An all-optical 2R regenerator using a compact self-seeded Fabry-Pe/spl acute/rot laser diode incorporated in a bidirectional EDFA

An all-optical 2R regenerator, based on a compact self-seeded Fabry-Pe/spl acute/rot laser diode with a 10-mm-long embedded fiber Bragg grating cavity, and a bidirectional erbium-doped fiber amplifier, is proposed and experimentally demonstrated to execute all-optical 2R regeneration at 10 Gb/s. Compared with the conventional 1R regeneration, the proposed scheme has achieved significant 6.4-dB improvement of power penalty at bit-error ratio =10/sup -9/ in the transmission experiment over 100-km standard single-mode fiber.     

Hybrid WDM/SCMA-PON using wavelength-locked fabry-Pe/spl acute/rot laser diodes

We propose a large-capacity hybrid passive optical network (PON) with a wavelength-sharing technique achieved by applying subcarrier multiple access on each single channel of a wavelength-division-multiplexed (WDM) PON. We also use forward-error correction to reduce the effect of optical beat interference noise. We demonstrate three-subchannel sharing in a 100-GHz-spaced WDM-PON to accommodate three times more subscribers simultaneously at a fully dedicated connection rate of 125 Mb/s.     

Analysis of fiber fabry-Pe/spl acute/rot interferometric sensors using low-coherence light sources

Sensitivity, fringe contrast, and dynamic range are the three most important parameters in the theoretical performance evaluation of fiber Fabry-Pe/spl acute/rot (F-P) interferometric sensors. This paper theoretically models the effect that the cavity length, the F-P finesse, the source bandwidth, mirror misalignments and symmetry play in the sensitivity, fringe contrast, and dynamic range of a fiber F-P interferometer interrogated with a low-coherence light source. The developed systematic fiber F-P interferometer analysis approach and the numerical analysis results on both guided and unguided fiber F-P interferometer (FFPI) sensors may provide useful guidance for sensor design optimization.     

Generation of wavelength-tunable optical pulses using a linear-cavity fiber laser scheme with a Fabry-Pe/spl acute/rot laser diode

A wavelength-tunable mode-locked linear-cavity fiber laser was demonstrated using a Fabry-Pe/spl acute/rot laser diode. By adding a tunable bandpass filter within the linear cavity, the wavelength-tunable fiber laser was easy to be tuned dynamically. This linear-cavity fiber laser output exhibited a good performance having the optical sidemode suppression ratio over 30 dB and the wavelength-tuning range up to 27 nm. Furthermore, this fiber laser generated pulses with pulsewidth between 53.2 and 80.4 ps at a repetition frequency of 908.39 MHz.     

Color-free operation of dense WDM-PON based on the wavelength-locked fabry-Pe/spl acute/rot laser diodes injecting a low-noise BLS

We demonstrate color-free operation of a dense wavelength-division-multiplexing passive optical network based on the wavelength-locked Fabry-Pe/spl acute/rot laser diodes with injection of a low-noise broadband light source (BLS). The color-free operation, i.e., wavelength-independent operation, was obtained at 50-GHz channel spacing with the help of a narrow injection bandwidth of the low-noise BLS. We also demonstrate three-channel upstream transmission with 100-Mb/s Manchester coded data.     

Rational harmonic mode-locking of erbium-doped fiber laser at 40 GHz using a loss-modulated Fabry-Pe/spl acute/rot laser diode

Rational harmonic mode-locking of an Erbium-doped fiber ring laser (EDFL) at repetition frequency of 40 GHz is demonstrated by using a purely loss-modulated Fabry-Pe/spl acute/rot laser diode (FPLD) at 1 GHz. The FPLD is neither lasing nor gain-switching, which requires a threshold modulation power of 18 dBm to initiate harmonic mode-locking of the EDFL. After chirp compensation, the nearly transform-limited pulsewidth and spectral linewidth of 3 ps and 1.3 nm are obtained at repetition frequency of 40 GHz, which corresponds to a time-bandwidth product of 0.31. The EDFL gradually evolves from harmonic mode-locking to injection-locking mode as the FPLD changes from loss-modulation to gain-switching mode by increasing its dc driving current.     

Optical DPSK demodulator based on /spl pi/-phase-shifted fiber Bragg grating with an optically tunable phase shifter

We propose and demonstrate a novel optical differential phase-shift keying (DPSK) demodulator with an optically tunable phase shifter. The proposed DPSK demodulator is implemented by using a /spl pi/-phase-shifted fiber Bragg grating and an Yb/sup 3+/-Al/sup 3+/ codoped optical fiber. A 10-Gb/s DPSK signal was successfully demodulated by the proposed demodulator, showing clearly open eye diagrams as well as bit-error-free performance. Moreover, the phase of delayed optical signal can be tuned by the phase shifter that is controlled by a pumping light at around 980nm.     

基于嵌入式系统的光纤光栅解调系统的研究

对基于DSP和ARM的光纤光栅解调系统进行研究。针对以DSP,ARM为核心的系统电学部分进行设计;对信号解调算法的软件实现进行研究;最后,叙述了系统整体搭建的情况,同时还分析了对系统进行整体测试的情况,将理论研究运用到实际系统中,得到的实验结果验证了系统的实用性。     

Short multiwavelength fiber laser made of a large-band distributed Fabry-Pe/spl acute/rot structure

Multiwavelength fiber lasers are obtained by writing two superimposed chirped fiber Bragg gratings in a photosensitive Er/sup 3+/--Yb/sup 3+/ codoped optical fiber. The chirped gratings create a distributed Fabry-Pe/spl acute/rot structure in which the resonating fields of the different laser lines are spatially separated, thus, reducing cross-gain modulation. We demonstrate multiwavelength lasers emitting simultaneously over 8 and 16 lines spaced by 50 GHz. The active structure is very compact having a total active length of 8 cm. We discuss how the properties of the device are governed by the parameters of the chirped gratings giving high flexibility in the laser design.     

Multiwavelength tunable fiber ring laser based on sampled chirp fiber Bragg grating

We propose and experimentally demonstrate a novel configuration of a multiwavelength tunable fiber ring laser with equally increased or decreased wavelength spacing. Wavelength tuning is achieved by tuning the strain gradient of a sampled chirp fiber Bragg grating (SCFBG), which is integrated in the laser cavity. To achieve equally increased or decreased wavelength spacing, the SCFBG is surface-mounted at a slant onto one lateral side of a plate so that each wavelength-selective element of the SCFBG will experience an equal strain increment when an external force is applied to the plate. We experimentally obtain seven lasing wavelengths with equally increased or decreased wavelength spacing.     

5-GHz pulsed fiber Fabry-Pe/spl acute/rot laser mode-locked using carbon nanotubes

We demonstrate passive mode-locking of a short-cavity (/spl sim/2 cm) fiber Fabry-Pe/spl acute/rot laser by incorporating a carbon-nanotube-based saturable absorber. Stable pulses are generated with a pulsewidth as short as 0.68 ps at a repetition rate as high as 5.18 GHz. This is the smallest femtosecond fiber pulsed laser ever demonstrated to date.     

基于光纤布喇格光栅的光CDMA编/解码器

介绍了基于光纤布喇格光栅(FBG)的光CDMA编/解码器(E/D),分别给出了非相干光二维FBG编/解码器、振幅调制超结构光纤布喇格光栅(SSFBG)编/解码器、相干光二进制相移键控(BPSK)SSFBG编/解码器、可重构四进制相移键控(QPSK)SSFBG编/解码器的构造方法和最新研究进展,并分析了几种编/解码器的优缺点.     

光纤光栅微型倾角传感器研究

介绍了一种温度不敏感的光纤光栅二维倾角传感器,该传感器是由4个正方形排列的单模光纤组成。首先在两个单模光纤中分别写入两个级联的光纤光栅,并且这两个光纤被固定于两个正交的平面。然后将4个单模光纤粘贴在一起,形成光纤束。最后将合成的光纤束插入陶瓷插芯中,并保证级联的两个光纤光栅分别位于陶瓷插芯内外。通过测量两个级联光纤光栅的中心波长间距,实现二维温度不敏感的倾角传感。实验表明,该传感器在-30°到﹢30°范围内,其中心波长差与倾斜角度数之间满足良好的线性关系,灵敏度为0.017 nm/°,分辨率可达到0.58°。     

A theoretical model of a wavelength-locked Fabry-Pe/spl acute/rot laser diode to the externally injected narrow-band ASE

We propose a theoretical model of the wavelength-locked Fabry-Pe/spl acute/rot laser diode (F-P LD) to the externally injected narrow-band amplified spontaneous emission. The model explains the dynamics of the wavelength-locked F-P LD. The simulation results with the proposed model show good agreement with the experimental results.     

Multiwavelength generation in a Raman fiber laser with sampled Bragg grating

Simultaneous continuous-wave multiwavelength operation of a Raman fiber laser is demonstrated with sampled Bragg grating (SBG) at room temperature. The characteristics of multiwavelength fiber ring laser can be easily controlled by adjusting the parameters of the SBG, including the sampling period and the sampling length. In the proposed fiber laser, stable four oscillating wavelengths with 100- and 50-GHz spacing has been achieved, respectively, as well as five oscillating ones with a wavelength spacing of only 25 GHz by varying the sampling period of the SBG.     

Multiwavelength erbium-doped fiber Fabry-Pe/spl acute/rot laser and its uniform spectral lines power operation

Multiwavelength erbium-doped fiber laser by means of phase modulation in a linear cavity configuration is presented. Stable multiwavelength lasing is achieved by applying any one of the waveforms of sine, square, sawtoothed, and triangular at a suitable frequency between 500 Hz to a few tens of kilohertz to the phase modulator. The output spectral lines power equalization is performed by adjusting the frequency to drive the all-fiber phase modulator and the polarization controller or dc offset voltage of a LiNbO/sub 3/ amplitude modulator, which is incorporated in a polarization-maintaining fiber Lyot-Sagnac filter.     

All-optical four-wavelength 2R regeneration based on data-pump four-wave-mixing with offset filtering

A simultaneous all-optical 2R regeneration of 4 × 12.5 Gb/s return-to-zero (RZ) signals is demonstrated based on the data-pump four-wave-mixing in a single highly nonlinear fiber, in which the channel spacing and duty cycle are 200 GHz and 50%. Both the bidirectional configuration and time-interleaved technology are used to reduce the crosstalk from other channels. For further improving the performance of the multichannel regenerator, an offset filtering (OF) method is employed to minimize the influence from the opposite input signal. Our experiments show that the extinction ratio (ER) of regenerated signals is about two times larger than that of the degraded signals and the maximum ER improvement is about 6.5 dB. By using the offset filtering method, the sensitivity improvements of four-wavelength regenerated signals are 2.05 dB, 2.53 dB, 3.57 dB and 2.8 dB, respectively.     

All-optical 2R regeneration based on integrated asymmetricMach-Zehnder interferometer incorporating MMI-SOA

2R regeneration is proposed with an integrated Mach-Zehnder interferometer containing a monomodal semiconductor optical amplifier (SOA) and an SOA with a 1 × 1 multimode interference (MMI) coupler-SOA in the arms. Simulations and measurement of the static transfer function show a digital shape with a high extinction ratio improvement     

Electrooptic temperature sensor based on a Fabry-Pe/spl acute/rot resonator with a liquid crystal film

An electrooptic (EO) temperature sensor based on a Fabry-Pe/spl acute/rot (FP) resonator with a nematic liquid crystal (NLC) film is proposed. A novel compensation scheme of the EO effect allows for precise determination of temperature by monitoring the resonant wavelength of the NLC FP sensor. The proposed EO temperature sensor provides good stability, high resolution, self-calibration capability, and low driving voltage.     

Tunable dispersion compensator based on a fiber Bragg grating written in a tapered fiber

We report a novel dispersion tunable device for first-order dispersion compensation. It is based on a fiber Bragg grating written in a tapered fiber with a specific profile. The taper profile allows tuning the dispersion of the grating by stretching the fiber while the linearity of the group delay is preserved. A device with 0.8 nm of useful bandwidth and dispersion value tunable over more than 400 ps/nm is reported.