Xuxing Chen

Multiwavelength fiber laser based on the utilization of a phase-shifted phase-only sampled fiber Bragg grating.

A semiconductor-optical-amplifier-based fiber laser incorporating with a phase-shifted phase-only sampled fiber Bragg grating (FBG) is proposed and experimentally demonstrated. Thanks to the intrinsic property of the phase-shifted phase-only sampled FBG, the proposed approach has an unique advantage, enabling one to tune and switch all the wavelength lasing simultaneously. The obtained fiber laser has a stable output with more than 30 wavelengths lasing. The 3 dB linewidth is approximately 13 pm, the signal-to-noise ratio is larger than 50 dB, and the nonuniformity of the output is smaller than 7.4 dB.

Phase Shifts Induced by the Piezoelectric Transducers Attached to a Linearly Chirped Fiber Bragg Grating

A simple method enabling to generate a stable and controllable phase shift in a linearly chirped fiber Bragg grating (FBG) is theoretically and experimentally demonstrated, which is based on the utilization of the mini-size piezoelectric transducers (PZTs). The magnitude of the induced phase shift can easily be controlled by adjusting the voltage applied on the individual PZT. With this method, a narrow bandpass filter with 3-dB band width of 0.085 nm is obtained. Based on this kind of filter, an Erbium-doped fiber ring laser is also demonstrated, and both switchable and stable single-longitudinal-mode (SLM) laser emission is successfully realized.

Advanced design of the ultrahigh-channel-count fiber Bragg grating based on the double sampling method

A double sampling method enabling to have excellent channel uniformity and high in-band energy efficiency is firstly proposed for the design of an ultrahigh-channel-count fiber Bragg grating (FBG), which is based on the simultaneously utilization of an amplitude-assisted phase sampling (AAPS) function and a phase-only sampling (POS) function. As examples, two typical 10-dB FBGs with a length of 12 cm, dispersion of - 1360 ps/nm, channel spacing of 0.8 nm, and a consecutive 135- and 405- channels are numerically designed. The maximum index-modulations required are about 0.8x10(-3), and 1.3x10(-3), respectively. Compared with the proposed method, the other two kinds of double sampling schemes by utilizing either the double AAPS (i.e., AAPS+AAPS) or the double POS (i.e., POS+POS) have also been introduced for the design of the multichannel FBGs. Fabrication tolerances to the designed 135-channel FBG obtained with the AAPS plus POS method are numerically investigated.

Phase-shift induced in a high-channel-count fiber Bragg grating and its application to multiwavelength fiber ring laser

A multichannel filter formed by the piezoelectric transducer (PZT)-induced phase shift in a phase-only sampled fiber Bragg grating (FBG) is experimentally demonstrated. The PZT-induced phase shift is stable and the magnitude of the induced phase shift is controllable. As an important application of this multichannel filter, a semiconductor optical amplifier (SOA)-based multiwavelength fiber ring laser is successfully demonstrated.

Simultaneous dispersion and dispersion-slope compensator based on a doubly sampled ultrahigh-channel-count fiber Bragg grating

A simultaneous dispersion and dispersion-slope compensator based on a doubly sampled fiber Bragg grating (FBG) with 153 channels has been demonstrated, which is obtained by simultaneously chirping the period of the seed grating and the periods of the two sampling functions. These two sampling functions are optimized with the simulated annealing algorithm and the Gerchberg-Saxton iterative method. Moreover, the spectral inclination (in reflection) inherently due to the different magnitudes of the channel dispersion has been successfully equalized.

Simultaneous Optical Pulse Multiplication and Shaping Based on the Amplitude-Assisted Phase-Only Filter Utilizing a Fiber Bragg Grating

A novel all-optical simultaneous pulse multiplication and shaping approach is proposed, which is based on the simultaneous utilization of two amplitude-assisted phase-only spectral filters realizable by using a short fiber Bragg grating. This proposed method enables to create a high-repetition-rate rectangular pulse train with both an ideal rectangular envelop and a high energy efficiency. As a particular example, a repetition rate of 90 GHz rectangular pulse train is numerically demonstrated from an initial 10 GHz Gaussian pulse train.

High Channel-Count Ultra-Narrow Comb-Filter Based on a Triply Sampled Fiber Bragg Grating

Based on a sampled fiber Bragg grating (FBG) with simultaneous utilization of two amplitude-assisted phase sampling functions and a phase-only sampling (POS) function, a novel comb filter that has a high channel count and an excellent channel uniformity is first proposed. With the proposed method, an ultra-narrow FBG-based filter with consecutive 1377 channels, a channel bandwidth of 1.5 GHz, and a channel spacing of 25 GHz is theoretically demonstrated.

Energy-Efficient Optical Pulse Multiplication and Shaping Based on a Triply Sampled Filter Utilizing a Fiber Bragg Grating

An efficient method for simultaneous optical pulse multiplication and shaping is first proposed that is based on a triply sampled spectral filter utilizing a fiber Bragg grating. The proposed method enables efficient generation of an optical pulse train with a large multiplication factor and an arbitrary intensity profile. As examples, pulse trains with a repetition rate of 225 GHz and either a flat-top or triangular pulse waveform are numerically demonstrated, generated from a 1-GHz transform-limited Gaussian pulse train.

Energy-efficient optical pulse multiplication and shaping based on triply-sampled spectral filter utilizing fiber Bragg grating

A novel all-optical simultaneous pulse multiplication and shaping approach is proposed, which is based on a triply sampled spectral filter utilizing fiber Bragg grating. This proposed method enables one to create a pulse train efficiently with both a high multiplication factor and arbitrary pulse profile. As an example, pulse train with a repetition rate of 225-GHz and flat-top intensity profile is numerically demonstrated, which is generated from 1-GHz transform-limited Gaussian pulse train with pulse width of 0.4 ps.

Enhanced slow light in a phase-shifted multichannel fiber Bragg grating assisted by stimulated Brillouin scattering

Slow light is theoretically and experimentally demonstrated in a phase-shifted multichannel fiber Bragg grating (FBG) which has the ability not only to produce the slow-lights in multiple channels simultaneously but also to make the delay time tunable by changing the magnitude of the inserted phase shift. Phase shift is introduced into a phase-only sampled 51-channel FBG by utilization of a small piezoelectric transducer (PZT). On the other hand, the group delay of each channel can be further enhanced by incorporating stimulated Brillouin scattering (SBS).