Giving to CREOL CREOL, The College of Optics & Photonics

Student of the Year

2018 Alex Sincore Hossein Hodaei
2 µm Fiber Lasers: Power scaling concepts and challenges
Fiber lasers have experienced explosive growth in the past decades, with 1 µm Ytterbium- doped lasers holding >13 % of the laser market. Fiber lasers operating at longer wavelengths, specifically 2 µm Thulium-doped lasers, are experiencing a similar growth in system performance. However, the power scaling challenges faced at 1 µm are inherently different at 2 µm. The two major limitations are high thermal loads and nonlinear effects. To address the first issue, we propose in-band pumping which substantially reduces the quantum defect. We have demonstrated >90% efficient 2 µm fiber lasers with plans to scale over 100 W. As for nonlinear effects, there is a lack of data identifying which nonlinearities limit 2 µm fiber lasers. We address this by investigating nonlinear thresholds with a variable spectral bandwidth, nanosecond pulsed fiber laser. We determine that stimulated Brillouin scattering limits narrow linewidth 2 µm sources. On the other hand, modulation instability limits broader linewidth 2 µm sources, which is not found at 1 µm. Overall, with this knowledge and proper system design, Thulium-doped fibers can continue to grow and provide high power systems for emerging applications. (see event announcement).
2017 Hossein Hodaei Hossein Hodaei
Novel photonic resonant arrangements using non-Hermitian Exceptional Points
In recent years, non-Hermitian degeneracies, also known as exceptional points (EPs), have emerged as a new paradigm for engineering the response of optical systems. Among many different non-conservative photonic configurations, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this talk, I will show how the intriguing properties of exceptional points that are arising in judiciously designed parity-time-symmetric systems can be utilized to address two of the long standing challenges in the field of integrated photonics: enforcing single mode lasing in intrinsically multimode cavities, and enhancing sensitivity of micro-resonators. (see event announcement).
2016 Cheonha Jeon Cheonha Jeon
Fundamental Studies of Ultrashort Laser Pulse Interaction with Aerosols
Delivering high intensity ultrashort laser pulses over long distances to irradiate targets has gained interest for various applications since the discovery of a laser filament. Laser filamentation in air produces a cylindrically symmetric self-channeled high intensity beam (~ 5 x 1013 W/cm2) generated by the dynamic balance between the Kerr self-focusing, self-generated plasma defocusing and diffraction. To efficiently deliver this high intensity diffraction-free beam over long distances in the atmosphere, there is a need to understand the changes in the characteristics of the laser beam as it interacts with obstacles present in air such as microscopic dust particles and aerosols. In this talk, I will present a quantitative approach to measure the energy dissipated by an ultrashort filamenting laser pulse during its interaction with a single aerosol and the subsequent effects on both the laser pulse and the aerosol. In addition to this, the impact of the droplet’s position along the radial and longitudinal axes of the beam on its characteristics will also be discussed, leading to the study of filament propagation through multiple aerosols such as fogs and clouds. (see event announcement).
2015 Jeffrey Chiles Jeffrey Chiles
Hybrid Integrated Photonic Platforms and Devices
The field of integrated optics has seen vast growth since its beginnings decades ago. The promise of mass-manufacturable, compact, and reliable systems has driven much of this growth. The use of silicon as an optical platform has been established for several decades, the silicon-on-insulator (SOI) platform being the most popular. For the pursuit of integrated photonics in the mid-infrared (3-8 μm), however, the SOI platform is inadequate due to the oxide-induced absorption and the poor performance of free carrier modulation in this regime. Motivated by these shortfalls, I conceived of and developed solutions to these problems, in the form of two new platforms. The first is the all-silicon-optical-platform (ASOP) which offers ultra-broad optical transparency from 1.2 to 8.5 μm. The second is silicon-on-lithium niobate (SiLN), the first silicon-based mid-infrared compatible platform to exhibit second-order nonlinearity. I will present the results of recently demonstated mid-infrared optical modulators built on SiLN technology. (see event announcement).
2014 Clémence Jollivet Clémence Jollivet
Specialty Fibers for Novel Fiber Lasers and Devices
Designs of novel specialty fibers are finely tuned to enable transmission of light carrying specific properties (wavelength, profile, polarization, dispersion, etc.), opening the route towards potential applications such as average or peak power scaling of fiber laser, beam shaping, optical sensing, and telecommunications.

As the complexity of the fiber inner structure increases, the fabrication process becomes critical. Therefore, there is a strong demand for advanced experimental diagnostics enabling to characterize in detail the transmitted light. Here, a powerful mode analysis technique, directly inspired from the spatially and spectrally resolved imaging experiment (S2 imaging), has been employed to successfully interrogate several specialty fiber prototypes. A few striking examples are presented where targeted applications are proposed according to the measured mode content.

Furthermore, challenges related to the monolithic integration of active specialty fibers with commercially available fiber technologies are highlighted and tackled via two examples of fiber laser systems: one employing an active large-mode photonic crystal fiber and a second using an active seven-core fiber (see event announcement).
2013 Neng Bai Neng Bai
Mode-division multiplexed optical communication in few-mode fibers
As a promising candidate to break the single-mode fiber capacity limit, mode-division multiplexing (MDM) explores the spatial dimension to increase transmission capacity in fiber-optic communication. Two linear impairments, namely loss and multimode interference, present fundamental challenges to implement MDM. This talk will describe methods to resolve those two issues. To compensate loss of different modes, we propose multimode EDFAs with reconfigurable multimode pumps. To de-multiplex signals subject to multimode interference in the MDM, adaptive frequency-domain equalization (FDE) has been proposed and investigated. The multimode EDFA and the FDE algorithm have been used to demonstrate 30 terabit/s MDM-WDM transmission in a few-mode fiber. (see event announcement).
2012 Nazanin Hoghooghi Nazanin Hoghooghi
Linear modulation, direct demodulation and channel filtering using injection-locked semiconductor lasers
A novel linear interferometric intensity modulator based on an injection-locked laser as an arcsine phase modulator, is described. Spur-free dynamic range of ~130 dB.Hz2/3 is achieved in an analog link employing this modulator. Also, direct demodulation and channel filtering of phase-modulated optical signals using and injection-locked semiconductor laser is presented. (see event announcement).
2011 Dimitrios Mandridis Dimitrios Mandridis
A low noise Theta laser with an intra-cavity Fabry-Pérot etalon and high precision etalon characterization
The talk will present an extensive investigation of a chirped-pulse semiconductor-based Theta cavity design laser with an intra-cavity Fabry-Pérot etalon operating at 100 MHz repetition rate. A fiberized Fabry-Pérot periodic filter inserted within the Theta laser cavity mitigates the contribution of the supermode noise to the pulse-to-pulse energy variance by >10 times. Long-term stability is attained by referencing the cavity length to the etalon using a modified intra-cavity Hänsch-Couillaud locking scheme. Moreover, the high precision characterization of the etalon used in the Theta laser will be presented. A narrow linewidth laser source is used in conjunction with an acousto-optic modulator resulting in 10 parts per billion precision. The Theta laser can be used in photonic ADC and optical coherence tomography among other applications. (see event announcement).
2010 David Haefner David Haefner
Spin Transfer and Power Flow at Subwavelength Scales
Angular momentum is exchanged when an electromagnetic wave encounters a scattering medium. We dem-onstrate that the spin-orbit interaction in scattering from a spherically symmetric potentials results in a spiral flow of energy in the near-field and intermediate zones. We will show how such a power flow can be observed and will discuss some consequences for field mediated interactions at subwavelength scales. As an, we will discuss the emergence of a new kind of "optical matter" where nonconservative forces and torques determine kinematic properties, which are strongly coupled to the polarization state of the exciting radiation. (see event announcement).
2009 Oleksandr Savchyn
Oleksander Savchyn
Sensitizers of erbium in silicon-rich SiO2: nanocrystals or luminescence centers?
The implementation of silicon photonics requires the development of a compact silicon-compatible light source. One of the possible routes for its realization is to use the emission from optical centers incorporated into silicon-based matrices and sensitized with dopants. It has long been thought that silicon nanocrystals can be used as efficient and dominant sensitizers of erbium in silicon-doped SiO2. In the current presentation it will be shown that the indirect excitation of erbium in this material does not require the presence of silicon nanocrystals. This conclusion clarifies a number of previously unexplained results and opens new opportunities in the field of silicon photonics (see event announcement).
2008 Georgios A. Siviloglou
Georgios A. Siviloglou
Observation of Accelerating Airy Beams
We report the first observation of Airy optical beams. This intriguing class of wave packets, initially predicted by Berry and Balazs in 1979, has been realized in both one- and two-dimensional configurations. As demonstrated in our experiments, these Airy beams can remain diffraction-free over long distances while they tend to freely accelerate during propagation (see event announcement).
2007 Ying Zhou
Ying Zhou
High performance cholesteric liquid crystal lasers
(see event announcement).
2006 Erwan Baleine
Erwan Baleine
Surface pinning effect of polymer-dispersed liquid crystal and its applications
(see event announcement).
Jeremy D. Ellis 2005 Jeremy D. Ellis
Anne Janet Milliez 2004 Anne Janet Milliez
Michael Mielke 2003 Michael Mielke
Gabriel Popescu Sergey Polyakov 2002 Gabriel Popescu & Sergey Polyakov
2001 Irina Puscasu
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