共查询到20条相似文献,搜索用时 31 毫秒
1.
In this paper, we demonstrate the electrical control of the distributed feedback (DFB) organic semiconductor laser based on a holographic polymer dispersed liquid crystal (HPDLC) grating for the first time. The grating is fabricated on the top of the organic semiconductor film to act as an external feedback structure. Experimental results show that the lasing intensity can be decreased by increasing the external electric field, and the lasing wavelength exhibits a slight blue-shift of 1.4 nm during the modulation process, indicating a good stability. The modulated performances are attributed to the decreases in the refractive index modulation and average refractive index of the HPDLC grating respectively as a result of the field-induced liquid crystal reorientation. This study provides some new ideas for the improvement of DFB organic semiconductor laser to enable envisioned applications in laser displays and integrated photonic circuits. 相似文献
2.
In this letter, we describe a simple method to adjust the oscillation wavelength of distributed-feedback (DFB) lasers after the device fabrication without using any external active tuning. The method utilizes a permanent change of refractive index in the quantum well active layer induced by external laser beam irradiation. We have demonstrated 0.36 nm adjustment in a 1.55-/spl mu/m ridge waveguide DFB laser. 相似文献
3.
A 1.55 μm laser source with low chirp and high speed can be achieved when a single-mode DFB laser is modulated by an integrated quantum-confined Stark effect electroabsorptive modulator. The dynamic characteristics of such a device are simulated by a time domain, large signal dynamic model. The simulation demonstrates that the frequency chirp has two components: 1) changes of the refractive index induced by variation of the absorption coefficient during the modulation and 2) changes in the lasing frequency caused by changes in the effective residual facet reflection as the external modulator is switched on and off. Optimization by choice of the operating wavelength and coupling coefficient in the lasing section is discussed 相似文献
4.
为了利用悬空的周期可调光栅控制激光器的波长输出,采用了微机电系统技术中微驱动器与分布反馈激光器光栅相结合的结构,根据严格耦合波理论和介质平板波导理论,针对光通信的C波段,利用有限元软件COMSOL,建立了基于氮化镓的波长可调分布反馈激光器2维稳态模型。分析了1550nm处2维电场模式图以及激射波长线宽图,得到了激射波长与光栅周期的对应关系。结果表明,在光栅厚度、高度以及增益层厚度等结构参量一定的情况下,激射波长与光栅周期呈现与理论分析基本一致的似线性关系。该研究为该器件设计以及制备的后期工作开展提供了理论指导意义。 相似文献
5.
报道了一种基于液晶/聚合物光栅选频的高效率有机半导体激光器的制备方法。首先在一片玻璃基板上旋涂有机半导体荧光薄膜MEH-PPV作为增益介质,然后在其上通过光场中的定域光聚合制备液晶/聚合物光栅,形成分布式反馈(DFB)有机半导体激光器。激光出射阈值0.32μJ/pulse,斜率转化效率高达7.8%,呈现良好的s偏振特性。采集了激光束的光斑,轮廓清晰,呈现扇形结构。通过改变光栅周期,实现了53.4nm激光出射范围。本工作为新型有机激光器的制备提供了有益的指导和借鉴意义。 相似文献
6.
A new tunable single-longitudinal-mode laser structure is reported. This monolithic hybrid DFB/DBR laser can be electrically tuned over a 5 nm wavelength range. The tuning mechanism employs the depression in the refractive index with injected carrier density, and the tuning range is linked to the period of an internal diffraction grating. 相似文献
7.
Thermal annealing effect on an organic distributed feedback (DFB) laser excited from a semiconducting polymer gain layer, poly(2-methoxy-5-(2’-ethyl-hexyloxy)-p-phenyl-envinylene) (MEH-PPV), is reported. The morphology, absorption and photoluminescence (PL) spectral characteristics of the MEH-PPV film annealed at different temperatures were analyzed. The amplified spontaneous emission (ASE), the optical gain and loss coefficients were also investigated. The organic lasing behaviors including threshold, energy conversion efficiency and polarization state in a DFB laser device were studied. The results show that the optical properties of the organic semiconducting laser can be enhanced by thermal annealing effect. The single mode laser emission at 622.4 nm with lower lasing threshold 0.2 μJ/pulse and higher energy conversion efficiency 6.71% was achieved with thermal annealing at 120 °C. The thermal annealing treatment decreases laser threshold and increases laser energy conversion efficiency dramatically, which shows the potential in ultra-low cost organic semiconducting polymer DFB lasers. 相似文献
8.
Wenbin Huang Yonggang Liu Lifa Hu Quanquan Mu Zenghui Peng Chengliang Yang Li Xuan 《Organic Electronics》2013,14(9):2299-2305
We report on the fabrication and characterization of a second-order distributed feedback (DFB) polymer laser based on a holographic polymer dispersed liquid crystal (HPDLC) transmission grating. The fine organic grating is fabricated on top of the homogeneous conjugated polymer layer in a one-step process. The device shows surface-emitting, single mode laser emission with a threshold of 13.3 μJ/cm2, and the working characteristics merely degrade after 10 months of storage in ambient atmosphere. We further explain the dependence of threshold on pumping length, and demonstrate the small refractive index modulation of this all-organic grating is sufficient to maintain efficient DFB laser action. This simple working structure, combined with large processing area provided by the holographic polymerization technique, is extremely promising in realizing ultra-low cost plastic lasers. 相似文献
9.
本文介绍1.55μm波长可调谐DFB激光器的结构及特性。激光器腔长为250μm。隔离电阻约60Ω。在总电流恒定时,波长调谐范围超过15A(190GHz)。边模抑制比(SMSR)大于30dB。 相似文献
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11.
用液晶分子运动的动力学方程,求出了激光诱导向列相液晶分子重新取向的取向角、折射率改变、阈值场强和上升时间的近似表达式。讨论了它们随液晶材料参数、激光强度和激光在液晶中传播方向的变化,进行了数值计算。给出了激光能诱导向列相液晶分子重新取向的必备条件,得到向列相液晶的各向异性是其分子重新的取向的根本原因。 相似文献
12.
The maximum possible shift in emission wavelength of a quantum-well (QW) intermixed distributed-feedback (DFB) laser as a function of degree of intermixing is studied. In a recent experiment, the wavelength shift of a QW intermixed DFB laser is around 13% of the bandgap blue shift. Our study indicates that if a smaller grating period is used, the wavelength shift can be increased by four times to 50% of the bandgap blue shift, because it is not necessary to change the carrier density significantly in order to maintain a modal gain above lasing threshold. The maximum tuning range is found to be 20 nm, indicating that QW intermixing can be used to fabricate multiwavelength DFB laser arrays for wavelength-division-multiplexing communication systems 相似文献
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14.
Wavelength tuning in distributed-feedback (DFB) lasers using quantum-well intermixing is analyzed. A 0.42-nm tuning range is obtained when the bandgap is blue-shifted by 5.9 nm, and this value agrees well with the experimental value of 0.36 nm. The limitation of the tuning range is also discussed, and is because of the increase in carrier density that raises the gain above the threshold after intermixing. The dependence of wavelength shift on bandgap blueshift is not affected by the details of the intermixing process. A maximum tuning range of 3.5 nm is predicted, demonstrating that after device fabrication intermixing process can be used to adjust DFB lasers operating wavelengths to match the predefined wavelength channels of wavelength-division-multiplexing system 相似文献
15.
A theoretical study is made of the frequency pulling effect exerted on a distributed feedback (DFB) laser by an external amplitude modulator that is directly attached to it. The modulator consists of a piece of waveguide whose loss is modulated by means of an externally applied voltage. The modulator affects the laser due to residual reflections from its far end which appear as a variable effective reflectivity to the output end of the DFB laser. Modulation affects the magnitude as well as the phase of the effective reflection coefficient presented to the laser due to the coupling of the real and imaginary parts of the effective refractive index of the modulator waveguide. The tuning problem is formulated as an eigenvalue equation for the DFB laser in the presence of an externally attached lossy cavity 相似文献
16.
Multi-wavelength quantum well DFB laser array has been fabricated on an InP substrate by angling the active stripe at an oblique angle to the axis of the grating lines and coating a Pt/Ti thin-film heater to change the laser temperature. Owing to the oblique angle,four sin-gle-mode lasing wavelengths around 1.55μm were obtained simultaneously. By changing the working of the thin-film heater,the DFB laser can be tuned continuously beyond a range of 2.2nm with 3. 8nm/W of tuning efficiency while maintaining a side-mode suppression ratio (SMSR) more than 30dB. 相似文献
17.
A multiwavelength MQW DFB laser array with novel structure Is described. Oscillation wavelength and gain peak wavelength were simultaneously controlled on the same epitaxial wafer by using modulated grown thicknesses of selectively grown InGaAs/InGaAsP/InP MQW active waveguides. The laser array with constant-pitch built-in corrugation fabricated by a simple DFB laser process demonstrated 10.1 nm controllable range for lasing wavelength and 45 nm for gain peak wavelengths, with uniform lasing properties and narrow spectral linewidths. The technique is attractive for light sources used in WDM/FDM applications 相似文献
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19.
We propose utilization of quantum interference effects in quantum well structures to tune lasing wavelengths of mid-infrared distributed feedback lasers. The interference effects are generated via interaction of an intense laser field with an n-doped quantum well, causing coherent suppression or enhancement of refractive indexes of the conduction intersubband transitions. We show that these processes allow us to shift lasing wavelength to shorter or longer wavelengths by adjusting the intensity and frequency of the intense laser. This study is done for two types of lasers: 1) an electromagnetically induced distributed feedback intersubband laser formed by embedding a longitudinal corrugation of several periods of the quantum well structure within a waveguide structure and 2) a phase-shifted distributed feedback laser where the quantum well is inserted in the middle of an index grating, forming an active phase shift region. In the former the intense laser field is responsible for generation of optical feedback while shifting the coherently induced stop-band. In the latter, however, this field changes the optical length of the phase shift region, tuning the lasing mode within the stop-band. We show that the amount of the wavelength shift, which can reach 17 nm, is controlled by the intensity of the intense laser. The sign of the tuning process (red or blue shift), however, is decided by the frequency of this field, after proper choice of the corrugation periods. We investigate the optical feedback mechanisms in such coherently tunable lasers and discuss how they are related to an electromagnetically induced transparency process that happens in the conduction intersubband transitions. 相似文献
20.
Pengchang Yang Jinchuan Zhang Zenghui Gu Chuanwei Liu Yue Zhao Fengmin Cheng Shenqiang Zhai Ning Zhuo Junqi Liu Lijun Wang Shuman Liu Fengqi Liu 《半导体学报》2021,42(9):63-67
In this work,we demonstrated high-power quantum cascade laser (QCL) arrays lasing at λ ~ 5μm by employing an op-timized coupled-ridge waveguide (CRW) structure.Five-element QCL arrays were simulated and fabricated through a two-step etching method to extend the CRW structure to a mid-wave infrared regime.A lateral far-field with the main peak near a diffrac-tion-limited intensity curve of about 10° was observed by properly designing a geometric shape of the ridges and interspaces.By introducing a buried 2nd-order distributed feedback (DFB) grating,substrate emission with a radiation power above 1 W at 25 ℃ is achieved.Single longitudinal mode operation is obtained by changing the temperature of the heatsink with a good lin-ear wavelength tuning coefficient of-0.2 cm-1/K. 相似文献