多相位256×256衍射微透镜的设计及其光学性能研究

介绍了衍射微透镜阵列的设计原理与制作工艺方法 ,在此基础上运用部分刻蚀法研制出适用于 3～ 5 μm波长多相位 2 5 6× 2 5 6衍射微透镜阵列。利用光通信半导体激光器和探测器建立了一套测试系统 ,并对所设计的多相位衍射微透镜阵列的衍射率和点扩散函数进行了测试 ,8相位和 16相位石英衍射微透镜的衍射率分别高达 80 .2 %和 87.5 % ,完全满足实际应用的要求。     

设计参数变化对衍射微透镜的影响

给出了多台阶衍射微透镜的设计公式,并阐述了旋转体时域有限差分法。通过采用该方法对设计的多台阶衍射微透镜进行分析,说明了设计参数(包括焦距、入射波长、透镜材料折射率)的变化与微透镜衍射效率、爱里斑半径、最大场强变化的关系,对部分结果的定性讨论与数值分析结果一致。     

锑化铟红外探测器的微透镜阵列设计及试验

台面型锑化铟红外焦平面探测器的制作工艺简单,量子效率高,但是填充因子较低且会随着像元尺寸的减小而进一步降低。减小台面腐蚀深度可以提高探测器的填充因子,但会增大串音。介绍了一种新型微透镜阵列的设计与制备方法,以提高锑化铟红外探测器的填充因子并减小串音。与现有的热回流微透镜阵列相比,该微透镜阵列的填充率、表面粗糙度以及尺寸均匀性能得到了较好的兼顾,可直接在锑化铟红外探测器表面制作,工艺简单。结果显示,探测器的串音降低26%,光响应提高22%。     

Numerical Simulation of Refractive-Microlensed HgCdTe Infrared Focal Plane Arrays Operating in Optical Systems

The optoelectronic performance of the mid-wavelength HgCdTe infrared focal plane array (IRFPA) with refractive microlenses integrated on its CdZnTe substrate has been numerically simulated. A reduced light-distribution model based on scalar Kirchhoff diffraction theory was adopted to reveal the true behavior of IRFPAs operating in an optical system under imaging conditions. The pixel crosstalk obtained and the energy-gathering characteristics demonstrated that the microlenses can delay the rise in crosstalk when the image point shifts toward pixel boundaries, and can restrict the major optical absorption process in any case within a narrow region around the pixel center. The dependence of the microlenses’ effects on the system's properties was also analyzed; this showed that intermediate relative aperture and small microlens radius are required for optimized device performance. Simulation results also indicated that for detectors farther from the center of the field of view, the efficacy of microlenses in crosstalk suppression and energy gathering is still maintained, except for a negligible difference in the lateral magnification from an ordinary array without microlenses.     

衍射微透镜阵列的光学性能研究及测试

对衍射微透镜阵列的光学性能进行理论上的研究,并提出一种测试微透镜阵列衍射效率和点扩散函数的方法,建立了一套测试系统,并对本所研制的128×128衍射微透镜阵列的衍射效率和点扩散函数进行了测试.测试结果证明本所研制的2位相的石英和硅衍射微透镜阵列的性能较好,均匀性较高;而由于工艺和光刻系统的限制,4位相衍射微透镜的制作还存在一些不足,这些都可以从所得到的衍射微透镜的点扩散函数曲线图和衍射效率看出.该方法适于测试具有微小单元尺寸、周期排列的微透镜阵列或单元的衍射效率和点扩散函数.     

Tracepro在OLED微透镜设计中的应用

有机电致发光从最初进行的研究直到今天,在许多方面都有了很大的突破,但目前仍存在着一些困难,例如器件的寿命就是比较关键的问题。如果器件具有较高的发光效率,便可在出射光子数相同的情况下,减少电子数的注入,从而降低了器件的焦耳热,提高了器件的寿命,所以提高OLED的量子效率是解决器件寿命问题的关键所在。利用微透镜提高器件的外量子效率可以取得明显的效果。本文探讨了Tracepro在OLED微透镜设计中的应用。     

Diffractive Microlens Array Monolithic Integration with PtSi Focal Plane array

Diffractive microlens arrays can completely collect the light at the focal plane and concentrate it into a smaller spot size on the detector plane, the photodetector area can be substantially reduced. Increased gamma radiation hardening and noise reduction result from the decrease in photodetector sensitive area. The diffractive microlens arrays have been designed by considering the correlative optical and processing parameters for PtSi focal plane array. They have been fabricated on the backside of PtSi focal plane array chip by successive photolithography and Ar⁺ ion-beam-etching technique. The alignment of microlens array with PtSi focal plane array was completed by a backside aligner with IR light source. The practical processes and fabrication method are discussed. The performance parameters of PtSi FPA with diffractive microlens array are presented.     

128×128硅衍射微透镜阵列的设计与制备

通过考虑互相关联的光学和工艺参数 ,设计了 3～ 5μm红外 12 8× 12 8硅衍射微透镜阵列。阵列中微透镜的孔径为 10 0μm,透镜 F数为 f / 1.5,微透镜阵列的中心距为 10 0μm。采用多次光刻和离子束刻蚀技术在硅衬底表面制备衍射微透镜阵列。对实际的工艺过程和制备方法进行了讨论 ,对制备出的 12 8× 12 8硅衍射微透镜阵列的光学性能和表面浮雕结构进行了测量。     

Microlens array fabrication by enhanced thermal reflow process: Towards efficient collection of fluorescence light from microarrays

This paper describes two enhanced resist reflow methods for the fabrication of microlens arrays and demonstrates their use for integrated biomolecular fluorescence detection on printed microarrays. A PDMS (polydimethylsiloxane) microlens array was fabricated by a double soft lithography approach using a photoresist microlens array as master mold. Additionally, by using both a careful control of the surface wettability and thermal treatments, we demonstrate the possibility to extend the resist reflow process in order to tune the diameters of microlens array over a large range by using a unique photomask pattern.We introduce an enhanced reflow on hydrophobic surfaces obtained by fluorosilane treatment and identify a threshold shrinkage temperature (T_shrinkage) of 140 °C, above which the diameter of microlenses can be then reduced down to 40% compared with the initial pattern on the photomask. Furthermore, on hydrophilic substrates, achieved by an accurate incomplete development of the photoresist, we demonstrate a nearly perfect linear dependency (1.4 μm/°C) of microlens diameter spreading up to 70% the initial diameter inside a temperature reflow window of 110-140 °C. For both approaches, above a freezing temperature (T_freezing) of 170 °C, the microlens profile characteristics are temperature independent.By using high numerical aperture microlens array, we provide a proof of concept for the integration and enhanced light collection of the fluorescent signals collected form a microarray of fluorescent spots thus showing the potential of the concept for biophotonic integration.     

固体浸没式红外超表面透镜设计

红外焦平面阵列在各类红外成像系统中发挥着巨大的作用。为提升红外焦平面的工作温度、量子效率和灵敏度,通常使用微透镜阵列作为红外焦平面的聚光器。当前微透镜阵列的制作材料通常与红外探测器材料不同,因此在集成装配时需要额外的工艺手段,工艺难度较大且效率较低。利用微纳光学超表面技术体系,可以在红外探测器衬底材料上直接制作平面式的固体浸没型微透镜阵列,实现前置微透镜与红外焦平面的单片集成。文中以红外探测领域最有潜力的锑化物Ⅱ类超晶格红外探测器为应用目标,设计了一种基于GaSb衬底的固体浸没式红外超表面透镜。设计的超表面透镜在中波红外波段工作,能适用于所有入射偏振。器件设计焦距为100 μm,理论上在目标波长下的最高聚焦效率达到70.7%,数值孔径(NA)达到1.15。该设计可以推动微透镜阵列向扁平、超薄、轻量的方向发展,简化微透镜阵列与红外焦平面阵列的集成工艺,有望提升红外焦平面的探测效率,并降低制造成本。     

Design, Fabrication, and Integration Technology of Large-Scale Microlens Array for Infrared Charge Coupled Device Application

Infrared charge coupled device (IRCCD) integration with microlens array is an effective method for improving the detecting sensitivity of IRCCD sensors. In this paper, we present the diffractive microlens array (MLA), which is manufactured by the submicron photolithography technology and magnetically enhanced reactive ion etching (MERIE) on infrared quartz substrate. The integration procedure between microlens array and PtSi Schottky-barrier IRCCD chip is introduced in detail. The optical response of IRCCD sensor with microlens array is tested and the average response increases 0.23 in the spectral range of 1.2～5.0 μm. The measuring results show that the large-scale diffractive microlens array is able to improve the detecting sensitivity of IRCCD and that the integration technology mentioned is available.     

一种基于空间光调制器的微透镜阵列制备技术

提出了一种基于空间光调制器的并行光刻制备微透镜阵列的技术。采用数字微反射镜器件输入光刻图形,结合热回流技术,制作任意结构和排布的微透镜阵列。无限远校正显微微缩光学系统的长焦深保证了深纹光刻的实现,热回流法提供了良好的表面光滑度。与传统逐层并行光刻和掩模曝光技术相比,提出的技术方案更加便捷灵活,特别适合制作特征尺寸在数微米至百微米的微透镜阵列器件。得到的微透镜阵列模版经过电铸转移为金属模具,利用紫外卷对卷纳米压印技术在柔性基底上制备微透镜阵列器件,在超薄液晶显示、有机发光二极管(OLED)照明等领域有广泛应用。     

Coupling efficiency enhancement in organic light-emitting devices using microlens array-theory and experiment

Microlens arrays are introduced on glass substrates to improve the out-coupling efficiency of organic light-emitting devices (OLEDs). The microlenses suppress waveguiding loss in the substrate. A theoretical model, based on electromagnetic wave propagation and geometric ray tracing, is developed to simulate the enhancement effects and optimize the structure parameters of the lens pattern. A simple soft-lithography approach is employed to fabricate the microlens array on glass substrates. With the use of an optimized lens pattern, an increase of over 85% in the coupling efficiency of the OLED is expected theoretically. An increase of 70% in the coupling efficiency is achieved experimentally, without detrimental effect to the electrical performance of the OLED.     

非梯度折射率型面阵平面微透镜

采用常规的光刻热熔法及灰度掩模技术,结合离子束蚀刻与溅射制作面阵非梯度折射率型平面折射和平面衍射微透镜,定性分析了不同的工艺条件下所得到的平面端面微光学折种和形貌特征。给出了在石英衬底表面通过光刻热熔工艺和氩离子束蚀刻所得到的两种球面及圆弧轮廓特征的面阵册形掩模的表面探针测试曲线,对平面微透镜阵列与IRCCD成像芯片和半导体激光器阵列的集成结构作了初步分析。     

Fabrication of a 100%fill-factor silicon microlens array

正A simple method has been developed for the fabrication of a silicon microlens array with a 100%fill factor and a smooth configuration.The microlens array is fabricated by using the processes of photoresist(SU8- 2005) spin coating,thermal reflow,thermal treatment and reactive ion etching(RIE).First,a photoresist microlens array on a single-polished silicon substrate is fabricated by both thermal reflow and thermal treatment technologies. A typical microlens has a square bottom with size of 25μm,and the distance between every two adjacent microlenses is 5μm.Secondly,the photoresist microlens array is transferred to the silicon substrate by RIE to fabricate the silicon microlens array.Experimental results reveal that the silicon microlens array could be formed by adjusting the quantities of the reactive ion gases of SF_6 and O_2 to proper values.In this paper,the quantities of SF_6 and O_2 are 60 sccm and 50 sccm,respectively,the corresponding etch ratio of the photoresist and the silicon substrate is 1 to 1.44.The bottom size and height of a typical silicon microlens are 30.1μm and 3μm,respectively. The focal lengths of the microlenses ranged from 15.4 to 16.6μm.     

Effect of various microlens parameters on enhancement of light outcoupling efficiency of organic light emitting diode

Since organic light emitting diode (OLED) is a multilayer device where each layer has different refractive index, total internal reflection (TIR) plays an important role in limiting the efficiency of an OLED. Due to the presence of TIR, a major portion of light is trapped within the device in various wave guiding modes. Of the total light trapped in an OLED, we address only the part that is lost due to wave guiding mode arising from refractive index mismatch at the glass-air interface. Microlens array, to improve luminance, is a method that can be externally applied to the OLEDs without altering its electrical characteristics and is easy to use. Microlens arrays ranging from 10 to 40 μm have been fabricated using an organic elastomeric material polydimethylsiloxane (PDMS) by mold transfer technique. Maximum improvement of 25% in outcoupling efficiency for blue OLED is reported upon using the microlens array with diameter 10 μm. For a given diameter of microlens, out-coupling efficiency of OLED increases as height to diameter (H/D) ratio of microlens array approaches 0.5 (perfect hemisphere). It is also observed that outcoupling efficiency increases with the diameter of microlens for a given H/D ratio. The best luminescence improvement was observed for blue OLED, which can be explained by the higher refractive index of PDMS at lower wavelengths.     

一种掩埋式复眼微透镜阵列

模仿生物复眼,采用光刻离子交换法,在球面玻璃基片中制作了折射率呈三维梯度变化、排列紧密和光学性能良好的微透镜阵列。单元微透镜孔径呈正六角形,光斑大小为4．92μm,相邻透镜元中心距为0．5mm,掩埋透镜高为0．194mm。微透镜阵列具有对称均匀的光学特性,截距自中心至边缘逐渐变小,数值孔径（N．A．）自中心向边缘逐渐变...     

High performance SWIR HgCdTe detector arrays

Short wave infrared (SWIR) devices have been fabricated using Rockwell’s double layer planar heterostructure (DLPH) architecture with arsenic-ion implanted junctions. Molecular beam epitaxially grown HgCdTe/CdZnTe multilayer structures allowed the thin, tailored device geometries (typical active layer thickness was ∼3.5 μm and cap layer thickness was ∼0.4 μm) to be grown. A planar-mesa geometry that preserved the passivation advantages of the DLPH structure with enhanced optical collection improved the performance. Test detectors showed Band 7 detectors performing near the radiative limit (∼3-5X below theory). Band 5 detector performance was ∼4-50X lower than radiative limited performance, apparently due to Shockley-Hall-Read recombination. We have fabricated SWIR HgCdTe 256 × 12 × 2 arrays of 45 um × 45 μm detector on 45 μm × 60 μm centers and with cutoff wavelength which allows coverage of the Landsat Band 5 (1.5−1.75 μm) and Landsat Band 7 (2.08−2.35 μm) spectral regions. The hybridizable arrays have four subarrays, each having a different detector architecture. One of the Band 7 hybrids has demonstrated performance approaching the radiative theoretical limit for temperatures from 250 to 295K, consistent with test results. D* performance at 250K of the best subarray was high, with an operability of ∼99% at 10¹² cm Hz^1/2/W at a few mV bias. We have observed 1/f noise below 8E-17 AHz ^1/2 at 1 Hz. Also for Band 7 test structures, Ge thin film diffractive microlenses fabricated directly on the back side of the CdZnTe substrate showed the ability to increase the effective collection area of small (nominally <20 μm μm) planar-mesa diodes to the microlens size of 48 urn. Using microlenses allows array performance to exceed 1-D theory up to a factor of 5.     

Highly uniform vertical-cavity surface-emitting lasers integratedwith microlens arrays

In this paper, work is described on the fabrication of highly uniform 8×8 arrays of GaAs-AlGaAs vertical-cavity surface-emitting lasers (VCSEL's). Oxide-confined VCSEL arrays show an average threshold current of 0.74±0.02 mA, an average output power of 2.05±0.03 mW at 8 mA and an average power conversion efficiency of 14.3%. Their wavelength is measured to be 967±0.35 nm over the array. In addition, we describe the alignment and integration of these device arrays with arrays of refractive microlenses to allow beam shaping typically required in system applications     

菲涅耳微透镜列阵衍射效率的测试

提出了一种测试菲涅耳微透镜列阵衍射效率的有效方法，采用Ｈｅ－Ｎｅ激光器作为测试光源，利用计算机辅助测试构成了一个衍射效率测试光路系统，对测试原理进行了分析，该方法具有简便易行的特点，适于测试具有微小单元尺寸、周期密排的二元微光学元件的衍射效率。