• Photonics Research
  • Vol. 10, Issue 2, 269 (2022)
Che-Hsuan Huang1, Yu-Tang Cheng2, Yung-Chi Tsao3, Xinke Liu4, and Hao-Chung Kuo5
Author Affiliations
  • 1College of Materials Science and Engineering, Guangdong Research Center for Interfacial Engineering of Functional Materials, Institute of Microelectronics (IME), Shenzhen University, Shenzhen 518060, China
  • 2Department of Photonics & Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, Taiwan Yang Ming Chiao Tung University & Taiwan Chiao Tung University, Hsinchu 30010, China
  • 3Department of Computer Science, University of Liverpool, Liverpool, UK
  • 4College of Materials Science and Engineering, Guangdong Research Center for Interfacial Engineering of Functional Materials, Institute of Microelectronics (IME), Shenzhen University, Shenzhen 518060, China
  • 5Department of Photonics & Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, Taiwan Yang Ming Chiao Tung University & Taiwan Chiao Tung University, Hsinchu 30010, China
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    DOI: 10.1364/PRJ.441188 Cite this Article Set citation alerts
    Che-Hsuan Huang, Yu-Tang Cheng, Yung-Chi Tsao, Xinke Liu, Hao-Chung Kuo. Micro-LED backlight module by deep reinforcement learning and micro-macro-hybrid environment control agent[J]. Photonics Research, 2022, 10(2): 269 Copy Citation Text show less
    (a) Schematic diagram of micro-LED backlight module; (b) schematic diagram of LED with DBR structure; (c) highly-reflective surface substrate; (d) etching structure of the receiver.
    Fig. 1. (a) Schematic diagram of micro-LED backlight module; (b) schematic diagram of LED with DBR structure; (c) highly-reflective surface substrate; (d) etching structure of the receiver.
    Workflow for optimizing micro-LED backlight module: (a) the process of deep reinforcement learning and (b) the process of the virtual-realistic experiment.
    Fig. 2. Workflow for optimizing micro-LED backlight module: (a) the process of deep reinforcement learning and (b) the process of the virtual-realistic experiment.
    (a) Workflow of environment control agent and schematic diagram of the virtual-realistic experiment; (b) principle of kernel1: Gaussian and Lambertian reflection; (c) principle of kernel2: BSDF properties.
    Fig. 3. (a) Workflow of environment control agent and schematic diagram of the virtual-realistic experiment; (b) principle of kernel1: Gaussian and Lambertian reflection; (c) principle of kernel2: BSDF properties.
    Workflow of DDQN network.
    Fig. 4. Workflow of DDQN network.
    Virtual-realistic experiment: (a) single light pattern analysis; (b) module pattern analysis.
    Fig. 5. Virtual-realistic experiment: (a) single light pattern analysis; (b) module pattern analysis.
    Result of reinforcement learning: (a) uniformity for every iteration with reward function1; (b) uniformity for every iteration with reward function2; (c) uniformity for every iteration with reward function3; (d) the best result by reward function1; (e) the best result by reward function2; (f) the best result by reward function3.
    Fig. 6. Result of reinforcement learning: (a) uniformity for every iteration with reward function1; (b) uniformity for every iteration with reward function2; (c) uniformity for every iteration with reward function3; (d) the best result by reward function1; (e) the best result by reward function2; (f) the best result by reward function3.
    Demonstration of the micro-LED backlight module.
    Fig. 7. Demonstration of the micro-LED backlight module.
    Influence of DBR structure: (a) light pattern with state Sb3′, (b) light pattern with state Sb3, and (c) uniformity of Sb3 and Sb3′.
    Fig. 8. Influence of DBR structure: (a) light pattern with state Sb3, (b) light pattern with state Sb3, and (c) uniformity of Sb3 and Sb3.
    Schematic of resonant loss for the micro-LED backlight module.
    Fig. 9. Schematic of resonant loss for the micro-LED backlight module.
    Action No.Action DefinitionVariation Symbol
    a1Add distanceD
    a2Reduce distanceD
    a3Add widthW
    a4Reduce widthW
    a5Add spacingS
    a6Reduce spacingS
    a7Add thicknessT
    a8Reduce thicknessT
    a9Add DBR pairsDBR
    a10Reduce DBR pairsDBR
    Table 1. Definition List of Action
    State No.State DefinitionVariation symbol
    S1Value of distanceD
    S2Value of spacingW
    S3Value of DBR pairsS
    S4Value of thicknessT
    S5Value of widthDBR
    Table 2. Definition List of State
    No.ParametersVariation SymbolRange
    1Distance from receiver to LEDD100–180 μm
    2LED widthW10–100 μm
    3LED spacingS300–700 μm
    4Thickness of LEDT5–55 μm
    5DBR-BSDF pairsDBR4.5–9.5 pairs
    Table 3. Definition List for Range of Parameters
    No.ParametersValue
    1Bulk of GaN-based light-emitting diodesRefraction index2.4869
    2High-reflectivity white bottom surface of moduleGaussian type 5° with 97%
    3Receiver reflectivityLambertian with 35%
    4Index of DBR material (AIN/GaN)nAIN=2.1793/nGaN=2.4869
    5Thickness of DBR material (AIN/GaN)tAIN=51.6  nm/tGaN=45.2  nm
    Table 4. Results of Virtual-Realistic Experiment
    Best StateReward FormulaParametersNumber of IterationsBest Uniformity
    Sb1(UniformitynewUniformityold)/100D=0.18  mm, W=0.04  mm, S=0.4  mm, T=0.02  mm, DBR=5.5pairs28983.97%
    Sb2(Uniformity75)3/1000D=0.16  mm, W=0.02  mm, S=0.46  mm, T=0.015  mm, DBR=5.5pairs18386.51%
    Sb3(Uniformity79)3/1000D=0.18  mm, W=0.028  mm, S=0.5  mm, T=0.035  mm, DBR=6.5  pairs24990.32%
    Table 5. Best Uniformity for Different Reward Functions
     Number of IterationsTime (h)Optimal Result
    Entire loop106,920297Uniformity: 89.61%
    Designing agent16,00053.3Uniformity: 90.32%
    Table 6. Work Efficiency of Designing Agent
    Che-Hsuan Huang, Yu-Tang Cheng, Yung-Chi Tsao, Xinke Liu, Hao-Chung Kuo. Micro-LED backlight module by deep reinforcement learning and micro-macro-hybrid environment control agent[J]. Photonics Research, 2022, 10(2): 269
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