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Quantum wells in Nanowires for Optoelectronic Applications: Materials and Devices - Dr. Lan Fu6/15/2022
Thursday, June 23rd, 2:00 pm (PDT) -- Burgers from Kyle’s! Hosted in-person in Henley Hall 1010 Abstract – III-V compound semiconductor nanowires (NWs) have drawn much attention as nanoscale building blocks for integrated photonics/optoelectronics due to their nanoscale size, excellent optical properties and effectiveness in strain relaxation enabling the monolithic growth on lattice-mismatched substrates. In particular, NWs grown by selective area epitaxy technique have many advantages such as controllability of their size and position, high uniformity in diameter and length, as well as complementary metal-oxide-semiconductor (CMOS) process compatibility, facilitating their integration with other electronic devices. With suitable wavelength ranging from 1.3 to 1.6 μm and lattice match of constituent materials, InGaAs/InP quantum well (QW) has been being widely used for optical communication devices. However there has been limited understanding on the growth of InGaAs/InP QW in nanowire architecture and their application for optoelectronic devices such as lasers/LEDs and photodetectors. In this work, we present the study of the selective area epitaxy growth of InGaAs/InP multi-QW NW array by metalorganic chemical vapour deposition (MOCVD) technique, and the demonstration of nanowire LEDs/lasers and photodetectors with an investigation of their strong geometry related device properties by both numerical simulation and optoelectronic characterizations. Bio – Lan Fu received her PhD degree from the Australia National University (ANU) in 2001 and is currently a Full Professor at the Research School of Physics, ANU. Prof. Lan Fu was the recipient of the IEEE Photonic Society Graduate Student Fellowship (2000), Australian Research Council (ARC) Postdoctoral Fellowship (2002), ARF/QEII Fellowship (2005) and Future Fellowship (2012). Professor Fu is a senior member of IEEE, IEEE/Photonics and Electron Devices Societies and was the past chair of the Photonics Society, Electron Devices Society and Nanotechnology Council Chapters of the IEEE ACT section. She is the Chair of IEEE Nanotechnology Council Chapters & Regional Activities Committee, Associate Editor of IEEE Photonics Journal, and member of Editorial Board of Opto-Electronic Advances. She also the current member of the Australian Academy of Science National Committee on Materials Science and Engineering, Secretary of the Executive Committee of Australian Materials Research Society (AMRS), and Australian Research Council College of Experts. Professor Lan Fu’s main research interests include design, fabrication and integration of optoelectronic devices (LEDs, lasers, photodetectors and solar cells) based on low-dimensional III-V compound semiconductor structures including quantum wells, self-assembled quantum dots and nanowires grown by metal-organic chemical vapour deposition (MOCVD). Li, Z. Y., Tan, H. H., Jagadish, C., Fu, L., Adv. Mater. Technol. 2018, 3, 1800005. https://doi.org/10.1002/admt.201800005 
Friday, May 13th, 1:00 pm (PST) -- pizza provided! Hosted in-person in ESB 1001 and via Zoom Bio – Alexa Hudnut is an Optical Systems Engineer at Illumina in San Diego. Her research background is true to a Biomedical Engineer – a little bit of everything. She started her research in molecular biology and gene editing and then worked her way to instrumentation design and optics. She graduated with a PhD in Biomedical Engineering from the University of Southern California in 2018. She is most passionate about creating medical devices that leverage Optics and Materials Science for an intentionally sustainable future. Abstract – Illumina’s mission is to improve human health by unlocking the power of the genome. This translates to efforts such as tracking COVID variants, determining your dog’s breed, population genomics, and everything in between. Next generation sequencing (NGS) relies heavily on epifluorescence microscopy as the backbone of instrumentation. As we look toward the future of gene sequencing, it will become more prevalent as an in vitro diagnostic (IVD). To improve the clinical workflow, increased throughput is necessary for quicker turnaround times. These improvements are being driven by innovations such as structured illumination, multiplexing, image processing, and nanofabrication.
 Group photo of the QIS 2022 attendees outside Henley Hall The Photonics Society collaborated with the UCSB NSF Quantum Foundry to host industry partners and students for an in-person showcase event on April 22, 2022. The goal of the Quantum Industry Showcase (QIS) is to connect industry partners with the graduate students and postdocs working in quantum materials and technologies. With opportunities to ask questions and chat in-person, the event helps to foster discussion, mentoring, and recruitment. The event began with a keynote given by Kevin Roche of IBM followed by presentations from Hewlett Packard Enterprise, Cisco, and HRL. Attendees were able to ask questions and chat with industry partners during a panel session and a networking lunch. In the afternoon, representatives from Honeywell, Quantum Machines, and Quantinuum gave presentations. The event concluded after giving students the opportunity to showcase their work at a poster session. The Quantum Industry Showcase was attended by industry partners from Thorlabs, Quantinuum, Oxford Instruments NanoScience, Bleximo, HRL, Hewlett Packard Enterprise, IBM, Quantum Machines, Cisco, Honeywell, and Nexus Photonics. Prior to the QIS event, Thorlabs provided students with a tour of their facilities. The QIS event was sponsored in part by Oxford Instruments. For more information, visit 2022-qis.quantumfoundry.ucsb.edu 
Friday March 4th at 1:00pm PST in Henley Hall 1010 and via Zoom Pizza Provided in-person! Porous semiconducting nitrides are effectively a new class of semiconducting material, with properties distinct from the monolithic nitride layers from which devices from light emitting diodes (LEDs) to high electron mobility transistors are increasingly made. The introduction of porosity provides new opportunities to engineer a range of properties including refractive index, thermal and electrical conductivity, stiffness and piezoelectricity. Quantum structures may be created within porous architectures and novel composites may be created via the infiltration of other materials into porous nitride frameworks. A key example of the application of porous nitrides in photonics is the fabrication of high reflectivity distributed Bragg reflectors (DBRs) from alternating layers of porous and non-porous GaN. These reflectors are fabricated from epitaxial structures consisting of alternating doped and undoped layers, in which only the conductive, doped layers are electrochemically etched. Conventionally, trenches are formed using a dry-etching process, penetrating through the multilayer, and the electrochemical etch then proceeds laterally from the trench sidewalls. The need for these trenches then limits the device designs and manufacturing processes within which the resulting reflectors can be used. We have developed a novel alternative etching process, which removes the requirement for the dry-etched trenches, with etching proceeding vertically from the top surface through channels formed at naturally-occurring defects in the crystal structure of GaN. This etch process leaves an undoped top surface layer almost unaltered and suitable for further epitaxy. This new defect-based etching process provides great flexibility for the creation of a variety of sub-surface porous architectures on top of which a range of devices may be grown. Whilst DBR structures enable improved light extraction from LEDs and the formation of resonant cavities for lasers and single photon sources, recent development also suggest that thick, subs-surface porous layers may enable strain relaxation to help improve the efficiency of red microLEDs for augmented reality displays. Meanwhile, the option of filling pores in nitride layers with other materials provides new opportunities for the integration of nitrides with emerging photonic materials, such as the hybrid-perovskite semiconductors, with perovskites encapsulated in porous nitride layers demonstrating greatly improved robustness against environmental degradation.
 Join us at Henley Hall 1010 on 10/28 at 1pm! Free Pizza Provided!
Dr. Julia Majors - Master Oscillator Packaging for the Laser Interferometer Space Antenna (LISA)7/8/2021
Thursday, July 15, 10:00 - 11:00 am (PDT) 5 years after the earth-based gravitational wave observatory, LIGO, made its first detection of gravitational waves, work is already well underway in preparing for the next generation of gravitational wave observatories – in orbit around the sun. Working with NASA Goddard Space Flight Center, we are building what will be the “quietest” oscillator in (and above) the world to serve as the core light source for the interferometric system. The system is based on a non-planar ring oscillator (NPRO) model, which I will discuss along with some of the challenges that arise when developing laser systems for space applications. Student Lecture by KaiKai Liu on Milliwatt Threshold 0.5-Hz Linewidth Si3N4 Brillouin Laser5/25/2021
 Friday May 28 at 1:00 pm
 The UCSB Quantum Foundry and the UCSB Photonics Society hosted the 2021 Quantum Industry Showcase on April 22 and 23. You can watch the Keynote address and the fireside chat below. You can also find more information and presentations from the event at https://qis.quantumfoundry.ucsb.edu/. Like these videos? Watch the full QIS 2021 playlist at
https://www.youtube.com/watch?v=xulQc4G_R9w&list=PLtIKDPzlP_wMvxVLMWlnP-lP6kb7Lr29l  1:00 PM Friday, April 2nd
Friday, January 29th, 10 am (PST) Infrared detectors and imaging systems are becoming increasingly important in a diverse range of astronomic, military, and civilian applications. This field has gained significant attention while incorporating various materials and architectures into detector designs with a strong focus on applicability into clinical domains. Dr. Perera will discuss recent detector structures, and his latest work on disease detection. Biomedical applications of infrared include an exploration of an Affordable, Sensitive, Specific, User-friendly, Rapid, Equipment-free, and Deliverable (ASSURED) diagnostic regimen and testing its clinical feasibility for inflammatory bowel diseases (IBDs) and cancer screening. A study using Fourier transform infrared (FTIR) spectroscopy in attenuated total reflectance (ATR) sampling mode analyzed body fluids in order to identify reproducible, stable, and statistically significant differences in spectral signatures of the IR absorbance spectra between the control and disease samples. These results show that serum samples can be used to detect the biochemical changes induced by these diseases.
 1:00 PM Friday, January 22nd |
 Yahya Mohtashami Schuller group ECE Dept, UCSB |
In this talk, we show that we can increase the light extraction efficiency of, impart directionality upon, collimate, and focus the spontaneous emission from InGaN/GaN quantum wells, using phased-array metasurfaces. |
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Strong THz laser fields can explore non-linear, non-equilibrium phenomena in matter. The talk will focus on photons emitted by electron/hole re-collisions, and how the polarization of these photons carries information about the semiconductor. |
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Friday, October 23rd, 11 am (PDT) via Zoom
Dr. Christian Reimer is a physicist and entrepreneur working in the fields of nonlinear optics, integrated photonics and quantum optics. He received graduate degrees from the Karlsruhe Institute of Technology in Germany, Heriot-Watt University in Scotland, and the National Institute of Scientific Research in Canada. He then worked as a postdoctoral fellow at Harvard University, before becoming Co-Founder and Head of Product of HyperLight Corporation. HyperLight, a Venture-Capital funded start-up out of Harvard University, is specialized on integrated lithium niobate technologies for ultra-high performance photonic solutions.
In the scientific part of his talk, Christian will introduce the field of integrated photonics based on thin-film lithium niobate, with a focus on electro-optic applications, as well as recent progress on transforming the field from chip-based proof-of-concept realizations for wafer-scale production. In the professional development section, he will then share his experience transitioning from academia to a start-up company. He will talk about differences and similarities in the work environment, what to expect in terms of tasks and responsibilities, and explain how salaries at start-ups can include combinations of equity and incentives.
In the scientific part of his talk, Christian will introduce the field of integrated photonics based on thin-film lithium niobate, with a focus on electro-optic applications, as well as recent progress on transforming the field from chip-based proof-of-concept realizations for wafer-scale production. In the professional development section, he will then share his experience transitioning from academia to a start-up company. He will talk about differences and similarities in the work environment, what to expect in terms of tasks and responsibilities, and explain how salaries at start-ups can include combinations of equity and incentives.
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Images from hyperlightcorp.com
 | On Henley Hall Prof. John Bowers |  |
Friday, Oct. 16th, 4 pm (PDT) via Zoom
Henley Hall will hold state-of-the-art research facilities for developing energy-efficient technologies. Prof. Bowers will present the research capabilities and expected research ramp-up timeline for the new building.
Thursday, Oct. 8, 1-2 pm (PDT) via Zoom
Meeting ID: 819 4601 6935, Password: 597044
Meeting ID: 819 4601 6935, Password: 597044
Entanglement and encoding in discrete frequency bins – a quantum analogue of wavelength-division multiplexing – represents a relatively new degree of freedom for quantum information with photons. Potential advantages include generation of high-dimensional units of quantum information called qudits, which can carry multiple qubits per photon; robust transmission over fiber; frequency parallelism and routing; and compatibility with on-chip implementations, as well as hyperentanglement with other photonic degrees of freedom. In this talk I first give an overview of manipulating and measuring quantum states encoded and entangled in the photonic frequency degree of freedom. I will then discuss our recent experiments that focus on high-dimensional entanglement and mixing of multiple frequency bins in a single operation, going well beyond nearest neighbor “interactions.
Tuesday, September 8th, 10 am (PDT) via Zoom
Meeting ID: 978 3569 2970 Passcode: 468555
Meeting ID: 978 3569 2970 Passcode: 468555
Infectious diseases and water are some of the greatest, most urgent challenges of the 21st century. III-nitride ultraviolet (UV) light sources, including light emitting diodes (LEDs) and lasers, are the only alternative technology to replace conventional power-hungry, hazardous mercury lamps for disinfection and water purification. Recent studies showed that AlGaN-based UV-C LEDs can readily shred genetic material of viruses and bacterial and achieve 99.9% sterilization of SARS-COV-2. In this talk, I will present the recent advances of AlGaN and BN nanostructures and heterostructures and their applications in UV optoelectronics, including the first demonstration of mid and deep UV laser diodes and tunnel junction UV-C LEDs with significantly improved performance. The recent development of far-UV-C LEDs, in the wavelength range of 207-222 nm, will also be presented, which has shown to be faster and far more effective than traditional UV-C light (~265 nm) in preventing the transmission of microbial diseases, while causing virtually no harm to mammalian skin or eye.
  Schematic for the cross-section of a TACIT mixer (right); Optical image of a TACIT mixer with an SEM image of the active region (top) | Terahertz Heterodyne Detector Based on the Intersubband Transition of a GaAs/AlGaAs Quantum WellWe are developing a new type of THz heterodyne detector based on a high-mobility 2-dimensional electron gas (2DEG) in a GaAs/AlGaAs quantum well for spectroscopic applications in deep-space and planetary missions. Named as Tunable Antenna-Coupled Intersubband Terahertz (TACIT) mixer, the detector is a four-terminal hot-electron bolometer (HEB) mixer that uses intersubband transition for efficient absorption of THz radiation in a 2DEG. The dual gate structure of TACIT mixers, necessary for the precise control of the intersubband absorption characteristics, enables a high coupling efficiency at THz frequencies and tunability in the detection frequency, but also poses challenges in the fabrication, modelling, and operation of the device. In this talk, I will discuss our recent experimental results with a prototype TACIT mixer that we have fabricated with a flip-chip process that enables dual-side processing of a sub-micron thick quantum well membrane.  |
Wednesday, May 20, 2020, 1 p.m.
Sustainability applied to networking is about treating professional support and assistance like a resource, and creating more of it than you take. Dr. Willis will discuss principles and applications of sustainable professional networking, and how to use it to generate success through mutually beneficial professional relationships. She will also discuss her own career path, citing examples that illustrate the value of sustainable networking.
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Engineering robust solid-state quantum systems is amongst the most pressing challenges to realize scalable quantum photonic circuitry. While several 3D systems (such as diamond or silicon carbide) have been thoroughly studied, solid state emitters in two dimensional (2D) materials are still in their infancy. In this presentation I will discuss single defects in an emerging 2D material – hexagonal boron nitride (hBN), that is promising as qubits for quantum photonic applications. In particular, I will focus on ways to engineer these defects deterministically using either chemical vapour deposition growth or ion implantation, and show results on strain tuning of these ultra-bright quantum emitters. I will then highlight promising avenues to integrate the single defects with photonic cavities, as a first step towards integrated quantum photonics with 2D materials. I will summarize by outlining challenges and promising directions in the field of quantum emitters and nanophotonics with 2D materials.
Watch the recorded lecture from April 23, 2020:
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Founded in 2018, Nexus Photonics has developed integrated photonics ready to scale. Smaller, lighter and faster, their platform outperforms industry benchmarks, and operates in an ultra-broadband wavelength range from ultraviolet to infrared to support a wide breadth of practical applications.
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