Ultrafast Laser Optics and Coherent Microscopy

Guoqing Chang - Group Leader

Education

2000 – 2006 Ph.D. in Electrical Engineering, major in optics, minor in communication, the
University of Michigan
Thesis title: “Nonlinear propagation and high power THz generation using ultrashort pulses”
Co-advisors: Professor Theodore B. Norris and Professor Herbert G. Winful
1998 – 2000 M.S. in Electronics Engineering, major in optoelectronics, Tsinghua University
Thesis title: “Optoelectronic oscillator (OEO) and its application for clock recovery”
1994 – 1998 B.S. in Electronics Engineering, major in optoelectronics, Tsinghua University



Research and Professional Experience

2012 – Helmholtz Independent Group Leader, Head of Ultrafast Fiber Optics group, Center for Free-Electron Laser Science (CFEL), Deutsches Elektronen-Synchrotron (DESY), Germany.

2012 – Visiting Scientist, Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology.

2008 – 2012 Postdoctoral Research Associate, Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology.
Advisor: Professor Franz X. Kärtner

2006 – 2008 Postdoctoral Research Fellow, Department of Electrical Engineering and Computer Science, and Center for Ultrafast Optical Science, the University of Michigan.


2000 – 2006 Graduate Student Research Assistant, Department of Electrical Engineering and Computer Science, and Center for Ultrafast Optical Science and FOCUS center, the University of Michigan.



Publications

[37] A. G. Glenday, C. –H. Li, N. Langellier, G. Q. Chang, L.-J. Chen, G. Furesz, A. Zibrov, F. X. Kärtner, D. F. Phillips, D. Sasselov, A. Szentgyorgyi, and R. L. Walsworth, “Operation of a broadband visible-wavelength astro-comb with a high-resolution astrophysical spectrograph” Optica 2, 250 (2015)

[36] W. Liu, D. N. Schimpf, T. Eidam, J. Limpert, A. Tuennermann, F. X. Kaertner, G. Q. Chang, “Pre-chirp managed nonlinear amplification in fibers delivering 100 W, 60 fs pulse” Opt. Lett. 40, 151 (2015).

[35] J. K. Lim, H. -W. Chen, S. H. Xu, Z. M. Yang, G. Q. Chang, and F. X. Kaertner, “3 GHz, Watt-level femtosecond Raman soliton source,” Opt. Lett. 39, 2060 (2014)

[34] S. –H Chia, L. –J Chen, Q. Zhang, O. D. Muecke, G. Q. Chang, and F. X. Kaertner, “Broadband continuum generation in mode-locked lasers with phase-matched output couplers,” Opt. Lett. 39, 1445 (2014)
 
[33] H. -W. Chen, H. Zia, J. K. Lim, S. H. Xu, Z. M. Yang, F. X. Kaertner, and G. Q. Chang, “3 GHz, Yb-fiber laser based, few-cycle ultrafast source at the Ti:sapphire laser wavelength,” Opt. Lett. 38, 4927 (2013)

[32] J. K. Lim, H. -W. Chen, G. Q. Chang, and F. X. Kaertner, “Frequency comb based on a narrowband Yb-fiber oscillator: pre-chirp management for self-referenced fCEO stabilization,” Opt. Express 21, 4531 (2013)

[31] H. -W. Chen, J. K. Lim, S. –W. Huang, D. N. Schimpf, F. X. Kaertner, and G. Q. Chang, “Optimization of femtosecond Yb-doped fiber amplifiers for high-quality pulse compression,” Opt. Express 20, 28672 (2012)

[30] G. Q. Chang, C. –H. Li, D. F. Phillips, A. Szentgyorgyi, R. L. Walsworth, and F. X. Kaertner, “Optimization of filtering schemes for broadband astro-combs,” Opt. Express 20, 24987 (2012)
 
[29] H. -W. Chen, G. Q. Chang, S. H. Xu, Z. M. Yang, and F. X. Kaertner, “3 GHz, fundamentally mode-locked, femtosecond Yb-fiber laser,” Opt. Lett. 37, 3522, (2012)

[28] C. –H. Li, G. Q. Chang, A. Glenday, D. F. Phillips, F. X. Kaertner, and R. L. Walsworth, “Conjugate Fabry-Perot cavity pair for astro-combs,” Opt. Lett. 37, 3090 (2012)

[27] D. F. Phillips, A. G. Glenday, C. –H. Li, C. Cramer, G. Furesz, G. Q. Chang, A. J. Benedick, L.-J. Chen, F. X. Kärtner, S. Korzennik, D. Sasselov, A. Szentgyorgyi, and R. L. Walsworth, “Calibration of an astrophysical spectrograph below 1 m/s using a laser frequency comb” Opt. Express 20, 13711 (2012)

[26] X. Q. Ma, C. –H. Liu, G. Q. Chang, and A. Galvanauskas, “Angular-momentum coupled optical waves in chirally-coupled-core fibers,” Opt. Express 19, 26515 (2011)

[25] G. Q. Chang, L. –J. Chen, and F. X. Kaertner, “Fiber-optic Cherenkov radiation in the few-cycle regime,” Opt. Express 19, 6636 (2011)

[24] H. –W. Chen, T. Sosnowski, C. –H. Liu, L. –J Chen, J. Birge, A. Galvanauskas, F. X. Kaertner, and G. Q. Chang, “Chirally-coupled-core Yb-fiber laser delivering 80-fs pulses with diffraction-limited beam quality warranted by a high-dispersion-mirror based compressor,” Opt. Express 18, 24699 (2010)

[23] L.-J. Chen, G. Q. Chang, C.-H. Li, A. J. Benedick, D. F. Phillips, R. L. Walsworth, and F. X. Kärtner, “Broadband dispersion-free optical cavities based on zero group delay dispersion mirror sets,” Opt. Express 18, 23204 (2010) (selected as research highlight by Nature Photonics, January 2011)

[22] A. J. Benedick, G. Q. Chang, J. R. Birge, L.-J. Chen, A. G. Glenday, C.-H. Li, D. F. Phillips, A. Szentgyorgyi, S. Korzennik, G. Furesz, R. L. Walsworth, and F. X. Kärtner, “Visible wavelength astro-comb,” Opt. Express 18, 19175 (2010)

[21] G. Q. Chang, L. –J. Chen, and F. X. Kaertner, “Highly efficient Cherenkov radiation in photonic crystal fibers for broadband visible wavelength generation,” Opt. Lett. 35, 2361 (2010) (selected as research highlight by Nature Photonics, September 2010)
      
[20] C. –H. Li, A. Glenday, A. Benedick, G. Q. Chang, L. –J. Chen, C. Cramer, P. Fendel, G. Furesz, F. X. Kaertner, S. Korzennik, D. F. Phillips, D. Sasselov, A. Szentgyorgyi, R. L. Walsworth, “In-situ determination of astro-comb calibration lines to better than 10 cm/s,” Opt. Express 18, 13239 (2010)

[19] G. Q. Chang, C. –H. Li, D. F. Phillips, R. L. Walsworth, and F. X. Kaertner, “Toward a broadband astro-comb: Effects of nonlinear spectral broadening in optical fibers,” Opt. Express 18, 12736 (2010)
      
[18] G. Q. Chang, M. Rever, V. Smirnov, L. Glebov, and A. Galvanauskas, “Femtosecond
  Yb-Fiber CPA system based on Chirped-Volume-Bragg-Gratings,” Opt. Lett. 34, 2952
   (2009)

[17] G. Q. Chang, C. J. Divin, J. Yang, M. A. Musheinish, S. L. Williamson, A. Galvanauskas, and T. B. Norris, “GaP waveguide emitters for high power broadband THz generation pumped by Yb-doped fiber lasers,” Opt. Express 15, 16308 (2007)

[16] K. H. Liao, A. G. Mordovanakis, B. Hou, G. Q. Chang, M. Rever, G. A. Mourou, J. Nees, and A. Galvanauskas, “Generation of hard X-rays using an ultrafast fiber laser system,” Opt. Express 15, 13942 (2007)

[15] G. Q. Chang, C. J. Divin, C. H. Liu, S. L. Williamson, A. Galvanauskas, and T. B. Norris, “Generation of radially polarized THz pulses via velocity mismatched optical rectification,” Opt. Lett. 32, 433 (2007)

[14] G. Q. Chang, C. J. Divin, C. H. Liu, S. L. Williamson, A. Galvanauskas, and T. B. Norris, “Power scalable compact THz system based on an ultrafast Yb-doped fiber amplifier,” Opt. Express 14, 7909 (2006)

[13] G. Q. Chang, H. G. Winful, A. Galvanauskas, and T. B. Norris, “Incoherent self- similarities of the coupled amplified nonlinear Schrödinger equations,” Phys. Rev. E 73, 016616 (2006)

[12] G. Q. Chang, H. G. Winful, A. Galvanauskas, and T. B. Norris, “Self-similar parabolic beam generation and propagation,” Phys. Rev. E 72, 016609 (2005)
 
[11] G. Q. Chang, A. Galvanauskas, H. G. Winful, and T. B. Norris, “Dependence of Parabolic pulse amplification on stimulated Raman scattering and gain bandwidth,” Opt. Lett. 29, 2647 (2004)

[10] J. Y. Ye, G. Q. Chang, T. B. Norris, C. Tse, M. J. Zohdy, K. W. Hollman, M. O'Donnell, J. R. Baker, “Trapping cavitation bubbles with a self-focused laser beam,” Opt. Lett. 29, 2136 (2004)

[9] G. Q. Chang, T. B. Norris, and H. G. Winful, “Optimization of supercontinuum generation in photonic crystal fibers for pulse compression,” Opt. Lett. 28, 546 (2003)

[8] C. Y. Lou, L. Huo, G. Q. Chang, and Y. Z. Gao, “A novel approach to clock division and frame clock extraction,” Chinese J. Electron. 11, 58 (2002)

[7] C. Y. Lou, L. Huo, G. Q. Chang, and Y. Z. Gao, “Experimental study of clock division using the optoelectronic oscillator,” IEEE Photonic. Tech. Lett., 14, 1178 (2002)

[6] M. Han, C. Y. Lou, Y. Wu, G. Q. Chang, Y. Z. Gao, and Y. H. Li, “Generation of pedestal-free 10 GHz pulses from a comb-like dispersion profiled fiber compressor and its application in supercontinuum generation,” Chinese Phys. Lett. 17, 806 (2000)

[5] G. Q. Chang, C. Y. Lou, Y. H. Li, Y. Z. Gao, and B. K. Zhou, “Novel analytic theory for laser mode-locking,” Int. J. IRMMW 20, 2063 (1999)

[4] Y. H. Li, C. Y. Lou, G. Q. Chang, and Y. Z. Gao, “Theoretical study on the actively mode-locked fiber laser with the q-parameter and the ABCD law,” IEEE Photonic. Tech. Lett., 11, 1590 (1999)

[3] G. Q. Chang, C. Y. Lou, Y. H. Li, and Y. Z. Gao, “Novel analytic theory for actively mode-locked fiber laser,” Acta Physica Sinica 8, 838 (1999)

[2] Y. H. Li, C. Y. Lou, J. Wu, G. Q. Chang, B. Y. Wu, and Y. Z. Gao, “Self-stable 10GHz actively mode-locked fiber ring laser,” Acta Photonica Sinica, 28, 346 (1999) (in Chinese)

[1] C. Y. Lou, Y. H. Li, J. Wu, G. Q. Chang, B. Y. Wu, Y. Z. Gao, and B. K. Zhou, “Experimental study on stable 10-GHz actively mode-locked fiber ring laser,” Chinese Journal of Lasers, B8, 193 (1999)



Current group members

Wei Liu (09/01/2012—) PhD student
     
Gengji Zhou (09/01/2013—) PhD student

Qian Cao (09/01/2014—) PhD student
 
Hsiang-Yu Chung (10/01/2014—) PhD student



Current research projects

Introduction

Ultrafast optics studies the generation, manipulation, transmission, and characterization of ultrashort pulses and their innumerable applications in physics, chemistry, biology, etc. The utmost component in this field is undoubtedly lasers that are able to generate ultrashort pulses. The emergence of new lasers (e.g. thin disk lasers, fiber lasers, ceramic lasers, integrated waveguide lasers, etc.) or novel laser technology (Q-switching, mode-locking, chirped-pulse amplification, beam combining, etc.) always opens up new application fields. In return, the rapid advances in these new fields soon begin to drive new innovations in lasers to meet more challenging demands. It is this continuous back-and-forth interaction between ultrafast lasers and scientific applications that keeps ultrafast optics rapidly growing without any sign of saturation. Currently available gain media limit the wavelength coverage of solid-state ultrafast lasers in the range of 0.6-2 µm. Many applications, however, demand ultrashort pulses over a wavelength range much larger than can be provided by available lasers. In this scenario, nonlinear wavelength conversion (e.g. optical rectification, difference-frequency generation, high-harmonic generation etc.) bridges this supply-demand gap.

Our research has focused on three sub-fields of ultrafast optics—ultrafast fiber lasers, ultrafast nonlinear optics for wavelength conversion, and multiphoton microscopy; they correspond to the above-mentioned three key elements (i.e., laser sources, nonlinear manipulation of ultrashort pulses, and applications) in ultrafast optics, respectively.

1. Ultrafast fiber lasers

We strive to push the limits of ultrafast fiber laser technology and study fundamental physics in these lasers. We are particularly interested in two topics: (1) power/energy scaling of Yb-fiber laser systems—using pre-chirped managed amplification, we recently demonstrated a 100-W Yb-fiber laser delivering 60-fs pulses; and (2) investigation of noise mechanisms in fiber lasers and their suppression down to the quantum-limited level.

2. Ultrafast nonlinear optics for wavelength conversion

The fact that current frequency combs directly obtained from femtosecond lasers only cover a wavelength range from 0.6 µm to 2 µm has become an obstacle for many important applications. For example, many molecules have vibrational signatures in the range 3 to 20 µm. The wavelength range between 6 and 20 µm, in particular, has been known as the fingerprint region. Spectroscopic information of these vibrational bands reveals the molecular structure and, in turn, identifies the ingredients of the sample under test. This is of particular importance for the detection of explosives and biochemical agents. In this scenario, a high power, tunable mid-IR frequency comb is highly desired from the viewpoint of rapid high-resolution sensing.

In the time domain, ultrafast lasers provide a train of femtosecond pulses for time-resolved ultrafast spectroscopy. The time-resolved measurements of novel quantum materials (e.g., topological insulators, graphene, and high-temperature superconductors) need novel ultrafast laser sources—for example, high-power femtosecond lasers in the wavelength range of mid-infrared and low noise ultrafast lasers at visible and ultraviolet range.

We employ ultrafast nonlinear optics and high-power fiber laser technology to implement a multi-wavelength laser platform, which allows us to discover interesting ultrafast dynamics and nonlinear optical properties of the quantum materials.


3. Multiphoton microscopy

Multiphoton microscopy (MPM) has been widely used in biomedical imaging due to its unique features such as capability of optical sectioning, various imaging contrast mechanisms, and larger penetration depth in tissue imaging. The success of MPM is largely driven by the invention of the Ti:sapphire laser, which still remains the main workhorse for MPM. Ti:sapphire lasers provide a broad tuning range from 690 to 1100 nm and can excite a wide range of important fluorophores via two-photon absorption.

Our research in this subject includes two subjects: (1) development of fiber laser enabled femtosecond sources for MPM and (2) integration of novel optical detection methods with current MPM to improve sensitivity and penetration depth.