The study of third harmonic demodulation in phase modulation optical heterodyne technique using optical resonator

With the technique of phase modulation optical heterodyne(PMOH), we detected the beat-frequency signal of the reflected wave from a F-P cavity. The frequency of the beat signal was three times of that of the modulation electric field, when the 3rd harmonic of the modulation electric field was used as the phase reference signal. The line shapes of the signal match those of the theoretical calculations, and the dispersion signal has good frequency-discrimination characteristic.     

The optimal design for weak optical feedback semiconductor laser with frequency modulation

In this paper the frequency modulation characteristics the semiconductor laserwith weak optical feedback are presented,considering both the frequency deviation and thespurious intensity modulation.The frequency modulation can be realized without spurious in-tensity modulation under proper feedback conditions.There is an optimal feedback intensity tomaximize the frequency deviation.     

A novel modulation and direct detection scheme of optical phase shift keying

This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the     

Piezoelectric film electro-deposition for optical fiber sensor with ZnO coating

The piezoelectric film electro-deposition for optical fiber sensor with ZnO coating is studied.The zinc oxide plating film is made on the copper surface directly by cathodic electro-deposition in the Zn(NO_3)_2 single salt aqueous solution systems.The influences of main experimental conditions on the properties of ZnO thin film in the electro-deposition processes are analyzed and a stable,practical and economic technique is obtained.     

Compensation for the self-steepening effects inoptical fiber communication system usingmidway optical phase conjugation

Effects of self-steepening (SS) of chirped Gaussian pulses on optical fiber communication system using midway optical phase conjugation (OPC) are analyzed. Dynamic evolution of the ultrashort pulses is simulated numerically. It is found that OPC cannot compensate for pulse waveform distortion due to SS. The initial chirp of pulses and dispersion can counteract SS and improve the compensation performance for the distortion.     

A hybrid strategy for cryptanalysis of optical encryption based on double-random phase–amplitude encoding

A hybrid two-step attack scheme that combines the chosen-plaintext attack (CPA) and the known-plaintext attack (KPA) algorithms is proposed to acquire the secret keys of the optical cryptosystem based on double-random phase–amplitude encoding (DRPAE) technique. By implementing our presented attack, an opponent can obtain not only the estimated solutions of the two random phase keys but also the accurate solution of the amplitude modulator (AM), which is introduced to the encryption process and regarded as an additional key to enhance the security level of the DRPAE-based cryptosystem. The validity and effectiveness of this attack strategy is analyzed theoretically and then verified by computer simulations.     

Effect of higher order non-linearity in frequency variation of self-phase modulation in optical fiber communication

In optical soliton propagation through a single mode optical fiber, it is established that self-phase modulation is maintained by the third order non-linearity of the silica-based glass material of the fiber. In this paper we show that the fifth order non-linearity has also some contribution in frequency variation of self-phase modulation.     

Flat amplitude multiwavelength Brillouin–Raman random fiber laser with a half-open cavity

In this paper, we experimentally demonstrate a novel configuration of multiwavelength Brillouin–Raman random fiber laser (MBRRFL) utilizing a half-open cavity. The laser resonator is formed by fiber loop mirror at the Brillouin pump (BP) side and random distributed Rayleigh backscattering in a 10 km dispersion compensating fiber. As a result, we are able to obtain a flat amplitude bandwidth of 16.8 nm from 1,550.0 to 1,566.8 nm built-in 210 uniform Brillouin Stokes lines with 0.08 nm spacing and an average OSNR of 13.5 dB. We also studied the influence of BP power and wavelength on the MBRRFL’s performance. Furthermore, comparing with the open cavity configuration, the discrepancies in power level and linewidth between neighboring channels are overcome by using the half-open cavity.     

Control of polarization signal distortion by frequency domain phase conjugation in optical fiber systems

Optical frequency domain phase conjugation(FDPC) is based on phase conjuga-tion of spectrum of an input signal.It is equivalent to the phase conjugation and the time reversal of the temporal envelope of an input signal.The use of FDPC to con-trol polarization signal distortion in birefringent optical fiber systems is proposed.Evolution of polarization signals in the system using midway FDPC is analyzed theoretically and simulated numerically.It is shown that the distortion of polariza-tion signals can be controlled effectively by FDPC.The impairments due to disper-sion and nonlinear effects can be suppressed simultaneously.     

The characters of dense dispersion managed soliton in optical fiber transmission systems

The properties of ultra-short dense dispersion-managed soliton (DBMS) in optical fiber links are investigated. They show some excellent characters, such as, reducing pulse's breathing extent greatly, facing fewer mutual interactions and tolerating larger local dispersion. In general, DBMS is more stable than a conventional dispersion-managed soliton in high-capacity systems. Excessively dense dispersion compensation is more suitable for systems with weak nonlinear effect.     

PZT相位调制器温度漂移的控制

在光纤陀螺中,ＰＺＴ相位谳制器受温度变化影响会导致陀螺输出信号漂移。本文就这个问题提出一种解决方案,并通过实验进行验证。     

压电式光纤相位调制器相移系数测试

介绍了压电式光纤相位调制器的相移系数理论公式,提出了基于杨氏双缝干涉原理的相移系数测量方法。对测量方法的可行性进行分析,通过实验对测量方法进行了验证。实际研制了一个基于压电陶瓷环的光纤相位调制器件,实验测得的相移系数与理论分析结果基本一致。利用研制的压电式光纤相位调制器实现了两路准直光束之间的相位锁定,在远场实现了相干合成,干涉条纹可见度从3%提升至43%。     

压电式光纤相位调制器相移系数测试

介绍了压电式光纤相位调制器的相移系数理论公式,提出了基于杨氏双缝干涉原理的相移系数测量方法。对测量方法的可行性进行分析,通过实验对测量方法进行了验证。实际研制了一个基于压电陶瓷环的光纤相位调制器件,实验测得的相移系数与理论分析结果基本一致。利用研制的压电式光纤相位调制器实现了两路准直光束之间的相位锁定,在远场实现了相干合成,干涉条纹可见度从3%提升至43%。     

Multiplexing and demodulation of fiber optic-based interferometric sensors using an integrated-optic amplitude /phase modulator

An integrated-optic amplitude and phase modulator is used in a network of interferometric sensors to create both a phase carrier and the pulses for multiplexing using time division. A time sampling technique is successfully used to account for the optical crosstalk in TDM processing and a very high frequency phase carrier is demonstrated.     

Wideband optical phase modulator half-wave voltage measurement technique based on phase modulation optical link

We measured the half-wave voltage V_π of LiNbO₃ phase modulators in the broadband frequency range by analyzing the gain of phase modulation interference demodulation optical link. This is a new high practical value measurement method for half-wave voltage of LiNbO₃ phase modulators in wideband frequency range, and can accurately predict the nonlinear frequency characteristics of phase modulation optical link.     

All-fiber optical modulator based on no-core fiber and magnetic fluid as cladding

An all-fiber optical modulator,which is composed of a piece of no-core fiber spliced between two sections of singlemode fibers and uses magnetic fluid(MF)as the cladding of the no-core fiber section,is proposed and investigated experimentally.Due to the tunable refractive index and absorption coefficient of MF,the output intensity can be modulated by controlling an applied magnetic field.The dependences of the modulator’s temporal response on the working wavelength,the magnetic field strength(H),and the MF’s concentration are investigated experimentally.The results are explained qualitatively by the dynamic response process of MF under the action of a magnetic field.The findings are helpful for optimizing this kind of modulator.     

High-resolution spectroscopy based on optical phase modulator and optical frequency comb

A phase modulation of an optical frequency comb has been applied to measure a fine spectrum in the 1.5 μm wavelength range by the optical heterodyne-detection method. The measurement frequency range covered 25 GHz, which satisfies the frequency interval of the optical frequency comb, with a spectral resolution of 1 MHz.     

采用PZT动态调制的光纤光栅应变力测量技术

提出了一种新型PZT的动态调制光纤光栅应变力测量技术。把光谱仪对峰值波长移动的测量改变为示波器对峰值光功率时间间隔的测量 ,并对这种技术进行了理论分析和实验研究。用交变电压调制固定在光纤光栅上的PZT ,同时对施加在光栅上的应力进行测量。实践证明 ,测光脉冲时间间隔法与光谱峰值移动法的测量结果相同 ,而且两者与理论计算结果相符     

Microwave photonic filter with negative coefficients based on counter-phase modulation using a single electro-optic phase modulator

A simple photonic approach is proposed for the implementation of a reconfigurable multi-tap microwave filter with negative coefficients. In this scheme, a dual-optical-input intensity modulation module which can perform counter-phase modulation is constructed using a single electro-optic phase modulator. Two inter-complementary microwave signals are experimentally obtained for verification of the function of counter-phase modulation. A reconfigurable four-tap microwave filter with two negative coefficients is implemented by experiment.     

Electrically ultra-fast tunable optical filter employing HiBi fiber and phase modulator

An electrically tunable optical filter with ultra-fast tuning time of a few picoseconds is proposed and demonstrated. The filter consists of a phase modulator with HiBi pigtails sandwiched between two polarizers. Tuning of 6.62 nm for a 16.06 nm FSR filter is obtained with an applied voltage of 0.9 V. Tuning speed at 10 Gb/s and risetime of 40 ps is demonstrated with a frequency shift keying modulation experimental setup. Faster tuning speed is potential since the scheme is based on the electro-optic effect of the LiNO₃ crystal with sub-picosecond response time.