高频调制大功率窄线宽分布反馈光纤激光器

研制了一种窄线宽光纤激光器.在有源相移光栅后加一段掺铒光纤,当用980 nm抽运光注入时,首先形成了分布反馈(DFB)光纤激光器,而残余抽运光将铒纤中铒离子从基态抽运到了激发态,对DFB激光实现了有效放大,实现了对残余抽运光的充分利用,节省了功耗、降低了成本;同时利用温控技术克服了DFB光纤激光器的温度敏感问题;将相移光栅黏贴于片状压电陶瓷(PZT)的表面实现了高频调制.实验研制的激光器的最高调制频率为2 kHz、输出功率为15.6 dBm,线宽为300 kHz. 关键词： 分布反馈光纤激光器 窄线宽 大功率 高频调制     

Single-frequency, single-polarization ytterbium-doped fiber laser by self-injection locking

We demonstrated a stable single-frequency, single-polarization operation of ytterbium-doped fiber laser. As a novel practical method to realize single-polarization operation of fiber distributed Bragg reflector (DBR)laser, we proposed self-injection locking (SIL) with an active fiber ring feedback cavity. The laser has high output power exceeding 15 mW, wavelength of 1053.20 nm, and side-mode suppression ratio greater than 60 dB. The SIL fiber laser shows the improvements in output power and side-mode suppression compared with the fiber DBR laser. No mode-hopping is observed within 2 hours.     

High-power Tm-doped fiber distributed-feedback laser at 1943 nm

We report on high-power operation of a fiber distributed-feedback (DFB) laser fabricated from Tm-doped photosensitive alumino-silicate fiber and in-band pumped by an Er/Yb fiber laser at 1565 nm. The fiber DFB laser yielded up to 875 mW of single-ended output at 1943 nm on two orthogonally polarized modes for 3.5 W of absorbed pump power. Further scaling of the DFB laser output power was achieved with the aid of a simple Tm-doped fiber amplifier stage spliced directly to the DFB fiber without the need of an optical isolator. The maximum output power from the DFB laser and fiber amplifier was >3 W for a combined absorbed pump power of 8.1 W. The influence of thermal loading, owing to quantum defect heating in the Tm-doped core, on the output power and longitudinal mode behavior is discussed, and the prospects for further improvement in performance are considered.     

Stable single frequency and single polarization DFB fiber lasers operated at 1053 nm

Stable single-frequency and single-polarization distributed-feedback (DFB) fiber laser was realized by giving a pressure on the phase shift region of the fiber grating. The output wavelength of the DFB fiber laser is 1053 nm. When the pump power of 980 nm laser diode is 100 and 254 mW, the output power can reach 8.3 and 37.1 mW and the polarization extinction ratio was 26 and 20 dB, respectively. After chopped by Acousto-optic modulator (0.3 Hz), the pulse peak value variance is 4.65%(peak to peak) and 1.098% (RMS) for 31 min.     

Single-frequency thulium-doped distributed-feedback fiber laser

We have successfully demonstrated a single-frequency distributed-feedback (DFB) thulium-doped silica fiber laser emitting at a wavelength of 1735 nm. The laser cavity is less than 5 cm long and is formed by intracore UV-written Bragg gratings with a phase shift. The laser is pumped at 790 nm from a Ti:sapphire laser and has a threshold pump power of 59 mW. The laser has a maximum output power of 1 mW in a single-frequency, single-polarization radiation mode and is tunable over a few nanometers. To the best of the authors' knowledge, this is the first report of a single-frequency DFB fiber laser that uses thulium as the amplifying medium. The lasing wavelength is the longest demonstrated with DFB fiber lasers and yet is among the shortest obtained for thulium-doped silica fiber lasers.     

Analysis on DFB laser diode with main and multiple side modes injection-locked

One distributed feedback (DFB) laser diode with main and multiple side modes injection-locked is proposed and demonstrated. DFB laser diode can be successfully injection-locked not only in the main mode but also in the side modes. The side mode suppression ratio (SMSR) value of each injection-locked mode is enhanced, thereby, it can be a promising candidate for the use of multiple optical sources. Our proposed scheme has the potential to be used as optical sources for radio-on-wavelength division multiplexing (WDM) transport systems to provide multiple services.     

Single-frequency Brillouin distributed feedback fiber laser

We demonstrate a single-frequency Brillouin distributed feedback laser (DFB). The DFB laser cavity was a 12.4 cm long fiber Bragg grating with a π-phase shift offset from the grating center. It exhibited a threshold of 30 mW and conversion efficiency from pump to Stokes wave as high as 27%. Higher-order Stokes waves were suppressed by more than 20 dB. The Stokes output of the laser could be obtained in either the forward or backward direction, simply by changing the orientation of the offset of the discrete phase shift with respect to the pump propagation direction. The DFB laser operated over a pump frequency range of 1.2 GHz, more than 60 times larger than the SBS gain bandwidth.     

Bidirectional radio-over-fiber systems with SSB modulation and wavelength reuse based on injection-locked semiconductor lasers

A 60-GHz bidirectional radio-over-fiber （RoF） system using two-carrier-injected distributed feedback （DFB） laser is proposed and demonstrated to realize optical single sideband （SSB） modulation for downlink.An injection-locked Fabry-P＇erot laser is also carried out to realize wavelength reuse in uplink.Transmission of 2.5 Gb/s on a 60-GHz carrier for downlink and 622-Mb/s baseband signal for uplink are both successfully demonstrated over 50-km single mode fiber without chromatic dispersion compensation.     

Experimental study on injection-locked Ti:sapphire lasers

An injection-locked Ti:sapphire laser is developed,with injection locking achieved using the Pound-DreverHall technique.By measuring the dependence of output power on the pump power with various Ti:sapphire laser parameters,we experimentally studied the influences of the ring cavity length,the focal length of the pump-laser mode-matching lens,and the output-coupler transmission on the threshold and slope efficiency.The dependence of the output power on the master laser power is also investigated.The present study provides a guideline for developing a Ti:sapphire laser with high slope efficiency and low threshold.     

Raman fiber distributed feedback lasers

We demonstrate fiber distributed feedback (DFB) lasers using Raman gain in two germanosilicate fibers. Our DFB cavities were 124 mm uniform fiber Bragg gratings with a π phase shift offset from the grating center. Our pump was at 1480 nm and the DFB lasers operated on a single longitudinal mode near 1584 nm. In a commercial Raman gain fiber, the maximum output power, linewidth, and threshold were 150 mW, 7.5 MHz, and 39 W, respectively. In a commercial highly nonlinear fiber, these figures improved to 350 mW, 4 MHz, and 4.3 W, respectively. In both lasers, more than 75% of pump power was transmitted, allowing for the possibility of substantial amplification in subsequent Raman gain fiber.     

窄线宽1064 nm光纤激光泵浦高效率中红外3.8μm MgO:PPLN光参量振荡器

采用放大1064?nm掺镱光纤激光器作为泵浦源,实现了中红外3.8?μm?MgO:PPLN光参量振荡(OPO)激光输出.在泵浦源中,采用分布式反馈激光器(DFB)作为种子源来实现光纤激光窄线宽的调制,实现线宽2.5?nm到0.1?nm的压缩,最大平均输出功率可达40?W.进一步对不同泵浦线宽条件下中红外3.8?μm?M...     

基于光纤Fabry-Perot滤波器的电光混合光学双稳态

提出了一种新型的电光混合光纤光学双稳装置,它由波长为1.55μm带尾纤的DFB半导体激光器、全光纤可调谐Fabry_Perot滤波器和电光反馈电路构成。实验中通过改变输入光强实现了光学双稳运转。讨论了该双稳器件在激光光强稳定器和光纤传感器方面的应用。     

Experimental study on kilowatt fiber laser in an all-fiber configuration

A high-power fiber laser in an all-fiber format is reported. The system consists of 36 pump ports, which use both counter and forward pump configuration. In the experiment, 1 008-W output power is obtained when 24 pump ports are used with a total pump power of 1477 W. The optical-to-optical conversion efficiency is 68% and the 3-dB bandwidth of laser output increases with output power. Presently, the output power is only limited by the pump source. It can be predicted that the laser power can be further scaled if more pump sources are utilized.     

激光线宽对单次通过PPMgO:LN晶体倍频效率的影响

通过单次穿过PPMgO:LN晶体产生了2.06 W的780 nm可调谐的连续倍频光. 采用1560 nm的分布反馈式(DFB)半导体激光器、光栅外腔半导体激光器(ECDL)和分布反馈式掺铒光纤激光器(DFB-EDFL)分别作为掺铒光纤放大器(EDFA)的注入光源, 所用的EDFA具有保持窄线宽的功能, 因此可以忽略它对基波线宽的展宽. 研究了激光线宽对单次通过PPMgO:LN 晶体的倍频效率的影响. 控制三台激光器各自注入EDFA的功率一致, 同时也保持EDFA 的输出功率. 在基波功率为12.42 W 时, 使用DFB半导体激光器注入EDFA时得到了1.36 W的780 nm倍频光输出, 转换效率为11.0%; 使用ECDL作为种子源时得到了1.78 W 的780 nm倍频光输出, 转换效率为14.3%; 使用DFB-EDFL作为种子源时得到了2.06 W的780 nm倍频光输出, 转换效率为16.6%. 测得三台种子激光器的线宽分别为1.2 MHz (DFB), 200 kHz (ECDL)和600 Hz (DFB-EDFL). 线宽越窄, 倍频效率越高, 实验结果与理论分析一致.     

303MHz高重复频率掺Er光纤飞秒激光器

高重复频率掺Er光纤飞秒激光器在光学频率梳、超高速光学采样等领域具有很重要的作用. 本文采用非线性偏振旋转锁模机理, 在掺Er光纤飞秒激光器中实现了重复频率为303 MHz的锁模脉冲输出. 通过优化腔内色散, 激光器腔内色散在零色散附近偏负值, 锁模后工作在展宽脉冲锁模状态. 在817 mW抽运功率下, 激光器在连续光状态下可以输出125 mW的平均功率, 在锁模状态下可以输出69 mW的平均功率, 脉冲宽度为90 fs. 当抽运功率处于700-817 mW时, 激光器可以实现自启动锁模. 激光器重复频率在5 h内的漂移量为30 Hz.     

2080 nm long-wavelength,high-power dissipative soliton resonance in a dumbbell-shaped thulium-doped fiber laser

We demonstrate a 2080 nm long-wavelength mode-locked thulium(Tm)-doped fiber laser operating in the dissipative soliton resonance(DSR) regime. The compact all-fiber dumbbell-shaped laser is simply constructed by a 50/50 fiber loop mirror(FLM), a 10/90 FLM, and a piece of large-gain Tm-doped double-clad fiber pumped by a 793 nm laser diode. The 10/90 FLM is not only used as an output mirror, but also acts as a periodical saturable absorber for initiating DSR mode locking. The stable DSR pulses are generated at the center wavelength as long as 2080.4 nm, and the pulse duration can be tunable from 780 to 3240 ps as the pump power is increased. The maximum average output power is 1.27 W, corresponding to a pulse energy of 290 nJ and a nearly constant peak power of 93 W. This is, to the best of our knowledge, the longest wavelength for DSR operation in a mode-locked fiber laser.     

Current-driven state-bistability and power-bistability in a DFB semiconductor laser subject to optical injection

In this paper, current-driven state-bistability and power-bistability in a distributed feedback (DFB) semiconductor laser (LD) subject to external optical injection have been investigated experimentally. The results show that, by sweeping the bias current of slave LD along different routes nearby the threshold, both the power-bistability and the state-bistability between locking and bimodal regime can be observed under the suitable injection power, but these bistable phenomena will disappear under much large injection power. Additionally, the dependence of the width of the state-bistablility loop on the injection power has been discussed.     

Narrow bandwidth operation of high-power broad-area diode laser using cascaded phase-conjugate injection locking

A broad-area laser is injection-locked by another broad-area laser that is also injection-locked by a single-mode diode laser. Two double-phase conjugate mirrors of photorefractive BaTaO₃ are used to couple the master laser beams to the first slave laser, and the first slave laser output to the second slave laser. One of the double-phase conjugate mirrors is built up with the beams from two broad-area lasers. Two slave lasers are oscillating in single longitudinal mode at 808.5 nm and the spectral width is the same as that of the master laser. Final single-mode output power from the second slave broad-area laser is 840 mW, which is limited by the power of the injection beam. This work verifies the possibility of the multi-stage cascaded injection locking of high-power diode lasers with phase-conjugate injection. Received: 18 November 1998 / Revised version: 29 January 1999 / Published online: 7 April 1999     

基于相位采样光栅的双波长光纤激光器

提出一种基于相位采样的分布反馈式双波长光纤激光器,在不同的空间化置同时引入相位和采样周期的突变.通过理论分析,这种结构能够实现谐振腔的分离,使不同波长的光波利用不同空间位置的增益介质,克服增益介质均匀加宽引起的模式竞争,实现双波长激射.采用准分子激光器和均匀相位模板,在掺铒光纤上制作波长差为0.46 nm的舣波长光纤激光器,能够实现舣波长激射.通过实验,对激光器输出功率和光栅强度的关系进行研究,表明输出功率和光栅强度成反比.     

Visible-to-near infrared standard source generation using acetylene (C2H2)-stabilized comb-injection-locked technique

An ultra-stable visible laser source (VLS) was generated by the second harmonic of a selectively injection-locked distributed feedback (DFB) laser from an optical frequency comb with acetylene-stabilized laser seeding. For the second-harmonic generation (SHG) of the injection-locked DFB laser, we used periodically poled lithium niobate (PPLN) crystal and generated the VLS at a region of 771 nm, which was discretely locked to a spacing of 25 GHz within the PPLN bandwidth (180 GHz). The frequency stability of this source was estimated to be 1.1 × 10^− 12 with an average time of 1 s.