The main advantage of this FBGLM modulator is that it provides not only the ability to adjust the reflectivity of the cavity mirror but also the ability of wavelength selection. Stable optical pulse output with 3 dB linewidth of 0.07 nm, pulse width of 1.0 /spl mu/s, and peak power of 1.267 W at 80 mW pump power and 8 KHz repetition frequency was obtained in experiments.

Composite second-order performance improvement in optical fibre CATV transmission system using chirped fibre grating

Theoretically, we analyse the dispersion compensation characteristics of the chirped fibre grating (CFG) in an optical fibre cable television (CATV) system and obtain the analytic expression of the composite second-order (CSO) distortion using the time-domain form of the field envelope wave equation. The obtained result is in good agreement with the numerical simulation result. Experimentally, we verify the result by making use of the tunable characteristics of CFG to change the dispersion compensation amount and obtain an optimal CSO performance in a 125km fibre transmission link. Both the theoretical and experimental results show that the CSO performance can be improved by properly choosing the dispersion compensation amount for a certain fibre transmission link.

785Nm external cavity Laser Diode with volume Bragg grating used in Raman spectroscopy

A 785nm external cavity laser diode with volume Bragg grating (VBG) used in Raman spectroscopy was presented. In order to improve the performance of Raman signal, the line-width of Laser diode (LD) is narrowed by external cavity technology and VBG, and the beam is also shaped by aspheric lens and fast-axis-collimator.

Study on wavelength distribution of high power laser diode array

Measured lateral wavelength distribution of LDA is presented, showing typically a V-type feature. Analyses indicate it is induced by bonding stress. A linear distributed stress model is proposed to explain the experimental results.

Experimental study of the wavelength locked of the high power laser diode bar

An external cavity laser diode was built by using a high power laser diode bar (LDB, 10% duty cycle, 100 A current), collimated column Len for fast axis beam collimation and a volume Bragg grating (VBG) as a feedback element to get LDBs wavelength locked to the Bragg wavelength of the VBG.

Study of WDM polymer planar curved waveguide couplers

A wavelength division multiplexer based on curved polymer planar waveguide is proposed. According to the coupled mode theory and the waveguide structure, the performance of the curved waveguide coupler (CWC) is analyzed. The results show that CWC can accommodate wider multiplexing bandwidth than parallel straight waveguide coupler (SWC) due to the compensation effect of the effective coupling length. The two variables, curvature radius and minimum spacing, increase the design flexibility of the waveguide device. A 4-channel wavelength division multiplexing (WDM) system based on CWC is designed. The deviation of the center wavelength, due to the errors of curvature radius and minimum spacing during fabrication process, is investigated. The smaller the curvature radius and the minimum spacing are, the larger the central wavelength deviation caused by the error of the curvature radius and the minimum spacing is, which provides some useful theoretical basis for the design and the fabrication of polymer waveguide devices.