石墨烯量子點 (GQDs) 是一種新型光學增益材料，目前可用於具有高性價比和高效率元件的特性來作為光源。但截至目前為止，在學術期刊文獻當中，只有極少數關於GQDs產生誘發輻射，並應用於雷射輸出的研究與探討。在本碩士論文中，我們成功地製作出第一顆室溫光激發石墨烯量子點綠光面射型雷射( = 550 nm)。首先，藉由週期性成長堆疊Ta2O5 / SiO2兩種高折射係係數差異介電質材料，來設計並製作高光學品質的布拉格反射鏡 (Distributed Bragg Reflector, DBR)，其不僅提供與GQDs在輻射光譜上具有高重疊性，並同時在紫外光區域具有高光學穿透率。我們自行設計的DBR，將可見光波段 400 – 700 nm的光反射率高達95% 以上，並且在激發雷射光 ( = 355 nm) 有高達30% 的穿透率。我們再將兩片Ta2O5 / SiO2 DBR夾擠GQDs 作為光學增益介質，形成垂直型光學共振腔面射型雷射結構(Vertical-Cavity Surface-Emitting Laser, VCSEL)，透過脈衝雷射激發後 (5 ns pulse width , 10 Hz repetition rate,  = 355 nm)，最終在室溫下產生穩定的綠光雷射輸出。而我們的雷射是種無極化現象的多模態 (multi-mode) 雷射，較容易地去調控我們所需要的波長，也可以從 CIE1931 座標當中確認到我們的雷射波長是很穩定的，是可以藉由調控 GQDs 的直徑大小來控制我們雷射的發光波長。
藉由本實驗清楚地證明了GQDs能作為一種實用、成本低廉且高量子轉換效率的光學增益材料，展現GQD-VCSEL在寬色域雷射顯示器和投影式影像的高潛力應用。

Nonzero-bandgap graphene quantum dots (GQDs) are novel optical gain materials promising for solution-processed light sources with high cost efficiency and device performance. To date, there have only been a few reports on the realization of GQDs-based lasers. Herein, we demonstrate for the first time room-temperature lasing emission with green gamut from GQDs in a vertical optical cavity composed of Ta2O5/SiO2 dielectric distributed Bragg reflectors (DBRs). The lasing is enabled by the unique design of the DBR which not only provides a wide stopband spectrally overlapping with the emission of the GQDs but also allows high transmittance of optical excitation in the UV-light region. This demonstration is a clear evidence of the use of GQDs as optical gain materials and represents an important step forward towards their potential applications in wide-gamut laser displays and projectors.

[1] X. Yan et al., "Synthesis of large, stable colloidal graphene quantum dots with tunable size," vol. 132, no. 17, pp. 5944-5945, 2010.
[2] J. Shen et al., "Facile preparation and upconversion luminescence of graphene quantum dots," vol. 47, no. 9, pp. 2580-2582, 2011.
[3] S.-H. et al., "Unique properties of graphene quantum dots and their applications in photonic/electronic devices," vol. 50, no. 10, p. 103002, 2017.
[4] L. Ponomarenko et al., "Chaotic Dirac billiard in graphene quantum dots," vol. 320, no. 5874, pp. 356-358, 2008.
[5] K. A. Ritter et al., "The influence of edge structure on the electronic properties of graphene quantum dots and nanoribbons," vol. 8, no. 3, p. 235, 2009.
[6] D. Pan et al., "Hydrothermal route for cutting graphene sheets into blue‐luminescent graphene quantum dots," vol. 22, no. 6, pp. 734-738, 2010.
[7] L. L. Li et al., "A facile microwave avenue to electrochemiluminescent two‐color graphene quantum dots," vol. 22, no. 14, pp. 2971-2979, 2012.
[8] C. Luk et al., "An efficient and stable fluorescent graphene quantum dot–agar composite as a converting material in white light emitting diodes," vol. 22, no. 42, pp. 22378-22381, 2012.
[9] W. Zhang et al., "Observation of lasing emission from carbon nanodots in organic solvents," vol. 24, no. 17, pp. 2263-2267, 2012.
[10] M. Cao et al., "Tunable amplified spontaneous emission in graphene quantum dots doped cholesteric liquid crystals," vol. 28, no. 24, p. 245202, 2017.
[11] T. Gao et al., "Red, yellow, and blue luminescence by graphene quantum dots: syntheses, mechanism, and cellular imaging," vol. 9, no. 29, pp. 24846-24856, 2017.
[12] G. Haider et al., "Dirac point induced ultralow-threshold laser and giant optoelectronic quantum oscillations in graphene-based heterojunctions," vol. 8, no. 1, p. 256, 2017.
[13] T.-N. Lin et al., "Enhanced performance of GaN-based ultraviolet light emitting diodes by photon recycling using graphene quantum dots," vol. 7, no. 1, p. 7108, 2017.
[14] Z. Tian et al., "Ultraviolet-pumped white light emissive carbon dot based phosphors for light-emitting devices and visible light communication," vol. 11, no. 8, pp. 3489-3494, 2019.
[15] C. Dang et al., "Red, green and blue lasing enabled by single-exciton gain in colloidal quantum dot films," vol. 7, no. 5, p. 335, 2012.
[16] Y. C. Yao et al., "Coherent and polarized random laser emissions from colloidal CdSe/ZnS quantum dots plasmonically coupled to ellipsoidal Ag nanoparticles," vol. 5, no. 3, p. 1600746, 2017.
[17] Y. Li et al., "Room-temperature continuous-wave lasing from monolayer molybdenum ditelluride integrated with a silicon nanobeam cavity," vol. 12, no. 10, p. 987, 2017.
[18] D. G. Lidzey et al., "Strong exciton–photon coupling in an organic semiconductor microcavity," vol. 395, no. 6697, p. 53, 1998.
[19] H. Zhu et al., "Realization of lasing emission from graphene quantum dots using titanium dioxide nanoparticles as light scatterers," vol. 5, no. 5, pp. 1797-1802, 2013.
[20] S. Gottardo et al., "Resonance-driven random lasing," vol. 2, no. 7, p. 429, 2008.
[21] Y.-J. Lee et al., "Flexible random lasers with tunable lasing emissions," vol. 10, no. 22, pp. 10403-10411, 2018.
[22] K. D. Choquette et al., "Vertical-Cavity Surface-Emitting Lasers XX," in Proc. of SPIE Vol, 2016, vol. 9766, pp. 976601-1.
[23] R. Rodes et al., "High-speed 1550 nm VCSEL data transmission link employing 25 GBd 4-PAM modulation and hard decision forward error correction," vol. 31, no. 4, pp. 689-695, 2012.
[24] F. J. J. et al., "Recent advances of VCSEL photonics," vol. 24, no. 12, pp. 4502-4513, 2006.
[25] T.-C. Lu et al., "Continuous wave operation of current injected GaN vertical cavity surface emitting lasers at room temperature," vol. 97, no. 7, p. 071114, 2010.
[26] Y. Mei et al., "Quantum dot vertical-cavity surface-emitting lasers covering the ‘green gap’," vol. 6, no. 1, p. e16199, 2017.
[27] S. A. Khan et al., "Modeling of Low Power Multilayer Vertical Cavity Surface Emitting Laser," vol. 5, no. 5, pp. 155-160, 2015.
[28] C. C. Lee, Thin film optics and coating technology. 藝軒圖書, 2002.
[29] W. Chen et al., "Synthesis and applications of graphene quantum dots: A review," vol. 7, no. 2, pp. 157-185, 2018.
[30] H.-H. Cho et al., "Surface engineering of graphene quantum dots and their applications as efficient surfactants," vol. 7, no. 16, pp. 8615-8621, 2015.
[31] R. Tian et al., "Solvothermal method to prepare graphene quantum dots by hydrogen peroxide," vol. 60, pp. 204-208, 2016.
[32] L. Tang et al., "Deep ultraviolet photoluminescence of water-soluble self-passivated graphene quantum dots," vol. 6, no. 6, pp. 5102-5110, 2012.
[33] D. B. Shinde et al., "Electrochemical preparation of luminescent graphene quantum dots from multiwalled carbon nanotubes," vol. 18, no. 39, pp. 12522-12528, 2012.
[34] L. Bao et al., "Electrochemical tuning of luminescent carbon nanodots: from preparation to luminescence mechanism," vol. 23, no. 48, pp. 5801-5806, 2011.
[35] J. Peng et al., "Graphene quantum dots derived from carbon fibers," vol. 12, no. 2, pp. 844-849, 2012.