Yong Kang Eugene Tay received his B.Sc. (2015) degree and Ph.D. (2020) in Physics from Nanyang Technological University, (NTU), Singapore, where he pursued his Ph.D. under the supervision of Prof. Tze Chien Sum. Eugene is presently a Research Engineer at KLA-Tencor. His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures with a focus on colloidal nanocrystals; charge carrier dynamics in light emission; optical gain and lasing.Huajun He received his B.Sc. (2014) in Materials Science and Engineering (MSE) and honorary certificate of Chu Kochen Honors College from Zhejiang University (ZJU), China, and his Ph.D. (2019) degree in MSE from ZJU, China. He is currently working as a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include advanced imaging materials with a focus on aqueous colloidal nanocrystals and metal-organic frameworks; ultrafast spectroscopy study of photophysics in photonic funtioncal materials; multiphoton excitation, optical gain and lasingXiangling Tian received his B.Sc. (2010) in Physics from Qufu Normal University, China, M.Sc. (2013) in Condensed Matter Physics from Zhejiang Normal University, China and Ph.D. (2018) degree in Materials Science and Engineering from South China University of Technology, China. He was a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include light-matter interactions, photonic/plasmonic nanolasers, laser spectroscopy and novel physical phenomena emerging in nanoscale structures.Mingjie Li received his B.Sc. (2006) and M.Sc. (2009) degrees in Physics from Lanzhou University, China, and his Ph.D. (2013) degree under the supervision of Prof. Tze Chien Sum in Physics and Applied Physics from NTU, Singapore. He is currently an Assistant Professor at the Department of Applied Physics at The Hong Kong Polytechnic University.His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures; charge carrier dynamics in light harvesting, emitting and lasing materials and devices.Tze Chien Sum received his B.Sc. (1999), M.Sc. (2000) and Ph.D. (2005) degrees in Physics from the National University of Singapore. He is presently a Professor of Physics at the NTU’s School of Physical and Mathematical Sciences (SPMS), where he leads the Femtosecond Dynamics Laboratory. He holds dual appointments of the Director of Institute of Advanced Studies and the Associate Dean (Research), College of Science. His current research focuses on investigating light–matter interactions; energy and charge transfer mechanisms; and probing carrier and quasi-particle dynamics in a broad range of emergent nanoscale, light harvesting and light emitting systems.

• 1. Fundamentals of Lasers.- 2. Photophysics behind Perovskite Lasers.- 3. Perovskites as Viable Gain Media.- 4. Fabricating Techniques of Practical Lasing Resonator.- 5. Conclusion.

Yong Kang Eugene Tay received his B.Sc. (2015) degree and Ph.D. (2020) in Physics from Nanyang Technological University, (NTU), Singapore, where he pursued his Ph.D. under the supervision of Prof. Tze Chien Sum. Eugene is presently a Research Engineer at KLA-Tencor. His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures with a focus on colloidal nanocrystals; charge carrier dynamics in light emission; optical gain and lasing.Huajun He received his B.Sc. (2014) in Materials Science and Engineering (MSE) and honorary certificate of Chu Kochen Honors College from Zhejiang University (ZJU), China, and his Ph.D. (2019) degree in MSE from ZJU, China. He is currently working as a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include advanced imaging materials with a focus on aqueous colloidal nanocrystals and metal-organic frameworks; ultrafast spectroscopy study of photophysics in photonic funtioncal materials; multiphoton excitation, optical gain and lasingXiangling Tian received his B.Sc. (2010) in Physics from Qufu Normal University, China, M.Sc. (2013) in Condensed Matter Physics from Zhejiang Normal University, China and Ph.D. (2018) degree in Materials Science and Engineering from South China University of Technology, China. He was a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include light-matter interactions, photonic/plasmonic nanolasers, laser spectroscopy and novel physical phenomena emerging in nanoscale structures.Mingjie Li received his B.Sc. (2006) and M.Sc. (2009) degrees in Physics from Lanzhou University, China, and his Ph.D. (2013) degree under the supervision of Prof. Tze Chien Sum in Physics and Applied Physics from NTU, Singapore. He is currently an Assistant Professor at the Department of Applied Physics at The Hong Kong Polytechnic University.His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures; charge carrier dynamics in light harvesting, emitting and lasing materials and devices.Tze Chien Sum received his B.Sc. (1999), M.Sc. (2000) and Ph.D. (2005) degrees in Physics from the National University of Singapore. He is presently a Professor of Physics at the NTU’s School of Physical and Mathematical Sciences (SPMS), where he leads the Femtosecond Dynamics Laboratory. He holds dual appointments of the Director of Institute of Advanced Studies and the Associate Dean (Research), College of Science. His current research focuses on investigating light–matter interactions; energy and charge transfer mechanisms; and probing carrier and quasi-particle dynamics in a broad range of emergent nanoscale, light harvesting and light emitting systems.

• 1. Fundamentals of Lasers.- 2. Photophysics behind Perovskite Lasers.- 3. Perovskites as Viable Gain Media.- 4. Fabricating Techniques of Practical Lasing Resonator.- 5. Conclusion.

Yong Kang Eugene Tay received his B.Sc. (2015) degree and Ph.D. (2020) in Physics from Nanyang Technological University, (NTU), Singapore, where he pursued his Ph.D. under the supervision of Prof. Tze Chien Sum. Eugene is presently a Research Engineer at KLA-Tencor. His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures with a focus on colloidal nanocrystals; charge carrier dynamics in light emission; optical gain and lasing.Huajun He received his B.Sc. (2014) in Materials Science and Engineering (MSE) and honorary certificate of Chu Kochen Honors College from Zhejiang University (ZJU), China, and his Ph.D. (2019) degree in MSE from ZJU, China. He is currently working as a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include advanced imaging materials with a focus on aqueous colloidal nanocrystals and metal-organic frameworks; ultrafast spectroscopy study of photophysics in photonic funtioncal materials; multiphoton excitation, optical gain and lasingXiangling Tian received his B.Sc. (2010) in Physics from Qufu Normal University, China, M.Sc. (2013) in Condensed Matter Physics from Zhejiang Normal University, China and Ph.D. (2018) degree in Materials Science and Engineering from South China University of Technology, China. He was a research fellow supervised by Prof. Tze Chien Sum in NTU Singapore. His research interests include light-matter interactions, photonic/plasmonic nanolasers, laser spectroscopy and novel physical phenomena emerging in nanoscale structures.Mingjie Li received his B.Sc. (2006) and M.Sc. (2009) degrees in Physics from Lanzhou University, China, and his Ph.D. (2013) degree under the supervision of Prof. Tze Chien Sum in Physics and Applied Physics from NTU, Singapore. He is currently an Assistant Professor at the Department of Applied Physics at The Hong Kong Polytechnic University.His research interests include ultrafast spectroscopy study of photophysics in semiconductor and perovskite nanostructures; charge carrier dynamics in light harvesting, emitting and lasing materials and devices.Tze Chien Sum received his B.Sc. (1999), M.Sc. (2000) and Ph.D. (2005) degrees in Physics from the National University of Singapore. He is presently a Professor of Physics at the NTU’s School of Physical and Mathematical Sciences (SPMS), where he leads the Femtosecond Dynamics Laboratory. He holds dual appointments of the Director of Institute of Advanced Studies and the Associate Dean (Research), College of Science. His current research focuses on investigating light–matter interactions; energy and charge transfer mechanisms; and probing carrier and quasi-particle dynamics in a broad range of emergent nanoscale, light harvesting and light emitting systems.

• 1. Fundamentals of Lasers.- 2. Photophysics behind Perovskite Lasers.- 3. Perovskites as Viable Gain Media.- 4. Fabricating Techniques of Practical Lasing Resonator.- 5. Conclusion.