Photoacoustic (PA) remote sensing (PARS) microscopy represents a significant advancement by eliminating the need for traditional acoustic coupling media in PA microscopy (PAM), thereby broadening its potential applications. However, current PARS microscopy setups predominantly rely on free-space optical components, which can be cumbersome to implement and limit the scope of imaging applications. In this study, we develop an all-fiber miniature non-contact PA probe based on PARS microscopy, utilizing a 532-nm excitation wavelength, and showcase its effectiveness in in vivo vascular imaging. Our approach integrates various fiber-optic components, including a wavelength division multiplexer, a mode field adaptor, a fiber lens, and an optical circulator, to streamline the implementation of the PARS microscopy system. Additionally, we have successfully developed a miniature PA probe with a diameter of 4 mm. The efficacy of our imaging setup is demonstrated through in vivo imaging of mouse brain vessels. By introducing this all-fiber miniature PA probe, our work may open up new opportunities for non-contact PAM applications.
光声(PA)遥感(PARS)显微镜无需使用传统的 PA 显微镜(PAM)中的声耦合介质,从而拓宽了其潜在应用领域,是一项重大进步。然而,目前的 PARS 显微镜装置主要依赖于自由空间光学元件,实施起来非常麻烦,而且限制了成像应用的范围。在本研究中,我们利用 532-nm 的激发波长,开发了一种基于 PARS 显微镜的全光纤微型非接触式 PA 探头,并展示了其在体内血管成像中的有效性。我们的方法集成了各种光纤组件,包括波分复用器、模式场适配器、光纤透镜和光循环器,以简化 PARS 显微系统的实施。此外,我们还成功开发了直径为 4 毫米的微型 PA 探头。通过对小鼠脑血管的活体成像,证明了我们成像装置的功效。通过引入这种全纤维微型 PA 探头,我们的工作可能会为非接触式 PAM 应用带来新的机遇。
{"title":"All-fiber miniature non-contact photoacoustic probe based on photoacoustic remote sensing microscopy for vascular imaging in vivo.","authors":"Xingye Tang, Jiasheng Zhou, Siqi Liang, Jitong Zhang, Junjie Xiong, Lin Ma, Sung-Liang Chen","doi":"10.1364/OL.539208","DOIUrl":"https://doi.org/10.1364/OL.539208","url":null,"abstract":"<p><p>Photoacoustic (PA) remote sensing (PARS) microscopy represents a significant advancement by eliminating the need for traditional acoustic coupling media in PA microscopy (PAM), thereby broadening its potential applications. However, current PARS microscopy setups predominantly rely on free-space optical components, which can be cumbersome to implement and limit the scope of imaging applications. In this study, we develop an all-fiber miniature non-contact PA probe based on PARS microscopy, utilizing a 532-nm excitation wavelength, and showcase its effectiveness in in vivo vascular imaging. Our approach integrates various fiber-optic components, including a wavelength division multiplexer, a mode field adaptor, a fiber lens, and an optical circulator, to streamline the implementation of the PARS microscopy system. Additionally, we have successfully developed a miniature PA probe with a diameter of 4 mm. The efficacy of our imaging setup is demonstrated through in vivo imaging of mouse brain vessels. By introducing this all-fiber miniature PA probe, our work may open up new opportunities for non-contact PAM applications.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fields with frequencies below megahertz are challenging for Rydberg-atom-based measurements, due to the low-frequency electric field screening effect caused by the alkali-metal atoms adsorbed on the inner surface of the container. In this paper, we investigate electric field measurements in the ultralow frequency (ULF), very low frequency (VLF), and low frequency (LF) bands in a Cs vapor cell with built-in parallel electrodes. With optimization of the applied DC field, we achieve high-sensitive detection of the electric field at frequencies of 1 kHz, 10 kHz, and 100 kHz based on the Rydberg-atom sensor, with the minimum electric field strength down to 18.0 μV/cm, 6.9 μV/cm, and 3.0 μV/cm, respectively. The corresponding sensitivity is 5.7 μV/cm/Hz1/2, 2.2 μV/cm/Hz1/2, and 0.95 μV/cm/Hz1/2 for the ULF, VLF, and LF fields, which is better than a 1-cm dipole antenna. Besides, the linear dynamic range of the Rydberg-atom sensor is over 50 dB. This work presents the potential to enable more applications that utilize atomic sensing technology in the ULF, VLF, and LF fields.
{"title":"High sensitivity measurement of ULF, VLF, and LF fields with a Rydberg-atom sensor.","authors":"Mingwei Lei, Meng Shi","doi":"10.1364/OL.539090","DOIUrl":"https://doi.org/10.1364/OL.539090","url":null,"abstract":"<p><p>Fields with frequencies below megahertz are challenging for Rydberg-atom-based measurements, due to the low-frequency electric field screening effect caused by the alkali-metal atoms adsorbed on the inner surface of the container. In this paper, we investigate electric field measurements in the ultralow frequency (ULF), very low frequency (VLF), and low frequency (LF) bands in a Cs vapor cell with built-in parallel electrodes. With optimization of the applied DC field, we achieve high-sensitive detection of the electric field at frequencies of 1 kHz, 10 kHz, and 100 kHz based on the Rydberg-atom sensor, with the minimum electric field strength down to 18.0 μV/cm, 6.9 μV/cm, and 3.0 μV/cm, respectively. The corresponding sensitivity is 5.7 μV/cm/Hz<sup>1/2</sup>, 2.2 μV/cm/Hz<sup>1/2</sup>, and 0.95 μV/cm/Hz<sup>1/2</sup> for the ULF, VLF, and LF fields, which is better than a 1-cm dipole antenna. Besides, the linear dynamic range of the Rydberg-atom sensor is over 50 dB. This work presents the potential to enable more applications that utilize atomic sensing technology in the ULF, VLF, and LF fields.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chen Cheng, Mingming Zhang, Junda Chen, Zhijin Zhao, Weihao Li, Can Zhao, Ming Tang
Multipath interference (MPI) noise induces drastic fluctuations in high-speed 4-level pulse amplitude modulation (PAM4) intensity modulation direct detection (IMDD) systems, severely degrading the transmission performance. Here, we propose a bias-aided decision-directed least mean square (DD-LMS) equalizer to eliminate the MPI noise. In the simulation, the proposed bias-aided DD-LMS equalizer could adeptly track and compensate the MPI-impaired PAM4 signal, markedly improving the bit error rate (BER) performance under different MPI levels and laser linewidths. Within a 112 Gbps PAM4 transmission system, the proposed equalizer achieves a MPI tolerance over 4 dB at the KP4-forward error correction (FEC) threshold (2.4 × 10-4), outperforming existing MPI suppression techniques.
{"title":"Bias-aided DD-LMS equalizer for optical multipath-interference-impaired high-speed PAM4 transmission systems.","authors":"Chen Cheng, Mingming Zhang, Junda Chen, Zhijin Zhao, Weihao Li, Can Zhao, Ming Tang","doi":"10.1364/OL.533587","DOIUrl":"https://doi.org/10.1364/OL.533587","url":null,"abstract":"<p><p>Multipath interference (MPI) noise induces drastic fluctuations in high-speed 4-level pulse amplitude modulation (PAM4) intensity modulation direct detection (IMDD) systems, severely degrading the transmission performance. Here, we propose a bias-aided decision-directed least mean square (DD-LMS) equalizer to eliminate the MPI noise. In the simulation, the proposed bias-aided DD-LMS equalizer could adeptly track and compensate the MPI-impaired PAM4 signal, markedly improving the bit error rate (BER) performance under different MPI levels and laser linewidths. Within a 112 Gbps PAM4 transmission system, the proposed equalizer achieves a MPI tolerance over 4 dB at the KP4-forward error correction (FEC) threshold (2.4 × 10<sup>-4</sup>), outperforming existing MPI suppression techniques.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142365998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuxin Lu, Wenjing Zhao, Aiping Zhai, Nuo Liu, Dong Wang
Single-pixel phase imaging (SPPI) utilizes a single-pixel detector combined with interferometry to capture phase information of an unknown field. However, to reconstruct an M × N image, normally M × N modulations and detections are required, leading to a long imaging time for SPPI. Here, a complex-valued Zernike basis SPPI (Zernike-SPPI) is proposed to achieve phase reconstruction at as high quality as possible with a very low sampling ratio. Simulations and experiments demonstrate that Zernike-SPPI achieves better imaging quality at a sampling ratio of less than 10% compared to the state-of-the-art SPPI techniques based on Hadamard basis. This means Zernike-SPPI can obtain a high-quality phase image with less imaging time. This work offers a solution to achieve fast SPPI while guaranteeing quality phase reconstruction as high as possible.
单像素相位成像(SPPI)利用单像素探测器结合干涉测量法来捕捉未知场的相位信息。然而,要重建 M × N 幅图像,通常需要 M × N 次调制和检测,导致 SPPI 的成像时间较长。这里提出了一种复值 Zernike 基 SPPI(Zernike-SPPI),以尽可能低的采样比实现高质量的相位重建。模拟和实验证明,与基于 Hadamard 基的最先进 SPPI 技术相比,Zernike-SPPI 在采样率低于 10% 的情况下能获得更好的成像质量。这意味着 Zernike-SPPI 能以更短的成像时间获得高质量的相位图像。这项工作提供了一种既能实现快速 SPPI,又能保证尽可能高的相位重建质量的解决方案。
{"title":"Single-pixel phase imaging via a complex-valued Zernike basis.","authors":"Yuxin Lu, Wenjing Zhao, Aiping Zhai, Nuo Liu, Dong Wang","doi":"10.1364/OL.538196","DOIUrl":"https://doi.org/10.1364/OL.538196","url":null,"abstract":"<p><p>Single-pixel phase imaging (SPPI) utilizes a single-pixel detector combined with interferometry to capture phase information of an unknown field. However, to reconstruct an M × N image, normally M × N modulations and detections are required, leading to a long imaging time for SPPI. Here, a complex-valued Zernike basis SPPI (Zernike-SPPI) is proposed to achieve phase reconstruction at as high quality as possible with a very low sampling ratio. Simulations and experiments demonstrate that Zernike-SPPI achieves better imaging quality at a sampling ratio of less than 10% compared to the state-of-the-art SPPI techniques based on Hadamard basis. This means Zernike-SPPI can obtain a high-quality phase image with less imaging time. This work offers a solution to achieve fast SPPI while guaranteeing quality phase reconstruction as high as possible.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As multimedia service demands rise, radio-over-fiber (RoF) systems necessitate a flexible wireless resource allocation in multi-user scenarios. Optical wavelength division multiplexing (WDM) can meet multi-user application scenarios but has the problems of high hardware cost and complexity. In this Letter, we propose a photonic-aided reconfigurable multichannel vector millimeter-wave (mm-wave) transmission scheme in the RoF system enabled by the digital subcarrier multiplexing (DSCM) technique. The scheme can flexibly adjust the number and frequency spacing of subcarriers as well as the bandwidth and modulation format allocated to each subcarrier, and it can be applied to multi-user scenarios without increasing the cost and complexity of hardware implementation. The off-line experiments verify the system transmission performance with different numbers, bandwidth, and frequency spacing of subcarriers, fully verifying the feasibility of the scheme. Furthermore, the Letter delves into the effects of the subcarrier number, bandwidth, and frequency spacing on overall system performance, highlighting the potential of this scheme for flexible and cost-effective wireless resource allocation in RoF systems.
{"title":"W-band photonic-aided reconfigurable multichannel vector mm-wave transmission enabled by the digital subcarrier multiplexing technique.","authors":"Liye Fang, Tangyao Xie, Xinying Li, Xiaolong Pan, Jiahao Bi, Hengxin Yan, Jiawei Wang, Gang Li, Xiangjun Xin","doi":"10.1364/OL.534460","DOIUrl":"https://doi.org/10.1364/OL.534460","url":null,"abstract":"<p><p>As multimedia service demands rise, radio-over-fiber (RoF) systems necessitate a flexible wireless resource allocation in multi-user scenarios. Optical wavelength division multiplexing (WDM) can meet multi-user application scenarios but has the problems of high hardware cost and complexity. In this Letter, we propose a photonic-aided reconfigurable multichannel vector millimeter-wave (mm-wave) transmission scheme in the RoF system enabled by the digital subcarrier multiplexing (DSCM) technique. The scheme can flexibly adjust the number and frequency spacing of subcarriers as well as the bandwidth and modulation format allocated to each subcarrier, and it can be applied to multi-user scenarios without increasing the cost and complexity of hardware implementation. The off-line experiments verify the system transmission performance with different numbers, bandwidth, and frequency spacing of subcarriers, fully verifying the feasibility of the scheme. Furthermore, the Letter delves into the effects of the subcarrier number, bandwidth, and frequency spacing on overall system performance, highlighting the potential of this scheme for flexible and cost-effective wireless resource allocation in RoF systems.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Letter delves into an approach to holographic image denoising, drawing inspiration from the generative paradigm. It introduces a conditional diffusion model framework that effectively suppresses twin-image noises and speckle noises in dense particle fields with a large depth of field (DOF). Specific training and inference configurations are meticulously outlined. For evaluation, the method is tested using calibration dot board data and droplet field data, encompassing gel atomization captured via inline holography and aviation kerosene swirl spray through off-axis holography. The performance is assessed using three distinct metrics. The metric outcomes, along with representative examples, robustly demonstrate its superior noise reduction, detail preservation, and generalization capabilities when compared to two other methods. The proposed method not only pioneers the field of generative holographic image denoising but also highlights its potential for industrial applications, given its reduced dependency on high-quality training labels.
{"title":"Holographic image denoising for dense droplet field using conditional diffusion model.","authors":"Hang Zhang, Yu Wang, Yingchun Wu, Letian Zhang, Boyi Wang, Yue Zhao, Xuecheng Wu","doi":"10.1364/OL.538939","DOIUrl":"https://doi.org/10.1364/OL.538939","url":null,"abstract":"<p><p>The Letter delves into an approach to holographic image denoising, drawing inspiration from the generative paradigm. It introduces a conditional diffusion model framework that effectively suppresses twin-image noises and speckle noises in dense particle fields with a large depth of field (DOF). Specific training and inference configurations are meticulously outlined. For evaluation, the method is tested using calibration dot board data and droplet field data, encompassing gel atomization captured via inline holography and aviation kerosene swirl spray through off-axis holography. The performance is assessed using three distinct metrics. The metric outcomes, along with representative examples, robustly demonstrate its superior noise reduction, detail preservation, and generalization capabilities when compared to two other methods. The proposed method not only pioneers the field of generative holographic image denoising but also highlights its potential for industrial applications, given its reduced dependency on high-quality training labels.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jian Su, Ruihuan Wu, Bo Li, Weiyi Hong, Shengde Liu, Hongzhan Liu
A novel approach, to the best of our knowledge, for generating short microwave pulse trains based on a hybrid mode-locked optoelectronic oscillator (HML-OEO) is proposed and demonstrated. In the proposed scheme, a saturable absorber (SA) device is inserted into the active mode-locked OEO (AML-OEO) to compress the pulse width of the microwave pulse trains. Numerical simulations and experimental results show that the HML-OEO generates a short microwave pulse train with a repetition rate of 98.994 kHz through fundamental frequency mode locking, and its pulse width is compressed by about 50% compared to the AML-OEO. Additionally, in the experiment, microwave pulse trains with different repetition rates are generated by second-, third-, fourth-, and fifth-order harmonic mode locking, respectively. Compared to the AML-OEO, the HML-OEO achieves pulse compression effects of 49.3%, 49.8%, 49.4%, and 49.9%, respectively. Notably, compared to the AML-OEO, the proposed scheme also exhibits outstanding performance in frequency stability.
{"title":"Generation of short microwave pulse trains based on a hybrid mode-locked optoelectronic oscillator.","authors":"Jian Su, Ruihuan Wu, Bo Li, Weiyi Hong, Shengde Liu, Hongzhan Liu","doi":"10.1364/OL.540176","DOIUrl":"https://doi.org/10.1364/OL.540176","url":null,"abstract":"<p><p>A novel approach, to the best of our knowledge, for generating short microwave pulse trains based on a hybrid mode-locked optoelectronic oscillator (HML-OEO) is proposed and demonstrated. In the proposed scheme, a saturable absorber (SA) device is inserted into the active mode-locked OEO (AML-OEO) to compress the pulse width of the microwave pulse trains. Numerical simulations and experimental results show that the HML-OEO generates a short microwave pulse train with a repetition rate of 98.994 kHz through fundamental frequency mode locking, and its pulse width is compressed by about 50<i>%</i> compared to the AML-OEO. Additionally, in the experiment, microwave pulse trains with different repetition rates are generated by second-, third-, fourth-, and fifth-order harmonic mode locking, respectively. Compared to the AML-OEO, the HML-OEO achieves pulse compression effects of 49.3<i>%</i>, 49.8<i>%</i>, 49.4<i>%</i>, and 49.9<i>%</i>, respectively. Notably, compared to the AML-OEO, the proposed scheme also exhibits outstanding performance in frequency stability.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The diffraction efficiencies of a complex binary diffraction grating with a rectangular profile are controlled through the steps' phases, amplitudes, and duty cycle, based on analytical expressions. It is demonstrated that the zeroth-diffraction order can be canceled for any arbitrary value of the duty cycle, provided that a π-phase difference is imposed, along with a specific ratio of the steps' amplitudes. This feature is not feasible for separated amplitude-only and phase-only rectangular binary gratings in the context of one-dimensional gratings. In this framework, a key analytic relationship between the duty cycle and the steps' amplitude ratio is derived, allowing the design of such gratings with this desired feature across a wide range of conditions, not limited to a duty cycle of 0.5. Concerning the higher diffraction orders, it is proved that their intensities cancel or maximize for fixed duty cycle no matter the amplitude and phase values of the steps. The intensity of the m-th diffraction order possesses m maxima and m - 1 zeros on the full range of the duty cycle. All these features were corroborated experimentally. The broad insight of such a grating allows the design of gratings with diffraction efficiencies tailored for specific applications.
根据分析表达式,通过阶跃相位、振幅和占空比来控制矩形轮廓复杂二元衍射光栅的衍射效率。结果表明,只要施加 π 相位差和特定的阶跃振幅比,在占空比为任意值的情况下,都能消除第零衍射阶。在一维光栅的背景下,这一特性对于只分离振幅和只分离相位的矩形二元光栅来说是不可行的。在这一框架中,得出了占空比和阶跃振幅比之间的关键分析关系,从而可以在多种条件下设计出具有这一理想特性的光栅,而不仅限于占空比为0.5的条件。关于更高的衍射阶数,研究证明,无论阶数的振幅和相位值如何,在固定占空比的情况下,它们的强度都会抵消或最大化。第 m 个衍射阶的强度在整个占空比范围内有 m 个最大值和 m - 1 个零值。所有这些特征都在实验中得到了证实。这种光栅具有广阔的洞察力,可根据特定应用设计具有衍射效率的光栅。
{"title":"Diffraction efficiency management by complex binary gratings.","authors":"Dafne Amaya, Edgar Rueda, Pablo Vaveliuk","doi":"10.1364/OL.531872","DOIUrl":"https://doi.org/10.1364/OL.531872","url":null,"abstract":"<p><p>The diffraction efficiencies of a complex binary diffraction grating with a rectangular profile are controlled through the steps' phases, amplitudes, and duty cycle, based on analytical expressions. It is demonstrated that the zeroth-diffraction order can be canceled for any arbitrary value of the duty cycle, provided that a π-phase difference is imposed, along with a specific ratio of the steps' amplitudes. This feature is not feasible for separated amplitude-only and phase-only rectangular binary gratings in the context of one-dimensional gratings. In this framework, a key analytic relationship between the duty cycle and the steps' amplitude ratio is derived, allowing the design of such gratings with this desired feature across a wide range of conditions, not limited to a duty cycle of 0.5. Concerning the higher diffraction orders, it is proved that their intensities cancel or maximize for fixed duty cycle no matter the amplitude and phase values of the steps. The intensity of the m-th diffraction order possesses m maxima and m - 1 zeros on the full range of the duty cycle. All these features were corroborated experimentally. The broad insight of such a grating allows the design of gratings with diffraction efficiencies tailored for specific applications.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Extending lasing wavelengths to the mid-infrared (MIR) spectrum is vital for both civilian and military applications; however, it remains challenging when employing oxide nonlinear optical crystals. In this study, we report the generation of MIR nanosecond pulses via difference frequency generation (DFG) with a near-IR pump using a newly designed langasite (LGS) crystal, La3(Nb0.6Ta0.4)0.5Ga5.5O14 (LGNT0.4), which incorporates birefringence dispersion management techniques with La3Ga5.5Nb0.5O14 (LGN) as a template. Due to the improved effective nonlinear coefficients and the maintained IR cutoff relative to LGN, the tunable DFG laser in LGNT0.4 extended from 4.24 to 6.84 μm, delivering a maximum pulse energy of 16.3 μJ at 5.02 μm. To the best of our knowledge, this is the first known oxide material capable of generating tunable nanosecond pulsed lasers beyond 6 μm at μJ-level energies, demonstrating promising potential for high-intensity MIR laser systems owing to its high laser damage threshold.
{"title":"Extending mid-infrared wavelength to 6.84 μm in oxide nonlinear optical crystal via birefringence dispersion management.","authors":"Hongxu Gu, Dazhi Lu, Chen Cui, Fei Liang, Kui Wu, Haohai Yu, Huaijin Zhang","doi":"10.1364/OL.535134","DOIUrl":"https://doi.org/10.1364/OL.535134","url":null,"abstract":"<p><p>Extending lasing wavelengths to the mid-infrared (MIR) spectrum is vital for both civilian and military applications; however, it remains challenging when employing oxide nonlinear optical crystals. In this study, we report the generation of MIR nanosecond pulses via difference frequency generation (DFG) with a near-IR pump using a newly designed langasite (LGS) crystal, La<sub>3</sub>(Nb<sub>0.6</sub>Ta<sub>0.4</sub>)<sub>0.5</sub>Ga<sub>5.5</sub>O<sub>14</sub> (LGNT<sub>0.4</sub>), which incorporates birefringence dispersion management techniques with La<sub>3</sub>Ga<sub>5.5</sub>Nb<sub>0.5</sub>O<sub>14</sub> (LGN) as a template. Due to the improved effective nonlinear coefficients and the maintained IR cutoff relative to LGN, the tunable DFG laser in LGNT<sub>0.4</sub> extended from 4.24 to 6.84 μm, delivering a maximum pulse energy of 16.3 μJ at 5.02 μm. To the best of our knowledge, this is the first known oxide material capable of generating tunable nanosecond pulsed lasers beyond 6 μm at μJ-level energies, demonstrating promising potential for high-intensity MIR laser systems owing to its high laser damage threshold.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose an integrated resonant structure to enhance squeezing by dual-pump spontaneous four-wave mixing (SFWM) while simultaneously suppressing parametric noise due to parasitic processes. The structure relies on a resonant interferometric coupler that allows one to engineer the field enhancement on-demand in the spectral region of interest. We analyze the different configurations in which the structure can operate, and we calculate the generated squeezing. We show that our device can overcome the intrinsic squeezing limit of a single-ring resonator.
{"title":"Squeezing enhancement by suppression of noise through a resonant interferometric coupler.","authors":"Alice Viola, Francesco Malaspina, Marco Liscidini","doi":"10.1364/OL.532868","DOIUrl":"https://doi.org/10.1364/OL.532868","url":null,"abstract":"<p><p>We propose an integrated resonant structure to enhance squeezing by dual-pump spontaneous four-wave mixing (SFWM) while simultaneously suppressing parametric noise due to parasitic processes. The structure relies on a resonant interferometric coupler that allows one to engineer the field enhancement on-demand in the spectral region of interest. We analyze the different configurations in which the structure can operate, and we calculate the generated squeezing. We show that our device can overcome the intrinsic squeezing limit of a single-ring resonator.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":null,"pages":null},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142366054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}