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Bowers JE, Paterson AH. Chromosome number is key to longevity of polyploid lineages. THE NEW PHYTOLOGIST 2021; 231:19-28. [PMID: 33772797 DOI: 10.1111/nph.17361] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Polyploidy is ubiquitous and often recursive in plant lineages, most frequently resulting in extinction but occasionally associated with great evolutionary success. However, instead of chromosome numbers exponentially increasing due to recurrent polyploidy, most angiosperm species have fewer than 14 chromosome pairs. Following genome duplication, diploidisation can render one copy of essential genes nonfunctional without fitness cost. In isolated subpopulations, alternate (homoeologous) gene copies can be lost, creating incompatibilities that reduce fitness of hybrids between subpopulations, constraining exchange of favourable genetic changes and reducing species fitness. When multiple sets of incompatible genes are genetically linked, their deleterious effects are not independent. The effective number of independently acting sets of incompatible loci in hybrids is limited by chromosome number and recombination. Therefore, species with many chromosomes are subject to a higher fitness penalty during diploidisation. Karyotypic changes, especially fusions, that reduce gene flow are normally fitness disadvantages, but during the diploidisation process, can increase fitness by reducing mixing of differentially diploidised alleles. Fitness penalties caused by diploidisation favour accelerated karyotypic change, with each change increasing barriers to gene flow, contributing to speciation. Lower chromosome numbers and increased chromosome fusions confer advantages to surviving the diploidisation process following polyploid formation, by independent mechanisms.
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Jin W, Feshali A, Paniccia M, Bowers JE. Seamless multi-reticle photonics. OPTICS LETTERS 2021; 46:2984-2987. [PMID: 34129590 DOI: 10.1364/ol.427289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 05/26/2021] [Indexed: 06/12/2023]
Abstract
While Moore's law predicted shrinking transistors would enable exponential scaling of electronic circuits, the footprint of photonic components is limited by the wavelength of light. Thus, future high-complexity photonic integrated circuits (PICs) such as petabit-per-second transceivers, thousand-channel switches, and photonic quantum computers will require more area than a single reticle provides. In our novel approach, we overlay and widen waveguides in adjacent reticles to stitch a smooth transition between misaligned exposures. In SiN waveguides, we measure ultralow loss of 0.0004 dB per stitch, and produce a stitched delay line 23 m in length. We extend the design to silicon channel waveguides, and predict 50-fold lower loss or 50-fold smaller footprint versus a multimode-waveguide-based method. Our approach enables large-scale PICs to scale seamlessly beyond the single-reticle limit.
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Boes A, Nguyen TG, Chang L, Bowers JE, Ren G, Mitchell A. Integrated photonic high extinction short and long pass filters based on lateral leakage. OPTICS EXPRESS 2021; 29:18905-18914. [PMID: 34154136 DOI: 10.1364/oe.426442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
In this contribution we present a new approach to achieve high extinction short and long pass wavelength filters in the integrated photonic platform of lithium niobate on insulator. The filtering of unwanted wavelengths is achieved by employing lateral leakage and is related to the bound state in the continuum phenomenon. We show that it is possible to control the filter edge wavelength by adjusting the waveguide dimensions and that an extinction of hundreds of dB/cm is readily achievable. This enabled us to design a pump wavelength suppression of more than 100 dB in a 3.5 mm long waveguide, which is essential for on-chip integration of quantum-correlated photon pair sources. These findings pave the way to integrate multi wavelength experiments on chip for the next generation of photonic integrated circuits.
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Steindl P, Snijders H, Westra G, Hissink E, Iakovlev K, Polla S, Frey JA, Norman J, Gossard AC, Bowers JE, Bouwmeester D, Löffler W. Artificial Coherent States of Light by Multiphoton Interference in a Single-Photon Stream. PHYSICAL REVIEW LETTERS 2021; 126:143601. [PMID: 33891441 DOI: 10.1103/physrevlett.126.143601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/05/2021] [Indexed: 06/12/2023]
Abstract
Coherent optical states consist of a quantum superposition of different photon number (Fock) states, but because they do not form an orthogonal basis, no photon number states can be obtained from it by linear optics. Here we demonstrate the reverse, by manipulating a random continuous single-photon stream using quantum interference in an optical Sagnac loop, we create engineered quantum states of light with tunable photon statistics, including approximate weak coherent states. We demonstrate this experimentally using a true single-photon stream produced by a semiconductor quantum dot in an optical microcavity, and show that we can obtain light with g^{(2)}(0)→1 in agreement with our theory, which can only be explained by quantum interference of at least 3 photons. The produced artificial light states are, however, much more complex than coherent states, containing quantum entanglement of photons, making them a resource for multiphoton entanglement.
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Wan Y, Norman J, Liu S, Liu A, Bowers JE. Quantum Dot Lasers and Amplifiers on Silicon: Recent Advances and Future Developments. IEEE NANOTECHNOLOGY MAGAZINE 2021. [DOI: 10.1109/mnano.2020.3048094] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Chang L, Xie W, Shu H, Yang QF, Shen B, Boes A, Peters JD, Jin W, Xiang C, Liu S, Moille G, Yu SP, Wang X, Srinivasan K, Papp SB, Vahala K, Bowers JE. Author Correction: Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators. Nat Commun 2021; 12:1803. [PMID: 33727533 PMCID: PMC7966803 DOI: 10.1038/s41467-021-22031-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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32
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Khope ASP, Helkey R, Liu S, Khope S, Alferness RC, Saleh AAM, Bowers JE. Scalable multicast hybrid broadband-crossbar wavelength selective switch: proposal and analysis. OPTICS LETTERS 2021; 46:448-451. [PMID: 33449050 DOI: 10.1364/ol.412242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
In this Letter, we present a new hybrid broadband-crossbar switching network that can switch multiple wavelengths on demand and can also multicast. This switch fabric is an improvement over our previous design in both switch footprint and power consumption, as it reduces the number of switching elements by approximately 50%. We compare the switch loss and crosstalk with that of a multiwavelength selective crossbar switch. We also comment on fabrication tolerance of second-order ring resonators based on experimental results of 64 second-order ring resonators, and more than 250 heaters.
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33
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Liang D, E. Bowers J. Recent Progress in Heterogeneous III-V-on-Silicon Photonic Integration. ACTA ACUST UNITED AC 2021. [DOI: 10.37188/lam.2021.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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34
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Xie W, Chang L, Shu H, Norman JC, Peters JD, Wang X, Bowers JE. Ultrahigh-Q AlGaAs-on-insulator microresonators for integrated nonlinear photonics. OPTICS EXPRESS 2020; 28:32894-32906. [PMID: 33114964 DOI: 10.1364/oe.405343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
Aluminum gallium arsenide (AlGaAs) and related III-V semiconductors have excellent optoelectronic properties. They also possess strong material nonlinearity as well as high refractive indices. In view of these properties, AlGaAs is a promising candidate for integrated photonics, including both linear and nonlinear devices, passive and active devices, and associated applications. Low propagation loss is essential for integrated photonics, particularly in nonlinear applications. However, achieving low-loss and high-confinement AlGaAs photonic integrated circuits poses a challenge. Here we show an effective reduction of surface-roughness-induced scattering loss in fully etched high-confinement AlGaAs-on-insulator nanowaveguides by using a heterogeneous wafer-bonding approach and optimizing fabrication techniques. We demonstrate ultrahigh-quality AlGaAs microring resonators and realize quality factors up to 3.52 × 106 and finesses as high as 1.4 × 104. We also show ultra-efficient frequency comb generations in those resonators and achieve record-low threshold powers on the order of ∼20 µW and ∼120 µW for the resonators with 1 THz and 90 GHz free-spectral ranges, respectively. Our result paves the way for the implementation of AlGaAs as a novel integrated material platform specifically for nonlinear photonics and opens a new window for chip-based efficiency-demanding practical applications.
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Khope ASP, Liu S, Zhang Z, Netherton AM, Hwang RL, Wissing A, Perez J, Tang F, Schow C, Helkey R, Alferness RC, Saleh AAM, Bowers JE. 2 λ switch. OPTICS LETTERS 2020; 45:5340-5343. [PMID: 33001889 DOI: 10.1364/ol.402241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/08/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate an elastic multi-wavelength selective switch with up to two wavelength switching capability per crosspoint. We fabricated the switch in a silicon photonics foundry and demonstrated a 17 nm tuning range for ring resonators, with a mean path loss of 2.43 dB. This is a 70% reduction in path loss as compared to previous generations, and we demonstrate a high-speed pulse-amplitude-modulation-4 transmission at 111 Gbps through different paths of the switch.
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Dong B, de Labriolle XC, Liu S, Dumont M, Huang H, Duan J, Norman JC, Bowers JE, Grillot F. 1.3-µm passively mode-locked quantum dot lasers epitaxially grown on silicon: gain properties and optical feedback stabilization. JPHYS PHOTONICS 2020. [DOI: 10.1088/2515-7647/aba5a6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
This work reports on an investigation of the optical feedback in an InAs/InGaAs passively mode-locked quantum dot (QD) laser epitaxially grown on silicon. Under the stably-resonant optical feedback condition, experiments demonstrate that the radio-frequency linewidth is narrowed whatever the bias voltage applied on the saturable absorber (SA) is; on the other hand, the effective linewidth enhancement factor of the device increases with the reverse bias voltage on the SA, hence it is observed that such an increase influences the mode-locking dynamic and the stability of device under optical feedback. This work gives insights for stabilizing epitaxial QD mode-locked lasers on silicon which is meaningful for their applications in future large-scale silicon electronic and photonic applications requiring low power consumption as well as for high-speed photonic analog-to-digital conversion, intrachip/interchip optical clock distribution and recovery.
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Stern L, Zhang W, Chang L, Guo J, Xiang C, Tran MA, Huang D, Peters JD, Kinghorn D, Bowers JE, Papp SB. Ultra-precise optical-frequency stabilization with heterogeneous III-V/Si lasers. OPTICS LETTERS 2020; 45:5275-5278. [PMID: 32932510 DOI: 10.1364/ol.398845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
The demand for low-noise, continuous-wave, frequency-tunable lasers based on semiconductor integrated photonics has advanced in support of numerous applications. In particular, an important goal is to achieve a narrow spectral linewidth, commensurate with bulk-optic or fiber-optic laser platforms. Here we report on laser-frequency-stabilization experiments with a heterogeneously integrated III/V-Si widely tunable laser and a high-finesse, thermal-noise-limited photonic resonator. This hybrid architecture offers a chip-scale optical-frequency reference with an integrated linewidth of 60 Hz and a fractional frequency stability of 2.5×10-13 at 1 s integration time. We explore the potential for stabilization with respect to a resonator with lower thermal noise by characterizing laser-noise contributions such as residual amplitude modulation and photodetection noise. Widely tunable, compact and integrated, cost-effective, stable, and narrow-linewidth lasers are envisioned for use in various fields, including communication, spectroscopy, and metrology.
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Duan J, Zhou Y, Dong B, Huang H, Norman JC, Jung D, Zhang Z, Wang C, Bowers JE, Grillot F. Effect of p-doping on the intensity noise of epitaxial quantum dot lasers on silicon. OPTICS LETTERS 2020; 45:4887-4890. [PMID: 32870883 DOI: 10.1364/ol.395499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
This work experimentally investigates the impact of p-doping on the relative intensity noise (RIN) properties and subsequently on the modulation properties of semiconductor quantum dot (QD) lasers epitaxially grown on silicon. Owing to the low threading dislocation density and the p-modulation doped GaAs barrier layer in the active region, the RIN level is found very stable with temperature with a minimum value of -150dB/Hz. The dynamical features extracted from the RIN spectra show that p-doping between zero and 20 holes/dot strongly modifies the modulation properties and gain nonlinearities through increased internal losses in the active region and thereby hinders the maximum achievable bandwidth. Overall, this Letter is important for designing future high-speed and low-noise QD devices integrated in future photonic integrated circuits.
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Qin J, Shu H, Chang L, Xie W, Tao Y, Jin M, Wang X, Bowers JE. On-chip high-efficiency wavelength multicasting of PAM3/PAM4 signals using low-loss AlGaAs-on-insulator nanowaveguides. OPTICS LETTERS 2020; 45:4539-4542. [PMID: 32797003 DOI: 10.1364/ol.398777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/10/2020] [Indexed: 06/11/2023]
Abstract
Nonlinear optics-based optical signal processing (OSP) could potentially increase network flexibility because of its transparency, tunability, and large bandwidth. A low-loss, high nonlinearity, and compact integrated material platform is always the pursuit of OSP. In this Letter, a high-efficiency, one-to-six wavelength multicasting of 10 Gbaud pulse-amplitude modulation (PAM3/PAM4) signals using a 6 cm long Al0.2Ga0.8As-on-insulator nanowaveguide is experimentally demonstrated for the first time, to the best of our knowledge. The low-loss, combined with the high nonlinear coefficient of the AlGaAsOI platform, enables us to achieve -11.2dB average conversion efficiency clear eye diagrams and <2.1dB power penalty at KP4-forward error correction threshold (2.4×10-4) for all the output PAM3/PAM4 multicasting channels. This result points to a new generation of nonlinear OSP photonic integrated circuits.
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Malik A, Spott A, Wang Y, Stanton EJ, Peters J, Bowers JE. High resolution, high channel count mid-infrared arrayed waveguide gratings in silicon. OPTICS LETTERS 2020; 45:4551-4554. [PMID: 32797007 DOI: 10.1364/ol.397135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/16/2020] [Indexed: 06/11/2023]
Abstract
Arrayed waveguide gratings (AWGs) working in the 4.7 µm wavelength range are reported on silicon-on-insulator waveguides with 1500 nm thick silicon and 2 µm thick buried oxide layers. For eight channel devices, three different channel spacings (200 GHz, 100 GHz, and 50 GHz) with cross talk levels of -32.31dB, -31.87dB, and -27.28dB and insertion loss levels of -1.43dB, -4.2dB, and -2.3dB, respectively, are demonstrated. Fourteen channel AWGs with 170 GHz channel spacing and 16 channel AWGs with 87 GHz channel spacing are shown to have a cross talk value of -21.67dB and -24.30dB and insertion loss value of -4.2dB and -3.8dB, respectively. Two AWGs with 10 nm difference in channel peak are designed, and the measurements show a 9.3 nm difference. The transmission spectrum shift as a function of temperature is found to be 0.22 nm/°C.
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Chow YC, Lee C, Wong MS, Wu YR, Nakamura S, DenBaars SP, Bowers JE, Speck JS. Dependence of carrier escape lifetimes on quantum barrier thickness in InGaN/GaN multiple quantum well photodetectors. OPTICS EXPRESS 2020; 28:23796-23805. [PMID: 32752371 DOI: 10.1364/oe.399924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/11/2020] [Indexed: 06/11/2023]
Abstract
We reported significant improvements in device speed by reducing the quantum barrier (QB) thicknesses in the InGaN/GaN multiple quantum well (MQW) photodetectors (PDs). A 3-dB bandwidth of 700 MHz was achieved with a reverse bias of -6 V. Carrier escape lifetimes due to carrier trapping in the quantum wells (QWs) were obtained from both simulation and experimental fitting, identifying carrier trapping as the major speed limiting factor in the InGaN/GaN MQW PDs.
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Xiang C, Jin W, Guo J, Williams C, Netherton AM, Chang L, Morton PA, Bowers JE. Effects of nonlinear loss in high-Q Si ring resonators for narrow-linewidth III-V/Si heterogeneously integrated tunable lasers. OPTICS EXPRESS 2020; 28:19926-19936. [PMID: 32680062 DOI: 10.1364/oe.394491] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
High-Q Si ring resonators play an important role in the development of widely tunable heterogeneously integrated lasers. However, while a high Q-factor (Q > 1 million) is important for ring resonators in a laser cavity, the parasitic high-power density in a Si resonator can deteriorate the laser performance at high power levels due to nonlinear loss. Here, we experimentally show that this detrimental effect can happen at moderate power levels (a few milliwatts) where typical heterogeneously integrated lasers work. We further compare different ring resonators, including extended Si ring resonators and Si3N4 ring resonators and provide practical approaches to minimize this effect. Our results provide explanations and guidelines for high-Q ring resonator designs in heterogeneously integrated tunable lasers, and they are also applicable for hybrid integrated butt-coupled lasers.
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Jin W, John DD, Bauters JF, Bosch T, Thibeault BJ, Bowers JE. Deuterated silicon dioxide for heterogeneous integration of ultra-low-loss waveguides. OPTICS LETTERS 2020; 45:3340-3343. [PMID: 32538978 DOI: 10.1364/ol.394121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Ultra-low-loss waveguide fabrication typically requires high-temperature annealing beyond 1000°C to reduce the hydrogen content in deposited dielectric films. However, realizing the full potential of an ultra-low loss will require the integration of active materials that cannot tolerate high temperature. Uniting ultra-low-loss waveguides with on-chip sources, modulators, and detectors will require a low-temperature, low-loss dielectric to serve as a passivation and spacer layers for complex fabrication processes. We report a 250°C deuterated silicon dioxide film for top cladding in ultra-low-loss waveguides. Using multiple techniques, we measure propagation loss below 12 dB/m for the entire 1200-1650 nm range and top-cladding material absorption below 1 dB/m in the S, C, and L bands.
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Li C, Zhang M, Bowers JE, Dai D. Ultra-broadband polarization beam splitter with silicon subwavelength-grating waveguides. OPTICS LETTERS 2020; 45:2259-2262. [PMID: 32287208 DOI: 10.1364/ol.389207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/10/2020] [Indexed: 06/11/2023]
Abstract
An ultra-broadband polarization beam splitter (PBS) with low excess loss (EL) and a high extinction ratio (ER) is proposed and demonstrated for the case with 340 nm thick silicon-on-insulator waveguides. Here the PBS is realized by using cascaded adiabatic dual-core tapers, which consist of a strip core and a subwavelength-grating core. For the designed PBS, which has a 33.6 µm long mode-evolution region, the ELs are ${ \lt }{0.3}\;{\rm dB}$<0.3dB, and the ERs are ${ \gt }{20}\;{\rm dB}$>20dB for both TE and TM polarizations in an ultra-broad bandwidth of ${ \gt }{270}\;{\rm nm}$>270nm (1400-1670 nm) in theory. For the fabricated PBS, the measured bandwidths for achieving ERs of ${\sim}{20}$∼20 and ${\sim}{25}\;{\rm dB}$∼25dB are 240 and 220 nm, while the 1 dB bandwidth is as large as 230 nm, which are the largest bandwidths reported to date, to the best of our knowledge.
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Stanton EJ, Chiles J, Nader N, Moody G, Volet N, Chang L, Bowers JE, Woo Nam S, Mirin RP. Efficient second harmonic generation in nanophotonic GaAs-on-insulator waveguides. OPTICS EXPRESS 2020; 28:9521-9532. [PMID: 32225558 DOI: 10.1364/oe.389423] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/05/2020] [Indexed: 06/10/2023]
Abstract
Nonlinear frequency conversion plays a crucial role in advancing the functionality of next-generation optical systems. Portable metrology references and quantum networks will demand highly efficient second-order nonlinear devices, and the intense nonlinear interactions of nanophotonic waveguides can be leveraged to meet these requirements. Here we demonstrate second harmonic generation (SHG) in GaAs-on-insulator waveguides with unprecedented efficiency of 40 W-1 for a single-pass device. This result is achieved by minimizing the propagation loss and optimizing phase-matching. We investigate surface-state absorption and design the waveguide geometry for modal phase-matching with tolerance to fabrication variation. A 2.0 µm pump is converted to a 1.0 µm signal in a length of 2.9 mm with a wide signal bandwidth of 148 GHz. Tunable and efficient operation is demonstrated over a temperature range of 45 °C with a slope of 0.24 nm/°C. Wafer-bonding between GaAs and SiO2 is optimized to minimize waveguide loss, and the devices are fabricated on 76 mm wafers with high uniformity. We expect this device to enable fully integrated self-referenced frequency combs and high-rate entangled photon pair generation.
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Wan Y, Shang C, Huang J, Xie Z, Jain A, Norman J, Chen B, Gossard AC, Bowers JE. Low Dark Current 1.55 Micrometer InAs Quantum Dash Waveguide Photodiodes. ACS NANO 2020; 14:3519-3527. [PMID: 32083840 DOI: 10.1021/acsnano.9b09715] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photodiodes and integrated optical receivers operating at 1.55 micrometer (μm) wavelength are crucial for long-haul communication and data transfer systems. In this paper, we report C-band InAs quantum dash (Qdash) waveguide photodiodes (PDs) with a record-low dark current of 5 pA, a responsivity of 0.26 A/W at 1.55 μm, and open eye diagrams up to 10 Gb/s. These Qdash-based PDs leverage the same epitaxial layers and processing steps as Qdash lasers and can thus be integrated with laser sources for power monitors or amplifiers for preamplified receivers, manifesting themselves as a promising alternative to their InGaAs and Ge counterparts in low-power optical communication links.
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Chang L, Xie W, Shu H, Yang QF, Shen B, Boes A, Peters JD, Jin W, Xiang C, Liu S, Moille G, Yu SP, Wang X, Srinivasan K, Papp SB, Vahala K, Bowers JE. Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators. Nat Commun 2020; 11:1331. [PMID: 32165610 PMCID: PMC7067760 DOI: 10.1038/s41467-020-15005-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 02/10/2020] [Indexed: 12/04/2022] Open
Abstract
Recent advances in nonlinear optics have revolutionized integrated photonics, providing on-chip solutions to a wide range of new applications. Currently, state of the art integrated nonlinear photonic devices are mainly based on dielectric material platforms, such as Si3N4 and SiO2. While semiconductor materials feature much higher nonlinear coefficients and convenience in active integration, they have suffered from high waveguide losses that prevent the realization of efficient nonlinear processes on-chip. Here, we challenge this status quo and demonstrate a low loss AlGaAs-on-insulator platform with anomalous dispersion and quality (Q) factors beyond 1.5 × 106. Such a high quality factor, combined with high nonlinear coefficient and small mode volume, enabled us to demonstrate a Kerr frequency comb threshold of only ∼36 µW in a resonator with a 1 THz free spectral range, ∼100 times lower compared to that in previous semiconductor platforms. Moreover, combs with broad spans (>250 nm) have been generated with a pump power of ∼300 µW, which is lower than the threshold power of state-of the-art dielectric micro combs. A soliton-step transition has also been observed for the first time in an AlGaAs resonator.
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Chow WW, Liu S, Zhang Z, Bowers JE, Sargent M. Multimode description of self-mode locking in a single-section quantum-dot laser. OPTICS EXPRESS 2020; 28:5317-5330. [PMID: 32121755 DOI: 10.1364/oe.382821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/19/2020] [Indexed: 06/10/2023]
Abstract
This paper describes a theory for mode locking and frequency comb generation by four-wave mixing in a semiconductor quantum-dot active medium. The derivation uses a multimode semiclassical laser theory that accounts for fast carrier collisions within an inhomogeneous distribution of quantum dots. Numerical simulations are presented to illustrate the role of active medium nonlinearities in mode competition, gain saturation, carrier-induced refractive index and creation of combination tones that lead to locking of beat frequencies among lasing modes in the presence of cavity material dispersion.
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Boes A, Chang L, Knoerzer M, Nguyen TG, Peters JD, Bowers JE, Mitchell A. Improved second harmonic performance in periodically poled LNOI waveguides through engineering of lateral leakage. OPTICS EXPRESS 2019; 27:23919-23928. [PMID: 31510289 DOI: 10.1364/oe.27.023919] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
In this contribution, we investigate the impact of lateral leakage for linear and nonlinear optical waveguides in lithium niobate on an insulator (LNOI). Silicon nitride (SiN) loaded and direct patterned lithium niobate cross-sections are investigated. We show that lateral leakage can take place for the TE mode in LNOI ridge waveguides (X-cut lithium niobate), due to the birefringence of the material. This work gives guidelines for designing waveguides in LNOI that do not suffer from the lateral leakage effect. By applying these design considerations, we avoided the lateral leakage effect at the second harmonic wavelength of a nonlinear optical waveguide in LNOI and demonstrate a peak second harmonic generation conversion efficiency of ~1160% W-1cm-2.
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Chang L, Boes A, Pintus P, Xie W, Peters JD, Kennedy MJ, Jin W, Guo XW, Yu SP, Papp SB, Bowers JE. Low loss (Al)GaAs on an insulator waveguide platform. OPTICS LETTERS 2019; 44:4075-4078. [PMID: 31415550 DOI: 10.1364/ol.44.004075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/14/2019] [Indexed: 06/10/2023]
Abstract
In this Letter, we demonstrate a low loss gallium arsenide and aluminum gallium arsenide on an insulator platform by heterogenous integration. The resonators on this platform exhibit record high quality factors up to 1.5×106, corresponding to a propagation loss ∼0.4 dB/cm. For the first time, to the best of our knowledge, the loss of integrated III-V semiconductor on insulator waveguides becomes comparable with that of the silicon-on-insulator waveguides. This Letter should have a significant impact on photonic integrated circuits (PICs) and become an essential building block for the evolving nonlinear PICs and integrated quantum photonic systems in the future.
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