Journal Club 2023 | Tanabe Photonic Structure Group

Journal Club

By fiscal year (April-December)

Fiscal Year 2023

Presentation Details:

Over the past decade, passive, nonlinear optical resonators have emerged as a new method for generating ultrashort optical pulses and the corresponding broadband frequency comb. This study explores a new method for generating ultrashort pulses using passive resonators. By taking advantage of silica's inherent nonlinear Raman amplification, low-noise dissipative solitons with durations well below 100 fs have been successfully and decisively generated via resonator phase-locked pulses generated by standard commercial optical fibers. The physics of the new dissipative Raman soliton state is explored to identify the scaling laws governing the pulse characteristics, allowing the output repetition rate to be freely scaled without affecting the soliton duration. The technique achieves the shortest pulses ever generated in commercially available optical fiber (active or passive) and has the potential to be transferred to chip-scale formats using existing dispersion-engineered silica microcavities.

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Optical chaos is vital for various applications such as private communication, encryption, anti-interference sensing, and reinforcement learning. Chaotic microcombs have emerged as promising sources for generating massive optical chaos. In this study, we present massively parallel In this study, we present massively parallel chaos based on chaotic microcombs and high-nonlinearity AlGaAsOI platforms. We further show the application of our approach by demonstrating a 15-channel integrated random bit We further show the application of our approach by demonstrating a 15-channel integrated random bit generator with a 20 Gbps channel rate using silicon photonic chips. Our work opens new possibilities for chaos-based information processing Our work opens new possibilities for chaos-based information processing using integrated photonics, and potentially can revolutionize the current architecture of communication, sensing and computations.

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This work proposes a novel dual-mode photonic-crystal waveguide that realizes direct in-plane resonant excitation of the embedded QDs. The device relies on a two-mode waveguide design, which allows exploiting one mode for excitation of the QD and the other mode for collecting the emitted single By proper engineering of the photonic band-structure, single-photon collection efficiency of β > 0.95 together with a The device has a compact footprint of ∼50 μm2 and would The device has a compact footprint of ∼50 μm2 and would enable stable and scalable excitation of multiple emitters for multi-photon quantum applications.

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Soliton microcombs have shown great promise as a photonics-derived low-noise microwave generation technology. However, the repetition rate of a microcomb is basically determined by the size of the resonator, limiting the ability to tune the broadband and fast frequency by tuning the heat and pump frequency. In this study, we demonstrate a microwave soliton microcomb that can be tuned at high repetition rates by using a new device configuration. By incorporating electro-optic modulators along the ring waveguide, we succeeded in modulating a 75 MHz bandwidth at 5.0x10^14 Hz/s, which is several orders of magnitude faster than the modulation speed of conventional techniques. The device is expected to be applied to many applications including frequency measurement, frequency synthesizer, LiDAR, sensing, and communications.

Presentation Details:

Micro-optical resonators are promising platforms for highly efficient light-matter interactions. In recent years, the combination of nanoscale micro-optical resonators and 2D materials has further enriched optoelectronics in micro-optical resonator geometries, spurring a wide range of advances in lasers, nonlinear converters, modulators, and sensors. Here we report a compact dual laser resonance concept in graphene-microoptical resonator fibers. Driven by a single 980-nm pump, orthogonally polarized laser lines are generated with a pair of mode-breaking degeneracies; the two laser lines produce a heterodyne beat note at 118.96 MHz, with frequency noise down to 200 Hz^2/Hz at a 1-MHz offset, and in vacuum The line width was 930 Hz. This compact instrument allows on-line and label-free detection of ammonia gas with high resolution and a detection limit at the single pmol/L level.

Presentation Details:

In this paper we propose and numerically demonstrate a broadband, wavelength tunable Raman soliton source based on an As2Se3 waveguide. The input waveguide exhibits an anomalous dispersion in the near-infrared band, thereby enabling a 1.96 μm light source for Raman soliton self-frequency shift (SSFS) excitation. The output waveguide exhibits large anomalous dispersion and good mode confinement in the mid-IR band, thus supporting further SSFS processes. 2.29-4.57 μm wavelength tunable Raman light sources are theoretically realized on this on-chip platform. This study presents a simple and easy-to-implement strategy for extending the tuning range of the light source. The proposed tunable wavelength light source has great potential in integrated spectroscopy, gas detection, and LiDAR applications.

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The high-frequency carrier, terahertz (THz) waves, have an ultra-wide bandwidth and are therefore suitable for high data ray
It is essential to achieve wireless transmission of the To enable multi-level modulation, phase
Stabilization is extremely important, and we have previously developed a phase stabilization technique using Mach-Zehnder interferometry.
generated. However, in this method, when generating phase-modulated THz waves, the phase modulator
had a problem of affecting the phase stabilization system. Therefore, we have developed a THz wave generation shi
A new phase stabilization approach was devised using light waves in the opposite direction of the stem. The result
As a result, error-free transmission was demonstrated at modulation frequencies above 3 Gbit/s.

Presentation Details:

An efficient 1.7-μm Tm-doped fiber laser with a resonator incorporated into a 1560-nm erbium/ytterbium resonant fiber laser cavity was demonstrated, and a rate equation model was developed to optimize fiber length and output coupling to achieve the desired output power. Experiments showed a maximum output power of 1.13 W at 1720 nm under a diode pump power of 10 W at 976 nm, which correlated well with the modeling. The slope efficiency from the multimode 976nm diode pump to 1720nm output was 13.5%, and the slope efficiency at the start-up 1560nm pump power reached 62.5%. A high signal-to-noise ratio of over 65 dB was achieved by using a short Tm-doped fiber to minimize signal reabsorption. Further power scaling prospects based on the developed model were also discussed.

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Flat optics has demonstrated great advances in miniaturizing conventional bulky optical elements due to recent developments in metasurface design. Specific applications of such designs include spatial differentiation and the compression of free-space. In this work, we introduce a polarization-independent In this work, we introduce a polarization-independent metasurface structure by designing guided resonances with degenerate band curvatures in a photonic crystal slab. Our device can perform both free- space compression and spatial differentiation when operated at different frequencies at normal incidence. This work demonstrates the promise of dispersion engineering in metasurface design to create ultrathin devices with polarization-independent functionality.

Presentation Details:

We propose a new method to generate single solitons in SiN resonators. The auxiliary laser method pumps two resonances and compensates thermally with one of them, but this method is inefficient because the two resonances are separated by an FSR, which requires a pump and a separate laser. In the present study, by appropriately designing a two-mode resonator and using two resonances with very close resonance frequencies, a soliton was successfully generated with only one pump laser.

Presentation Details:

Optical chaos communication and key distribution have been extensively demonstrated with high-speed advantage but only within the metropolitan-area network range of which the transmission distance is restricted to around 300 km. For secure-transmission requirement of the backbone fiber link, the critical threshold is to realize long-reach chaos synchronization. Here, we propose and demonstrate a scheme of long-reach chaos synchronization Here, we propose and demonstrate a scheme of long-reach chaos synchronization using fiber relay transmission with hybrid amplification of an erbium-doped fiber amplifier (EDFA) and a distributed fiber Raman amplifier (DFRA). Experiments and simulations show that the hybrid amplification extends the chaos-fidelity transmission distance thanks to that the low-noise DFRA Optimizations of the hybrid-relay conditions are studied, including Optimizations of the hybrid-relay conditions are studied, including launching power, gain ratio of DFRA to EDFA, single-span fiber length, and number of fiber span. coefficient beyond 0.90 is experimentally achieved, which underlies the backbone network-oriented optical chaos communication and key distribution .

Presentation Details:

Integrated microwave photonic filters (IMPFs) have broadband and reIt offers superior performance in terms of configurability. However, conventionalIn order to achieve high reconfigurability in the method, complex system structures andThe modulation method must be adopted, which imposes a heavy burden in terms of power consumption and control.The result of this research is the development of a new photonics system on a silicon photonics platform. In this study, we used a silicon photonics platformWe demonstrate a broadband, highly reconfigurable IMPF with BPF andImplement the switchable functionality of both BSF and a wide frequency range ((up to 30 GHz), high rejection ratio (about 60 dB at BSF), and high spectral resolution (220 MHz). The practicality of the proposed IMPF was also verifiedIn order to do so, fast channel selectivity experiments andStrong interference suppression experiments were performed. High resolution, highIMPF, with its superior performance such as reconfigurability, is the root of 6G communications.The new system eliminates the bottleneck of microwave and millimeter-wave applications, and enables the use of various microwave and millimeter-wave applications.The new system will be important for the realization of the

Presentation Details:

Polarization selective elements can control the polarization of an optical system.The results are shown in Figure 1. We have used silica microspheres and monolayerCompact hybrid structures based on graphene have been developed... The principle of this operation is the Whispering Gallery (WG) TE moof graphene combined with silica microspheres via TM mode andPolarization-dependent absorption. The electric field distribution of the resonance mode of the microsphere and the polarization state are different.Therefore, the gap distance between the microspheres and graphene will affect theThe Q value and resonance wavelength of the TE and TM modes can be changed.The WG mode of the WG can realize different changes for each of them.When the gap distance is reduced from 2.2 µm to 0.3 µm, the resonant polarization mode in the 90° polarization direction and the 0° polarization directionA polarization extinction ratio of 11 dB was achieved between the resonant polarization modes of This result is consistent with the high performance polarization selective elementAn attractive and effective photonic platform to realizeThe following is an example of a product that can be provided.

Presentation Details:

with pseudo-crossing differences, and with certainty.2Observation of soliton formation

Dissipative Kerr solitons in micro resonators (DKS(see Figure 2), theThis decrease is expected to have a variety of applications.DKSAmong the states, thesingleDKSDoubleDKS，Perfect soliton crystals areIt can be simply identified from the optical spectrum. In particular, doubleDKSThe state is the2Due to the nature of the pulse interference, the recently reconstructableradio frequency (RF)phiThe application to a luther has been proposed. However, the conventional doubleDKS"grain in ear" solar term (approx. June 6, when awns begin to grow on grains)In the method of forming the resonator, theDKSThe problem of stochastic changes in the relative angles ofThe paper is based on a study of the effects of the "H" in the "H" in the "H". In this paper, the97 GHz(at sentence-end, falling tone) indicates a confident conclusionsilicon nitride (SiN)In the micro resonator, theDual pumping system allows for a fixed relative angle doubleDKSindicates object of desire, like, hate, etc.We demonstrated a method to reliably generate the soliton. The relative angles of the solitons and theAMan unknowndue toCWThe relationship between the background and theDKSdieProvides new knowledge about namics.

Presentation Details:

Multipoint side pump 2.825µm high density el.The power and thermal characteristics of a bium-doped fluoride fiber laser were investigated by numerical simulation. Numerical simulations were performed on the output power and thermal characteristics of a polishedErbium-doped fluoride fiber-based side pump coupler.The four-point (or six-point) erbium-doped fluoride fiber lasers used are eachThe pump power is 100W (or 75W) at 981nm and 100W (or 75W) at 981nm.Laser output power in excess of 1 W was achieved. On the other hand, the core temperature rise of the gain fiber chip is less than 1 K, which enables stable operation of the highly reflective fiber Bragg grating at high power operation.The company is able to Multipoint side-pumped fiber-based side-poThe process of preparing end caps with couplers and effective coatings has been accomplished.When mature, the proposed multi-point side-pump erbium-added fluoride faIber lasers have some feasibility and, theoretically, effective thermal management.This could pave the way for the development of a 100W mid-infrared fiber laser with

Presentation Details:

To deploy spectrometers on mobile platforms, small spectrometersA new concept for the development of the device is required. Strong wavelength dependenceThe combination of an element with a point spread function that exhibits aThe concept of a "Computational Spectrometer" is a good solution for this new concept. Meta-optimizationThe pixel is designed to manipulate the point spread function and is strongly wavelength dependent.The point spread function is a meta-optic with a double helix. The point spread function draws a double helix with meta-optics.By designing and recording the wavelength dependence of the point spread function, the spectralThe infrared resolution of approximately 3.5 nm was achieved. In the infrared region, a resolution of approximately 3.5 nm was achieved.

Presentation Details:

Advances in integrated photonics have led to the development of highly stable, compact, broadband comb generators for a variety of applications, including communications, distance measurement, spectroscopy, frequency measurement, optical computation, and quantum information. Broadband optical frequency combs are generated in an electro-optic cavity where light passes through a phase modulator multiple times and circulates within an optical cavity. However, current broadband electro-optic frequency combs are limited by their low conversion efficiency. In this study, we demonstrate an integrated electro-optic frequency comb with a conversion efficiency of 301 TP3T and an optical span of 132 nm using a thin-film lithium niobate-based coupling resonator platform. Furthermore, by leveraging the high efficiency, the device can act as an on-chip femtosecond pulse source (pulse width of 336 fs), which is important for applications such as nonlinear optics, sensing, and computation.

Presentation Details:

Expected to be used in automated drivingLight Detection and Ranging (LiDAR)The conventional method forUse a pulsed light sourceTime-of-flight (TOF)systemand chirped light sources.frequency-modulated continuous-wave (FMCW)method and so on. However, theLiDARWith the spread ofThe wavelengths of the two bands are close to each other.LiDARThe loss of accuracy due to mixed signals between the two, andIn addition, there are concerns that accidents may occur as a result. Therefore, we have developedA very chaotic microcomb is used as a light source andCorrelating chaotic time waveforms is practical and resistant to interference.LiDARhas been developed and is introduced here.

Presentation Details:

Compact narrow-linewidth visible lasers are pivotal components for optical sensing, metrology and communications, as well as precision atomic and With an emission bandwidth approaching an octave, titanium-doped sapphire (Ti:Sa) lasers are key tools for producing solid- and near-infrared bands; however, today's commercial Ti:Sa lasers are the key components for optical sensing, metrology and communications, as well as precision atomic and molecular spectroscopy. With an octave approaching an emission bandwidth, titanium-doped sapphire (Ti:Sa) lasers are key tools for producing solid- state lasing across visible and near-infrared bands; however, today's commercial Ti:Sa laser systems require high pump power and rely on In this paper we present a photonic-circuit-integrated Ti:Sa laser that combines the Ti:Sa gain medium In this paper we present a photonic-circuit-integrated Ti:Sa laser that combines the Ti:Sa gain medium with a silicon-nitride-on-sapphire integrated photonics platform, resulting in high portability with minimal power We demonstrate Ti:Sa lasing from 730 nm to 830 nm by tightly confining the pump and lasing modes to a single microring resonator, reducing the Due to the low threshold, turn-key Ti:Sa laser Our prototype photonic-circuit-integrated Ti:Sa laser opens a reliable pathway for broadband tunable lasers in the next generation of active-passive-integrated visible photonics.

Presentation Details:

Abstract: For the first time, to the best of our knowledge, we experimentally demonstrate a high-speed free-space secure optical communication system The effect of atmospheric turbulence on optical chaos synchronization is experimentally investigated via a hot air convection atmospheric turbulence simulator. It is shown that, even under moderately strong turbulent conditions, high-quality chaos Moreover, a secure encryption transmission experiment using a high bias Moreover, a secure encryption transmission experiment using a high bias current induced chaotic carrier for 8-Gbit/s on-off-keying data over a ∼10-m free-space optical link is successfully demonstrated, with a bit-error rate below the FEC threshold of 3 rate below the FEC threshold of 3.8 × 10^-3. This work favorably shows the feasibility of optical chaotic encryption for the free-space optical transmission system.

Presentation Details:

Topological photonic devices with dynamically tunable functions
are highly on demand in practice, but the majority of previously proposed
photonic systems have been limited to fixed performances, once fabricated.
Although several approaches have been proposed for obtaining the tunability
in topological photonic systems, they are limited to first-order topological
states and require rather complicated structures. Herein, second-order
topological properties of rhombic photonic crystals (PCs) are revealed, for
For the first time, enabling to realize tunable photonic devices.
purpose, the conventional square lattice PCs composed of four rigid
Dielectric rods are reshaped to rhomboid ones with preserved inversion
symmetry, which exhibit well-quantized bulk polarizations.
eigenfrequencies of topological edge and corner states depend on the angle
between the neighboring sides of unit cells, the second-order topological
systems exhibit dynamic tunability, being useful for diverse applications
Such as optical switching and flexible beam control.
results for reconfigurable routing limited to special angles, this
lattice-reshaping mechanism has the ability to realize dynamically tunable
routing, extending the realm of applications of topological photonics.
its simplicity and feasibility, this mechanical lattice-reshaping approach
paves the way toward higher-order topological photonic devices with
dynamically controlled functions.

Presentation Details:

Dissipative Kerr solitons (DKS) with high-Q micro optical resonators areAlready in numerous fields due to low noise and wideband parallel comb linesAlthough applied, theThermal twin due to high intra-resonator power and large temperature exchange with the external environmentStability and thermal noise prevent the formation of soliton microcombs, and phase andfrequency noise. In this study, we used theNew method combining high-speed frequency sweep and optical sideband thermal compensationand presented theProvides a simple and reliable way to achieve a single soliton stateThe proposed method is shown in Fig. 1. In addition, by closing the locking loop, the 5.5e-15 (Integration time: 1 sec.)We report the realization of the intra-loop repetition rate instability of

Presentation Details:

Highly sensitive detection of molecules without the use of labels or trapping agentsThe ability to identify is medical diagnosis, threat identification, and environmental monitoring,It is important for basic science. Microtoroidal resonators are,Combined with noise reduction techniques,Label-free single molecule detection has been shown to be possible.However, prior knowledge of the capture agent and target molecule is required.The optical frequency com,High precision of molecules in the evanescent field of a micro optical resonator.Although it may be able to provide spectral information,Biological sensing in air and water has not yet been demonstrated.Coupling and thermal instability, especially in aqueous solutions, and lower Q-values,mode spectral changes, and other obstacles. Here,This is an important issue for single molecule spectroscopy using micro optical resonators,Frequencies at visible to near-infrared wavelengths when immersed in air or in aqueous solutionIt has been realized to generate a few comThe required dispersion is achieved by mode coupling,that this can be achieved by using larger microtoroids.indicated.

Presentation Details:

Soliton microcomputers have been widely studied for their versatilityIt is one of the fields.When used as a precision frequency ruler, the microcomputer has a wide bandwidth positionphase coherence must be exhibited, andThe phase noise of the com line and the corresponding ray width are its parameters.The research is aimed at developing a new method for the production of high performance silicon nitride. This study was conducted to investigate the effect of high silicon nitrideqOscillation using micro resonatorsWe analyzed the optical phase noise dynamics of the soliton microcomb generated by theLine width of some comb lines pon due to Raman self-frequency shift, etc.This is an indication that the line width may be narrower than the line width of the placer...Clarifying the Physical Limits in Phase Coherence of Soliton MicrocombsKani, K.This is a new strategy for generating spectrally coherent light on a chip.The following table shows the results.

Presentation Details:

Er-doped crystals are used in laser diodes (LDs)Excitation with a low-cost
The laser is compact and has a structure near 3 µm.CaF2 and SrF2 crystals have a fluorite structure that allows Er3+ ions to "cluster"and this effect shortens the space between Er3+ ions,Intense interionic energy transfer is brought about within the crystal. Due to the presence of clusters,Not only was the self-terminating process solved, but severe thermal damage during Er3+ 2.8 μm laser generation was also avoided.In this study, we used the temperature gradient method to obtain high-quality 1.7at.%Er:.CaF2 laser crystals were successfully grown, achieving a maximum output power of 2.32 W for the LD-pumped 2756.6 nm laser.This is as laser power generated by LD pumped Er3+ doped fluoride crystals,It is the highest in recent years. In addition, the 1.7at.% Er: by LD excitation at 1532nm.The performance of the CaF2 laser was also demonstrated, proving strong energy transfer within lightly doped Er:CaF2 crystals.These results have been achieved by miniaturization andIt is valuable for the development of mid-infrared lasers aimed at low-costThere are.

Presentation Details:

We propose nanostructures (photonic crystals) whose optical properties change spontaneously only by the application of static voltage to accelerate photonics technology. We have applied the proposed photonic crystals to PCSELs and demonstrated that pulsed oscillation occurs without any external switching operation. This achievement is significant as a new method of PCSEL pulse generation and will lead to a deeper understanding of the phenomena caused by carrier photon dynamics.

Presentation Details:

We have developed a Nd-doped cascade Raman laser for the development of two-photon microscopy for deep biological imaging. In order to suppress the mode competition between 1060nm and 900nm, we developed a mode-locked cascade Raman laser that can be easily fabricated by using bending loss.

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What is Journal Club?
This is an open lecture series held in Tanabe Photonic Structures Laboratory. Students who are graduate students or above will survey papers related to optics and related technologies such as photonics, materials, bioscience, etc., and explain them in an easy-to-understand manner.

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