Zuowei Yin

Experimental demonstration of distributed feedback semiconductor lasers based on reconstruction-equivalent-chirp technology

In this paper we report, to the best of our knowledge, the first experimental realization of distributed feedback (DFB) semiconductor lasers based on reconstruction-equivalent-chirp (REC) technology. Lasers with different lasing wavelengths are achieved simultaneously on one chip, which shows a potential for the REC technology in combination with the photonic integrated circuits (PIC) technology to be a possible method for monolithic integration, in that its fabrication is as powerful as electron beam technology and the cost and time-consuming are almost the same as standard holographic technology.

Multilongitudinal mode fiber laser for strain measurement

A multilongitudinal mode fiber laser sensor formed by two fiber Bragg gratings and a piece of erbium-doped fiber is first proposed and validated experimentally. When the strain is applied on the sensor, the laser cavity is stretched, which leads to a change of round-trip frequency. Thus the strain can be obtained by measuring the beat frequency of the resonant cavity. The proposed sensor is found to be characterized with simplicity, easy setup, high resolution, low-cost demodulation, and good stability. Experimental results show that the sensor has a sensitivity of -1.1 KHz/microepsilon and the root-mean-square deviation of 3.6 microepsilon.

Fiber Ring Laser Sensor for Temperature Measurement

A novel multi-longitudinal-mode fiber ring laser temperature sensor based on the beat frequency demodulation technology is presented. The beat frequency between any two modes varies linearly with the temperature. It is experimentally demonstrated that the temperature can be measured with a sensitivity of 10.24 kHz/° C @ 1581.7 MHz between 21° C to 50 ° C, 7.42 kHz/° C @ 1175.6 MHz between 22 °C to 240 °C and 8.48 kHz/° C @ 1480.5 MHz between 100 °C to 1000 °C. This method offers a simple scheme for fiber temperature sensing by employing a low-frequency electrical frequency spectrum analyzer.

Fiber-Optic Vibration Sensor Based on Beat Frequency and Frequency-Modulation Demodulation Techniques

In this letter, a novel multilongitudinal mode fiber-optic vibration sensor is presented. The beat frequency of any two different laser modes is modulated by the vibration signal. The modulated beat frequency signal can be demodulated by a frequency-modulation demodulator. It is demonstrated that the vibration from 60 Hz to 20 KHz can be measured successfully. The sensor has high sensitivity and high signal-to-noise ratio, especially between 500 Hz and 7.4 KHz.

A Multiexposure Technology for Sampled Bragg Gratings and its Applications in Dual-Wavelength Lasing Generation and OCDMA En/Decoding

In this letter, a multiexposure technology for sampled Bragg gratings is proposed and investigated for the first time. Combined with reconstruction-equivalent-chirp technology, the useless zeroth-order channel can be eliminated and the plusmn1st-order channels can be enhanced significantly. The proposed method is applied experimentally to achieve a dual-wavelength fiber laser and is studied both numerically and experimentally in two ways for the optical code-division multiple access en/decoding system. Its properties may lead to more efficient design and fabrication of grating-based optical devices.

Simultaneous Measurement of Strain and Load Using a Fiber Laser Sensor

There are longitudinal-mode beat frequency and polarization-mode beat frequency in the beat frequency spectrum of a fiber laser. Thus, a fiber laser sensor for simultaneous measurement of strain and load by monitoring both the longitudinal-mode beat frequency and polarization-mode beat frequency is proposed and demonstrated in this paper. The maximum experimental errors of strain and load obtained are within and g over ranges of 0-960 and 0-600 g. The presented method makes full use of the sensing information of the fiber laser sensor and improves its sensing ability significantly.

Dual-Wavelength FBG Laser Sensor Based on Photonic Generation of Radio Frequency Demodulation Technique

Based on the radio frequency (RF) demodulation technique, a novel dual-wavelength fiber laser sensor is proposed and demonstrated experimentally. A beat sensing signal, which is generated by the coherently mixing output of a dual-wavelength laser in a high frequency photodetector, has been obtained and demodulated by a radio-frequency spectrum analyzer (RFSA). By employing a LiNbO3 modulator, high-frequency beat signal can be tuned arbitrarily to tens or hundreds of megahertz without distortion and thus a lowfrequency RFSA can be used. When a strain is applied on the laser sensor, the detected beat signals will be shifted with a strain sensitivity of about –8.11 kHz/με.

Multilongitudinal mode fiber-ring laser sensor for strain measurement

A multilongitudinal mode fiber ring laser sensor is proposed and experimentally demonstrated by measuring the strain applied on the laser sensor head. The ring cavity of the laser is formed by a 3-dB coupler, a section of erbium-doped fiber, and one fiber Bragg grating. Photonic generation of beat signals and strain measurement theory are discussed in detail. The strain applied on the fiber ring cavity is obtained by measuring the beat frequency shift. The selection way of the optimal beat signal for strain measurement is obtained by experimental research and discussion. The root-mean-square deviation of the strain and the response of beat frequency to the strain are 2.7 μɛ and 1.5 kHz/μɛ at 1993 MHz, respectively. The proposed sensor scheme offers a cost-effective and high-stability device for strain measurement.

Simple hybrid wire-wireless fiber laser sensor by direct photonic generation of beat signal.

Based on direct photonic generation of a beat signal, a simple hybrid wire-wireless fiber laser sensor is proposed. In the sensor, an improved multilongitudinal modes fiber laser cavity is set up by only a fiber Bragg grating, a section of erbium-doped fiber, and a broadband reflector. A photodetector is used to detect the electrical beat signal. Next, the beat signal including the sensor information can access the wireless network through the wireless transmission. At last, a frequency spectrum analyzer is used to demodulate the sensing information. With this method, the long-distance real-time monitor of the fiber sensor can be realized. The proposed technique offers a simple and cheap way for sensing information of the fiber sensor to access the wireless sensor network. An experiment was implemented to measure the strain and the corresponding root mean square deviation is about -5.7 με at 916 MHz and -3.8 με at 1713 MHz after wireless transmission.

OCDMA En/Decoders Employing Multiple

Based on the equivalent phase shift (EPS) technology, the optical code-division multiple access (OCDMA) en/decoders employing multiple pi-EPSs have been studied both numerically and experimentally, which demonstrate good en/decoding performances. It is also shown that the insertion of multiple pi-EPSs offers a new degree of freedom for OCDMA security, in which the multiple pi -EPSs decoder is completely unmatched with single pi-EPSs encoder even if they have the same code sequence.