Local density of states in photonic crystal cavity

Local radiative density of optical states (LDOS) offers a tool to control the radiative rate of spontaneous emission from molecules,atoms,and quantum dots,which is proportional to LDOS.This paper prese...     

一维液晶缺陷光子晶体温度传感器的研究

将向列相液晶作为缺陷层引入一维光子晶体中,利用液晶折射率对温度变化敏感特性,设计了一维液晶缺陷光子晶体温度传感器。用传输矩阵法研究了传感器的温度特性,并用Matlab编程进行了模拟计算。结果表明,当温度升高时,液晶排列沿平行介质表面的传感器,缺陷峰波长向长波长方向漂移,缺陷模透射峰的宽度减小;而液晶排列沿介质表面法向的传感器,缺陷峰波长则向短波长方向漂移,缺陷模透射峰的宽度增大;传感器的温度灵敏度大于普通材料缺陷的光子晶体,与液晶材料和温度有关,温度接近液晶相变点而增大迅速;传感器缺陷峰波长的漂移与温度成非线性关系。设计了温度传感器探头结构和实验测量系统,测量结果与理论计算值符合。     

一种光子晶体开放腔的特性研究

为了研究光子晶体开放腔特性,采用平面波展开法和时域有限差分法对顶角为30°楔角的光子晶体和空气槽交替组成的新型光子晶体开放腔进行了研究.研究发现,这种结构的光子晶体开放腔在两个归一化频率范围(0.3006～0.35,0.6755～0.6851)内具有负折射特性,并且在负折射频率范围内可形成一个零光程的闭合回路;光子晶体...     

超低阈值横向腔光子晶体面发射激光器

首次在无DBR结构的商业外延波导晶片上实现了电泵横向腔光子晶体面发射激光器(LC-PCSEL)。深孔刻蚀技术使光子晶体深达2.6μm,穿透有源区,对有源区的模式直接调制。通过较小区域的光子晶体与FP腔的融合集成,利用带边模式Γ2-1的横向振荡垂直输出特性,室温下获得了1553.8 nm的面发射激光,线宽0.4 nm。超低阈值电流密度为667 A/cm2,纵向和横向的远场发散角分别为7.5°和5.5°。LC-PCSEL的设计为电注入面发射激光器的研制提供了新的思路,为该类激光器的批量生产提供了可能。     

Symmetry relations of two-dimensional photonic crystal cavity modes

Degeneracy of resonant modes in two-dimensional (2-D) photonic crystal cavities are investigated using the symmetry relations. The 2-D photonic crystal cavity tends to have either a pair of doubly degenerate modes or nondegenerate modes. We derive simple relations between degenerate modes without using a rigorous group theory. These relations are useful for classifying the resonant modes into degenerate pairs and nondegenerate ones.     

Micro-fluidic photonic crystal vertical cavity surface emitting laser

The first monolithic micro-fluidic photonic crystal vertical cavity surface emitting laser (VCSEL), wherein the horizontal and vertical micro-fluidic channels lie within the VCSEL, is reported. The micro-fluidic photonic crystal VCSEL is created with two principal steps after fabrication of the VCSEL. The first step is integrating the two-dimensional photonic crystal with the VCSEL structure. The photonic crystal creates singlemode operation, and acts as the vertical micro-channels. After creating the photonic crystal pattern in the VCSEL, the oxide layer is selectively wet etched to form the horizontal channel. Preliminary results obtained from the introduction of fluid into the micro-channels are presented.     

Coupled-defect photonic crystal vertical cavity surface emitting lasers

Photonic crystal patterns containing two defects were fabricated within a large gain area in vertical cavity surface emitting lasers. By designing effective refractive index changes in the region between the defects through cavity shifts caused by photonic crystals, it was possible to coherently couple laser light output from the defects. This enables a novel way to fabricate coherently coupled laser arrays.     

Room temperature photonic crystal defect lasers at near-infraredwavelengths in InGaAsP

Room temperature lasing from optically pumped single defects in a two-dimensional (2-D) photonic bandgap (PBG) crystal is demonstrated. The high-Q optical microcavities are formed by etching a triangular array of air holes into a half-wavelength thick multiquantum-well waveguide. Defects in the 2-D photonic crystal are used to support highly localized optical modes with volumes ranging from 2 to 3 (λ/2n)³. Lithographic tuning of the air hole radius and the lattice spacing are used to match the cavity wavelength to the quantum-well gain peak, as well as to increase the cavity Q. The defect lasers were pumped with 10-30 ns pulses of 0.4-1% duty cycle. The threshold pump power was 1.5 mW (≈500 μW absorbed)     

Characteristics of a photonic crystal defect waveguide-coupled quantum-dot photodiode

We have investigated the characteristics of an In/sub 0.4/Ga/sub 0.6/As self-organized quantum-dot (QD) resonant-cavity photodiode. The QD epitaxy and the design of the two-dimensional photonic crystal cavity are tailored for 1.3-/spl mu/m wavelength operation. The input excitation to the photodiode is provided with an in-plane defect waveguide designed with the same photonic crystal. The measured spectral photocurrent characteristics reflect mode coupling between the waveguide and detector and the resonant cavity effect due to total internal reflection and photonic bandgap confinement. The photocurrent response is explained with a model involving the circulating fields in the cavity. The characteristics are also dependent of cavity size. Enhancement and narrowing (/spl sim/ 10 nm) of the photoresponse at /spl lambda//spl sim/1.3 /spl mu/m are observed. A spectral dip, of /spl sim/ 10-nm width, also observed at 1.3 /spl mu/m is possibly due to the anticrossing mechanism, uniquely present in photonic crystal waveguides.     

一维缺陷光子晶体多个禁带中的窄带缺陷模

用特征矩阵法研究了一维缺陷光子晶体的透射谱。结果发现:在一维缺陷光子晶体的透射谱中的多个禁带内都有窄带缺陷模,窄带缺陷模的波长越大,其宽度越大;当入射角增大后,波长越长的窄带缺陷模的强度变化越小,位置向短波方向移动越多,且S偏振光与P偏振光的窄带缺陷模的分离越大;增大一维缺陷光子晶体中周期性介质的厚度,窄带缺陷模的波长和移动的范围都增大。本研究对一维缺陷光子晶体的窄带缺陷模的选择使用具有重要意义。     

Characteristic analysis of photonic crystal resonant cavity in the terahertz region

In this letter, a kind of two-dimensional photonic crystal structure applicable to THz devices is designed, and how to form a microcavity in this structure is discussed. The primary properties of the resonant cavity are analyzed, in which plane wave expansion method is used to make the calculation and the simulation. We＇ve studied the variation of the bandgap structure and resonant frequency in THz region by changing the parameters, such as lattice constant, dielectric constant contrast and filling factor. The research results provided theoretical support for manufacturing the THz devices and the application of THz system.     

点缺陷半径变化对光子晶体直接耦合结构THz波调制器性能的影响

点缺陷构成的微腔对THz波调制器的性能起着决定性的作用,而在实际制作加工过程中,由于工艺的原因,光子晶体的结构参量会产生偏差,难以制备出孔径毫无偏差的光子晶体,且介质柱的放置位置不能达到完全精确,因此光子晶体器件的性能也因此会受到一定程度的影响。文中重点讨论了点缺陷介质柱的半径变化对直接耦合结构的THz波调制器性能的影响,为光子晶体调制器的实际制作和相应的误差分析提供了理论帮助。     

InP-based short cavity lasers with 2D photonic crystal mirror

The authors have successfully fabricated in-plane emitting InP-based microlasers with cavity lengths of 600-100 μm. The required high reflectivity mirrors consist of a 2D ΓM-oriented triangular photonic crystal of air rods with a lattice constant of 350 nm. The lasers operate CW at room temperature with a threshold current of 29 mA and output power up to 4 mW for the shortest devices     

平板掺杂光子晶体中电磁波的缺陷模

为了研究1维平板掺杂光子晶体中电磁波的模式及其缺陷模特性,推导出1维平板掺杂光子晶体中电磁波的各个模式满足的条件,利用特征矩阵法计算出TE波和TM波各模式的缺陷模随模式量子数和平板厚度的变化规律,得出了一些不同于1维非受限掺杂光子晶体缺陷模的新特征。结果表明,电磁波的模式由模式量子数确定,缺陷模与模式量子数和平板厚度有关。     

Soliton spectral tunnelling in photonic crystal fibre with sub-wavelength core defect

A numerical study of soliton spectral tunnelling in an index-guiding photonic crystal fibre with a sub-wavelength central air core defect is presented. Specifically, for a fibre design where two regions of anomalous dispersion bracket a 90 nm wide region of normal dispersion, simulations show tunnelling from 1300 to 1475 nm across the forbidden normal dispersion regime, with near unity efficiency. In addition, this effect can be exploited to obtain over a factor of two nonlinear pulse compression by interrupting propagation at the distance at which soliton tunnelling occurs.     

质子注入型光子晶体垂直腔面发射激光器制备

在光子晶体垂直腔面发射激光器中采用质子注入工艺,使台面工艺变成纯平面工艺,降低了光子晶体结构制备难度,简化了器件制备,提高了器件的均匀性。质子注入型光子晶体垂直腔面发射激光器中的光子晶体结构,在电流限制孔小于光子晶体缺陷孔时,仍能控制器件光束及模式特性,该结果可用于优化器件阈值电流,制备高性能低阈值电流基横模器件。实验所设计制备的器件,在注入电流小于12.5 mA时,阈值电流2.1 mA,出光功率大于1 mW,远场发射角小于7,有效验证了光子晶体结构在质子注入型面发射激光器中的光束改善及模式控制作用。     

基于表面缺陷一维光子晶体Tamm态的研究

本文基于周期结构的布洛赫原理,从电磁场理论出发,用解析和数值的方法系统地研究了基于表面缺陷的半无限一维光子晶体Tamm态的形成条件,模式特征以及与无缺陷Tamm态之间的关系。 对TE波,缺陷Tamm态的频率范围向高低两个方向扩大;而对TM波,缺陷Tamm态的频率范围只向高频扩大, 而低频范围减小。缺陷折射率较大时, 缺陷Tamm态的色散曲线近似直线, 其群速度大小也近似等于光在单层缺陷里的传播速度。 通过调节缺陷层的折射率或者厚度可以方便地把缺陷Tamm态的频率设计到我们需要的范围。     

光子晶体缺陷模的偏振特性研究

为了了解光波在一维光子晶体的传输特性,利用传输矩阵方法进行了数值模拟,并研究了缺陷层厚度对缺陷模偏振特性的影响.结果表明,入射角的变化对光子晶体的禁带及缺陷模影响较大,它们都随入射角的增大向高频(短波)方向移动,s偏振的禁带宽度逐渐增宽而p偏振的禁带宽度变化不明显,p偏振的缺陷模频移较s偏振的稍大.随着入射角的增大,s偏振的缺陷模越来越细、品质因子逐渐增大,而p偏振的缺陷模变化趋势则刚好相反.     

近红外光谱区光子晶体禁带与KTP缺陷研究

光子晶体引入缺陷后形成的缺陷模在增益介质中将被放大形成激光,为了进一步明确缺陷的激光特性,首先从理论上分析了光子晶体的特征矩阵,接着得出了以下光子禁带特性:光带隙宽度随着周期数的增加而增大,但在周期数达到一定数值后其光带隙宽度是确定不变的;折射率比值越大,光带隙宽度越大;叠加不同中心波长的光子晶体可以简单、有效地拓展光带隙范围。在一维KTP光子晶体的禁带特性实验分析中得到了KTP缺陷的光子能带结构的波长响应曲线;随着温度的上升,KTP的折射率随之增大,进而缺陷模向长波长方向移动。上述研究对于微小光源的发展具有一定的理论和实际意义。     

缺陷奇偶性对光子晶体光传输特性的影响

采用传输矩阵法理论,研究缺陷参数奇偶性对含缺陷光子晶体（AB）m （ACx B）n （AB）m光传输特性的影响,研究结果表明：缺陷数目 n 的奇偶性仅影响缺陷模（透射峰）数目的奇偶性,即缺陷模数目的奇偶性与 n 对应;随着缺陷周期数 x 奇数倍增大,透射谱中的缺陷模向禁带中心靠拢,但缺陷模数目不变且等间距排列,随着 x 偶数倍增大,禁带两侧的两组缺陷模向禁带中心靠拢,且各组缺陷模数目与缺陷周期数 x 相关;缺陷光学厚度 DC 奇偶性对光子晶体透射谱的影响也很明显,随着 DC 增大且 DC ＜DA 时,分布在禁带右侧的缺陷模数目增加且向低频方向移动,随着 DC 增大且 DC ＞DA 时,分布于禁带左侧的缺陷模数目则减少但亦向低频方向移动。缺陷参数奇偶性对光子晶体透射谱的影响规律,为光子晶体设计可调性多通道光学滤波器件、光开关等提供理论借鉴,并为光子晶体的理论研究提供参考。