Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers

Tunable distributed Bragg reflector (DBR) lasers are essential components for future optical fiber communi- cation systems[1]. A tunable laser can replace a large number of distributed feedback (DFB) lasers as sparing source in wavelength division multiplexing (WDM) sys- tems. Moreover they allow flexible switching and routing for distributed data in future network[2]. There are several methods for integrating gain sec- tion with DBR section, such as butt-joint method, bundle method, and …     

Offset quantum-well method for tunable distributed Bragg reflector lasers and electro-absorption modulated distributed feedback lasers

A two-section offset quantum-well structure tunable laser with a tuning range of 7 nm was fabricated using offset quantum-well method. The distributed Bragg reflector (DBR) was realized just by selectively wet etching the multiquantum-well (MQW) layer above the quaternary lower waveguide. A threshold current of 32 mA and an output power of 9 mW at 100 mA were achieved. Furthermore, with this offset structure method, a distributed feedback (DFB) laser was integrated with an electro-absorption modulator (EAM),which was capable of producing 20 dB of optical extinction.     

GaAs distributed Bragg reflector lasers

An equivalent cavity approach is used to derive the oscillation condition of a distributed Bragg reflector laser. The oscillation frequencies and thresholds are determined graphically. The effect of lossy reflectors is discussed. Several advantages and potential applications of distributed Bragg reflector structures are pointed out. Experimental results on optically pumped GaAs lasers are presented.     

Analysis of sensitivity and low-frequency intensity noise characteristics of Bragg reflector lasers induced by reflected light

An analysis of the sensitivity and low-frequency intensity noise characteristics of Bragg reflector lasers is given. It is found that Bragg reflector lasers have increased sensitivity to reflected light for low grating coupling strength (l) and is similar to that of Fabry-Perot lasers except for highl values. Also, the intensity noise can be reduced by operating the device at high injection level.     

Solgel grating waveguides for distributed Bragg reflector lasers

Solgel grating waveguides and their application to the fabrication of external-cavity distributed Bragg reflector (DBR) lasers are demonstrated. A new composition of aluminosilicate material is developed for the fabrication of single-mode waveguides and Bragg reflectors. An average loss of <0.2 dB/cm is measured in the single-mode waveguides at 1550 nm. The reflectors show filtering greater than 97% near 1530 nm, with a bandwidth of ~0.6 nm . The Bragg reflectors are used as feedback resonators for DBR lasers. Single-mode lasing with a sidemode suppression of better than 25 dB is demonstrated.     

Transmission matrix modelling of sampled-grating distributed Bragg reflector lasers

The transmission matrix model (TMM) has been used to simulate the tuning behaviour of a sampled-grating distributed Bragg reflector (SG-DBR) laser for the first time, to the best of our knowledge. The model is able to describe all details of the spontaneous emission spectrum below threshold and yields results in good qualitative agreement with experiment.     

Improving the modulation efficiency of high-power distributed Bragg reflector tapered diode lasers

Different measures to improve the modulation efficiency of a distributed Bragg reflector tapered diode laser emitting at 1060 nm were investigated. Due to the 6-mm long cavity, the device reached an output power of 10 W with a nearly diffraction-limited beam quality. The input currents to the ridge-waveguide (RW) and tapered gain-region sections can be independently controlled. This allows a low-current modulation of the optical output power in the Watt range. Under optimized quasi-static conditions the power could be modulated between 0.2 and 3.1 W (4.8 W) by a variation of the RW current between 0 and 50 mA (350 mA). Due to the integrated 6th order surface Bragg grating the emission wavelength remains within the spectral range of 80 pm.     

Intensity noise reduction in a multiwavelength distributed Bragg reflector fiber laser

Noise reduction in a multiwavelength distributed Bragg reflector fiber laser was demonstrated. A 20 dB reduction of in-phase intensity noise was achieved by using negative feedback to modulate the drive current of the laser pump diode. Strategies for reducing antiphase noise components are discussed.     

Spatial and spectral filtering of tapered lasers by using tapered distributed Bragg reflector grating

A 1040 nm tapered laser with tapered distributed Bragg reflector (DBR) grating is designed and fabricated. By designing the grating with tapered layout, the tapered DBR grating exhibits the scattering effect on side backward-traveling waves, thus achieving additional suppression of parasitic oscillation. Under the suppression of parasitic oscillation, the spatial and spectral characteristics of the tapered laser are improved. The experimental results show that a near-Gaussian far-field distribution and a kink-free P-I characteristics are achieved, and a single peak emission with a wavelength of 1046.84 nm and a linewidth of 56 pm is obtained.     

Pump-to-Stokes transfer of relative intensity noise in Brillouin fiber ring lasers

We have experimentally investigated pump-to-Stokes intensity noise transfer in both the frequency domain and the time domain in all-fiber single-frequency Brillouin ring lasers. In the high-frequency region (>1MHz), the pump-to-Stokes noise transfer function can be much smaller than unity, indicating that the Brillouin fiber lasers act as an efficient low-pass filter. The maximum noise reduction of 40-60 dB was observed at antiresonant frequencies that are multiples of half the cavity free spectral range. This is the first experimental demonstration, to the authors' knowledge, of intensity noise reduction in Brillouin fiber lasers.     

Demonstration of a widely tunable digital supermode distributed Bragg reflector laser as a versatile source for near-infrared spectroscopy

In this paper we report the characterization of a novel, widely tunable, diode laser source operating over the full telecom L-band (1563–1613 nm), namely the digital supermode distributed Bragg reflector (DS-DBR) laser, and its application to multi-wavelength gas sensing via absorption strategies. The spectroscopic performance of the laser has been assessed by investigating the ro-vibrational spectrum of CO₂, and wavelength modulation spectroscopy was accomplished for proof-of-principle sensitive measurements in discrete spectral regions.     

Tunable fiber Bragg gratings for application in tunable fiber lasers

The resonance wavelength of the fiber Bragg gratings (FBGs) is tuned using two methods. Tunable FBGs are used as the selecting elements in the cavities of tunable lasers. An ytterbium-doped fiber laser with a wavelength tuning range of 1063–1108 nm and an output power of 6 W, a Raman fiber laser with a wavelength tuning range of 1252–1303 nm and an output power of 3 W, and an erbium-doped fiber laser with a wavelength tuning range of 1530–1580 nm are realized, and their characteristics are studied.     

Experimental investigation of relative intensity noise in Brillouin fiber ring lasers for microwave photonics applications

Intensity noise characteristics of a single-mode Brillouin fiber ring laser are experimentally analyzed from 100 kHz up to 18 GHz. The Stokes wave is shown to be shot-noise limited to -155 dB/Hz for a 1 mA detected photocurrent over the whole spectral range 100 MHz-18 GHz. The pump-to-Stokes noise filtering efficiency is evaluated by artificially increasing the pump intensity noise. It evidences that a shot-noise-limited Brillouin laser could be realized by using a narrow-linewidth semiconductor laser pump, for stringent microwave photonics applications.     

Realization of a distributed Bragg reflector for propagating guided matter waves

We report on the experimental study of a Bragg reflector for guided, propagating Bose-Einstein condensates. A one-dimensional attractive optical lattice of finite length created by red-detuned laser beams selectively reflects some velocity components of the incident matter wave packet. We find quantitative agreement between the experimental data and one-dimensional numerical simulations and show that the Gaussian envelope of the optical lattice has a major influence on the properties of the reflector. In particular, it gives rise to multiple reflections of the wave packet between two symmetric locations where Bragg reflection occurs. Our results are a further step towards integrated atom-optics setups for quasi-cw matter waves.     

Characteristics of the distributed Bragg reflector fiber laser sensor for lateral force measurement

Characteristics of the distributed Bragg reflector fiber laser sensor for lateral force measurement are investigated. The distributed Bragg reflector fiber laser operates in dual-polarization modes and converts the lateral force into a corresponding shift in the beat frequency generated by the fiber laser. The sensitivity dependence on the angle between the force direction and the polarization axis orientation of the fiber is investigated theoretically and experimentally. The impact of the force action location and force length on the sensor response is also discussed. Good agreement between the theoretical data and the experimental results was obtained. A maximal sensitivity magnitude of ∼10 GHz/(N/mm) is recorded.     

基于分布式布拉格反射器结构的空间三结砷化镓太阳能电池抗辐照研究

根据电子辐照条件下的常规三结砷化镓太阳能电池光谱响应以及电池电流的损伤特征, 确定电池衰减的物理机理: 中电池在电子辐照后形成的辐照损伤缺陷, 使得基区少子扩散长度被大幅缩短, 影响了光生载流子的收集. 针对中电池衰减的物理机理, 设计不同的基区厚度, 验证辐照后扩散长度缩短至1.5 μm左右. 为提升中电池抗辐照性能, 消除辐照后扩散长度缩减带来的影响, 对中电池外延结构进行设计, 将中电池基区减薄至1.5 μm, 并在其下方嵌入分布式布拉格反射器, 对特定波段光反射进行二次吸收, 弥补中电池减薄的影响. 通过TFCalc光学模系设计软件模拟出的中心波长为850 nm, 15对Al_0.9Ga_0.1As/Al_0.1Ga_0.9As的分布式布拉格反射器, 实际测试最高反射率大于97%, 高反带宽94 nm, 能够满足设计要求. 此基础上进行了新结构电池的外延生长与辐照测试对比. 实验结果表明: 新结构太阳能电池辐照后短路电流衰减比原结构降低了50%, 效率的剩余因子提升2.3%.     

波长可调谐取样光纤光栅激光器的输出特性研究

建立了具有两个取样周期略有不同的取样光纤光栅反射镜的Vernier波长调谐机制的光纤分布布拉格反射式激光器的数值仿真模型,对激光器的输出特性进行了分析. 研究了激光器输出特性随着激光器前后光栅反射镜波长以及前后光栅反射镜反射率的变化关系. 提出了对两取样光栅反射率的优化配置方案,可以使输出激光的边模抑制比有所提高;同时对波长调节方式也进行了探讨;进行了实验研究. 关键词： 取样光纤光栅 光纤激光器 波长可调谐激光器     

Spontaneous emission coupling factors in planar micro-cavity lasers with distributed Bragg reflectors

In this article, a considerable value of spontaneous emission factor is estimated based on the spontaneous emission radiation patterns in micro-cavity lasers. After the spontaneous emission for a dipole in the micro-cavity is studied, the confinements of vacuum fields and electrons are considered together for a quantum well in the micro-cavity laser. The TE mode and TM mode spontaneous emission spectra are presented for a single quantum well embedded in a planar micro-cavity laser at 300 K. The results show that the TE mode spontaneous emission spectrum is enhanced, whereas the TM mode spontaneous emission is suppressed greatly. The maximum values obtained for the spontaneous emission coupling factors are 0.2 and 0.0055 for a dipole and a quantum well planar micro-cavity laser with distributed Bragg reflectors, respectively.     

The simulation of self-mixing interference effects in three-section DBR lasers

The self-mixing interference in three-section distributed Bragg reflector (DBR) lasers is analyzed based on the model of F-P cavity and coupling wave equation. The oscillating frequency and threshold variation are deduced. The influence of internal and external parameters on the output intensity and the inclination degree of waveform are discussed in simulation.