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Lasers and Laser Optics|220 Article(s)
Ultra-wideband high-speed wavelength-swept DFB laser array and precision measurement system of nonlinear wavelength variations
Yaqiang Fan, Pan Dai, Zhenxing Sun, Yuan Lv, Wei Yuan, Haolin Xia, Jingxuan Zhang, Junwei Dong, Jihong Xu, Jie Zeng, Feng Wang, and Xiangfei Chen
In this study, we developed a robust, ultra-wideband, and high-speed wavelength-swept distributed feedback (DFB) laser array with an 8×3 matrix interleaving structure with no movable or fragile optical components. This wavelength-swept laser (WSL) achieves a continuous (gap-free) wavelength sweeping range of 60 nm and a rapid sweeping speed of 82.7 kHz, marking the widest wavelength sweeping range reported to date for high-speed WSLs based on DFB laser arrays, to our knowledge. To achieve the high-precision mapping from the time domain to the frequency domain, a nonlinear wavelength and frequency variation measurement system based on dual Fabry–Perot (F-P) etalons is designed. The system accurately measures the dynamic relationship of frequency variations over time, enabling precise wavelength interrogation. The proposed WSL was applied to the fiber Bragg grating (FBG) sensor interrogation system. In the high-low temperature and strain experiments, the system performed real-time dynamic interrogation of FBGs for up to 3 h. The experimental results demonstrated good relative accuracy and excellent interrogation performance of the system. In the vibration experiment, the system achieved high-precision interrogation of FBG sensors for high-frequency sinusoidal vibrations up to 8 kHz. Furthermore, the system worked stably under strong vibrations and shocks. Thus, the proposed WSL is applicable to high-speed FBG sensing and optical coherence tomography applications. In this study, we developed a robust, ultra-wideband, and high-speed wavelength-swept distributed feedback (DFB) laser array with an 8×3 matrix interleaving structure with no movable or fragile optical components. This wavelength-swept laser (WSL) achieves a continuous (gap-free) wavelength sweeping range of 60 nm and a rapid sweeping speed of 82.7 kHz, marking the widest wavelength sweeping range reported to date for high-speed WSLs based on DFB laser arrays, to our knowledge. To achieve the high-precision mapping from the time domain to the frequency domain, a nonlinear wavelength and frequency variation measurement system based on dual Fabry–Perot (F-P) etalons is designed. The system accurately measures the dynamic relationship of frequency variations over time, enabling precise wavelength interrogation. The proposed WSL was applied to the fiber Bragg grating (FBG) sensor interrogation system. In the high-low temperature and strain experiments, the system performed real-time dynamic interrogation of FBGs for up to 3 h. The experimental results demonstrated good relative accuracy and excellent interrogation performance of the system. In the vibration experiment, the system achieved high-precision interrogation of FBG sensors for high-frequency sinusoidal vibrations up to 8 kHz. Furthermore, the system worked stably under strong vibrations and shocks. Thus, the proposed WSL is applicable to high-speed FBG sensing and optical coherence tomography applications.
Photonics Research
- Publication Date: Jun. 19, 2025
- Vol. 13, Issue 7, 1855 (2025)
Collisions of heteronuclear dichromatic soliton compounds in a passively mode-locked fiber laser
Yuansheng Ma, Ziyang Zhang, Yu Ning, Jiangyong He, Pan Wang, Yange Liu, Bo Liu, and Zhi Wang
The complexity of multi-dimensional optical wave dynamics arises from the introduction of multiple degrees of freedom and their intricate interactions. In comparison to multimode spatiotemporal mode-locked solitons, expanding the wavelength dimension is also crucial for studying the dynamics of multi-dimensional solitons, with simpler characterization techniques. By inserting a section of zero-dispersion highly nonlinear fiber (HNLF) into a passively mode-locked fiber laser, two heteronuclear dichromatic soliton compounds with different group velocities (GVs) are formed within the resonant cavity of the laser. The cross-phase modulation effect leads to the formation of a robust fast-GV compound (FGC), consisting of a partially coherent dissipative soliton bunch (PCDSB) and dispersion waves (DWs), while a conventional soliton (CS) and a narrow spectral pulse (NSP) form a slow-GV compound (SGC). Multiple SGCs can further interact to form an SGC loosely bound complex. These two types of compounds with different GVs continuously collide and exchange energy through the four-wave mixing (FWM) effect in the HNLF, promoting the annihilation, survival, and regeneration of the SGC complex. This exploration of interactions between asynchronous compounds broadens the study of soliton dynamics in multi-dimensions and offers insights for potential applications in areas such as high-throughput optical communication and optical computing. The complexity of multi-dimensional optical wave dynamics arises from the introduction of multiple degrees of freedom and their intricate interactions. In comparison to multimode spatiotemporal mode-locked solitons, expanding the wavelength dimension is also crucial for studying the dynamics of multi-dimensional solitons, with simpler characterization techniques. By inserting a section of zero-dispersion highly nonlinear fiber (HNLF) into a passively mode-locked fiber laser, two heteronuclear dichromatic soliton compounds with different group velocities (GVs) are formed within the resonant cavity of the laser. The cross-phase modulation effect leads to the formation of a robust fast-GV compound (FGC), consisting of a partially coherent dissipative soliton bunch (PCDSB) and dispersion waves (DWs), while a conventional soliton (CS) and a narrow spectral pulse (NSP) form a slow-GV compound (SGC). Multiple SGCs can further interact to form an SGC loosely bound complex. These two types of compounds with different GVs continuously collide and exchange energy through the four-wave mixing (FWM) effect in the HNLF, promoting the annihilation, survival, and regeneration of the SGC complex. This exploration of interactions between asynchronous compounds broadens the study of soliton dynamics in multi-dimensions and offers insights for potential applications in areas such as high-throughput optical communication and optical computing.
Photonics Research
- Publication Date: May. 30, 2025
- Vol. 13, Issue 6, 1680 (2025)
Origin of SBS-induced mode distortion in high power narrow linewidth fiber amplifiers
Yu Wen, Chun Zhang, Yuan Zhu, Zixiang Gao, Xingchen Jiang, Rumao Tao, Qiuhui Chu, Qiang Shu, Fengyun Li, Haoyu Zhang, Honghuan Lin, Zhitao Peng, and Jianjun Wang
Stimulated Brillouin scattering (SBS)-induced mode distortion (MD) in high power narrow linewidth fiber amplifiers has been implemented, and the origin has been investigated from the aspect of the evolution of the optical spectrum, spatial beam profiles, and temporal-frequency domain characteristics. It is shown that, following the onset of the backward giant pulses generated by SBS, forward giant pulses were generated, which reached multi-kilowatt level peak power and triggered the onset of stimulated Raman scattering (SRS). After the onset of SRS, the beam quality starts to degrade, and the beam profiles deteriorate obviously. It reveals that the SBS-induced MD is a two-stage physical process: SBS-induced forward giant pulses trigger the SRS effect, and then the SRS effect causes the beam deterioration of the signal laser, which means that SRS is the origin of the MD observed after the onset of SBS. To the best of our knowledge, this is the first revelation of SBS-induced mode distortion in high power narrow linewidth fiber amplifiers, which can facilitate the in-depth understanding and effective suppression of the complicated mode evolution phenomena. Stimulated Brillouin scattering (SBS)-induced mode distortion (MD) in high power narrow linewidth fiber amplifiers has been implemented, and the origin has been investigated from the aspect of the evolution of the optical spectrum, spatial beam profiles, and temporal-frequency domain characteristics. It is shown that, following the onset of the backward giant pulses generated by SBS, forward giant pulses were generated, which reached multi-kilowatt level peak power and triggered the onset of stimulated Raman scattering (SRS). After the onset of SRS, the beam quality starts to degrade, and the beam profiles deteriorate obviously. It reveals that the SBS-induced MD is a two-stage physical process: SBS-induced forward giant pulses trigger the SRS effect, and then the SRS effect causes the beam deterioration of the signal laser, which means that SRS is the origin of the MD observed after the onset of SBS. To the best of our knowledge, this is the first revelation of SBS-induced mode distortion in high power narrow linewidth fiber amplifiers, which can facilitate the in-depth understanding and effective suppression of the complicated mode evolution phenomena.
Photonics Research
- Publication Date: May. 27, 2025
- Vol. 13, Issue 6, 1631 (2025)
Non-symmetrical vortex beam shaping in VECSEL laser arrays
Sopfy Karuseichyk, Ilan Audoin, Vishwa Pal, and Fabien Bretenaker
We propose and numerically test, to our knowledge, a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser (DVECSEL). The method is based on a phase-locking ring array of lasers created inside a degenerate cavity with a binary amplitude mask containing circular holes. The diffraction engineering of the mask profile allows for controlling the complex coupling between the lasers. The asymmetry between different lasers is introduced by varying the hole diameters corresponding to different lasers. Several examples of masks with non-uniform or uniform circular holes are investigated numerically and analytically to assess the impact of non-uniform complex coupling coefficients on the degeneracy between the vortex and anti-vortex steady states of the ring laser arrays. It is found that the in-phase solution always dominates irrespective of non-uniform masks. The only solution to make one particular vortex solution dominant over other possible steady-state solutions consists of imprinting the necessary phase shift among neighboring lasers in the argument of their coupling coefficients. We also investigate the role of the Henry factor inherent to the use of a semiconductor active medium in the probabilities to generate vortex solutions. Analytical calculations are performed to generalize a formula previously reported [Opt. Express30, 15648 (2022)OPEXFF1094-408710.1364/OE.456946], for the limiting Henry factor to cover the case of complex couplings. We propose and numerically test, to our knowledge, a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser (DVECSEL). The method is based on a phase-locking ring array of lasers created inside a degenerate cavity with a binary amplitude mask containing circular holes. The diffraction engineering of the mask profile allows for controlling the complex coupling between the lasers. The asymmetry between different lasers is introduced by varying the hole diameters corresponding to different lasers. Several examples of masks with non-uniform or uniform circular holes are investigated numerically and analytically to assess the impact of non-uniform complex coupling coefficients on the degeneracy between the vortex and anti-vortex steady states of the ring laser arrays. It is found that the in-phase solution always dominates irrespective of non-uniform masks. The only solution to make one particular vortex solution dominant over other possible steady-state solutions consists of imprinting the necessary phase shift among neighboring lasers in the argument of their coupling coefficients. We also investigate the role of the Henry factor inherent to the use of a semiconductor active medium in the probabilities to generate vortex solutions. Analytical calculations are performed to generalize a formula previously reported [Opt. Express30, 15648 (2022)OPEXFF1094-408710.1364/OE.456946], for the limiting Henry factor to cover the case of complex couplings.
Photonics Research
- Publication Date: May. 27, 2025
- Vol. 13, Issue 6, 1600 (2025)
Single-mode bending optofluidic waveguides and beam splitters in fused silica enabled by polarization-independent femtosecond-laser-assisted etching
Jianping Yu, Jian Xu, Jinxin Huang, Jianfang Chen, Jia Qi, and Ya Cheng
Bending optofluidic waveguides are essential for developing high-performance fluid-based photonic circuits and systems. The combination of femtosecond (fs)-laser-assisted etching of high-precision microchannels and vacuum-assisted liquid-core filling allows the controllable fabrication of low-loss optofluidic waveguides in fused silica. However, to form high-performance bending optofluidic waveguides in fused silica, facile fabrication of long, homogeneous microchannels with arbitrary shapes remains challenging due to the polarization-dependent limitations of conventional fs-laser-assisted etching. Here, we demonstrate the rational fabrication of homogeneous curved microchannels in fused silica using polarization-independent fs-laser-assisted etching enabled by a low-pulse-overlap scheme. An etching rate exceeding 350 μm/h can be reliably achieved at a pulse overlap of 10 pulses μm-1 regardless of the variation of the laser polarization. Highly interconnected nanocracks are observed along the laser writing direction in the laser-modified regions. Using the polarization-independent fs-laser-assisted etching combined with spatial beam shaping and carbon dioxide laser irradiation, uniform and smooth curved microchannels with centimeter lengths, flexible configurations, and nearly circular cross-sections are initially produced. Subsequently, single-mode bending optofluidic waveguides and beam splitters are created by filling tunable refractive index liquid-core solutions into the channels. The proposed method enables efficient processing of arbitrarily oriented homogeneous microchannels, paving the way for the development of large-scale, complex microfluidic photonic circuits. Bending optofluidic waveguides are essential for developing high-performance fluid-based photonic circuits and systems. The combination of femtosecond (fs)-laser-assisted etching of high-precision microchannels and vacuum-assisted liquid-core filling allows the controllable fabrication of low-loss optofluidic waveguides in fused silica. However, to form high-performance bending optofluidic waveguides in fused silica, facile fabrication of long, homogeneous microchannels with arbitrary shapes remains challenging due to the polarization-dependent limitations of conventional fs-laser-assisted etching. Here, we demonstrate the rational fabrication of homogeneous curved microchannels in fused silica using polarization-independent fs-laser-assisted etching enabled by a low-pulse-overlap scheme. An etching rate exceeding 350 μm/h can be reliably achieved at a pulse overlap of 10 pulses μm-1 regardless of the variation of the laser polarization. Highly interconnected nanocracks are observed along the laser writing direction in the laser-modified regions. Using the polarization-independent fs-laser-assisted etching combined with spatial beam shaping and carbon dioxide laser irradiation, uniform and smooth curved microchannels with centimeter lengths, flexible configurations, and nearly circular cross-sections are initially produced. Subsequently, single-mode bending optofluidic waveguides and beam splitters are created by filling tunable refractive index liquid-core solutions into the channels. The proposed method enables efficient processing of arbitrarily oriented homogeneous microchannels, paving the way for the development of large-scale, complex microfluidic photonic circuits.
Photonics Research
- Publication Date: May. 27, 2025
- Vol. 13, Issue 6, 1562 (2025)
All-fiber-structure high-power mid-infrared gas-filled hollow-core-fiber amplified spontaneous emission source
Weihua Song, Yu Wen, Qian Zhang, Xin Zhang, and Pu Wang
Hollow-core-fiber (HCF) gas lasers (GLs) have garnered significant interest as a novel approach for generating mid-infrared lasers, owing to their inherent benefits of rich emission wavelength, high beam quality, and high output power potential. However, they are mostly achieved by a free-space coupling structure, which has a major drawback of being prone to vibrations and other environmental variations. Here, we devise and implement an all-fiber-structure gas-filled HCF amplified spontaneous emission (ASE) source at 3.1 μm based on the reverse tapering and angle-cleaved fusion splicing techniques. By optimizing the C2H2 gas pressure, a maximum mid-infrared output power of 6.59 W was obtained, corresponding to a slope efficiency of 19.74% and near-diffraction-limited beam qualities of Mx2=1.03 and My2=1.06. Furthermore, with a similar all-fiber configuration, a CO2-filled HCF ASE source at 4.3 μm with output power exceeding 1.4 W was generated. To the best of our knowledge, the proposed all-fiber-structure HCF gas light source demonstrates the longest wavelength and highest power reported to date. The development of mid-infrared HCF gas light sources in an all-fiber configuration represents a significant step toward miniaturized HCF lasers, which hold promise as powerful new tools for application in laser medicine, space communication, and other scientific research. Hollow-core-fiber (HCF) gas lasers (GLs) have garnered significant interest as a novel approach for generating mid-infrared lasers, owing to their inherent benefits of rich emission wavelength, high beam quality, and high output power potential. However, they are mostly achieved by a free-space coupling structure, which has a major drawback of being prone to vibrations and other environmental variations. Here, we devise and implement an all-fiber-structure gas-filled HCF amplified spontaneous emission (ASE) source at 3.1 μm based on the reverse tapering and angle-cleaved fusion splicing techniques. By optimizing the C2H2 gas pressure, a maximum mid-infrared output power of 6.59 W was obtained, corresponding to a slope efficiency of 19.74% and near-diffraction-limited beam qualities of Mx2=1.03 and My2=1.06. Furthermore, with a similar all-fiber configuration, a CO2-filled HCF ASE source at 4.3 μm with output power exceeding 1.4 W was generated. To the best of our knowledge, the proposed all-fiber-structure HCF gas light source demonstrates the longest wavelength and highest power reported to date. The development of mid-infrared HCF gas light sources in an all-fiber configuration represents a significant step toward miniaturized HCF lasers, which hold promise as powerful new tools for application in laser medicine, space communication, and other scientific research.
Photonics Research
- Publication Date: Apr. 21, 2025
- Vol. 13, Issue 5, 1137 (2025)
Unveiling intracavity soliton evolution dynamics of a mode-locked fiber laser along the dispersion map
Jiarun Zhang, Tianchang Lu, Xiankun Yao, Yusheng Zhang, Dong Mao, Chao Zeng, Xiang Hao, Longhua Tang, Yudong Cui, Cuifang Kuang, and Xu Liu
Mode-locked fiber lasers are excellent platforms for soliton generation. Solitons exhibit distinct distribution and evolution characteristics depending on the net dispersion of the laser cavity. Here we propose an experimental scheme to reconstruct the intracavity dynamics of solitons within a mode-locked fiber laser. The proposed scheme is facilitated by disposing multiple output ports at different positions throughout the cavity, thereby enabling in-depth observation and manipulation of soliton evolution along the dispersion map. The experimental results verify corresponding simulations and explain some phenomena from the perspective of soliton evolution. Our results offer a pathway for comprehensive analyses of intracavity pulse dynamics, fostering advancements in nonlinear and ultrafast optics. Mode-locked fiber lasers are excellent platforms for soliton generation. Solitons exhibit distinct distribution and evolution characteristics depending on the net dispersion of the laser cavity. Here we propose an experimental scheme to reconstruct the intracavity dynamics of solitons within a mode-locked fiber laser. The proposed scheme is facilitated by disposing multiple output ports at different positions throughout the cavity, thereby enabling in-depth observation and manipulation of soliton evolution along the dispersion map. The experimental results verify corresponding simulations and explain some phenomena from the perspective of soliton evolution. Our results offer a pathway for comprehensive analyses of intracavity pulse dynamics, fostering advancements in nonlinear and ultrafast optics.
Photonics Research
- Publication Date: Apr. 21, 2025
- Vol. 13, Issue 5, 1130 (2025)
All-solid-state miniature laser gyroscope based on a single monolithic non-planar ring oscillator|Editors' Pick
Danqing Liu, Changlei Guo, Chunzhao Ma, Weitong Fan, Xuezhen Gong, Zhen Zhang, Wenxun Li, Jie Xu, Kui Liu, and Hsien-Chi Yeh
He-Ne gaseous ring-laser gyroscopes (RLGs) have brought great breakthroughs in numbers of fields such as inertial navigation and attitude control in the past 50 years. However, their counterparts of all-solid-state, active RLGs have been far behind even though they have a few indispensable advantages. Here, we propose and demonstrate an all-solid-state, active RLG based on a millimeter-sized, single monolithic non-planar ring oscillator (NPRO) with a gain medium of Nd:YAG crystal or Nd-glass. The clockwise (CW) and counter-clockwise (CCW) laser modes in NPRO are simultaneously initiated under a regime of laser feedback interferometry, whose nonzero frequency difference intrinsically formats the single monolithic NPRO working as a Sagnac laser gyroscope without a noticeable lock-in effect. The higher wavefront distortion in NPRO samples is revealed to introduce less mode competition (higher beat frequency stability) between the two laser modes, which is a precondition to build the NPRO gyroscope. Under a free-running condition, the NPRO gyroscope typically has a bias instability of 31.3 deg/h and an angle random walk of 0.22 deg/h with a scale factor of 38.3 Hz/(deg s-1), and the instability is mainly caused by the magnetic noise at present. The NPRO gyroscope can be enclosed in a centimeter-sized package, with a power consumption below 0.7 W and a mass under 20 g. Moreover, the stability performance can be further improved by NPRO design and active noise suppression in the future. Such compact, low-power-consumed, and highly stable RLGs may find important applications in aerospace, defense, and industry. He-Ne gaseous ring-laser gyroscopes (RLGs) have brought great breakthroughs in numbers of fields such as inertial navigation and attitude control in the past 50 years. However, their counterparts of all-solid-state, active RLGs have been far behind even though they have a few indispensable advantages. Here, we propose and demonstrate an all-solid-state, active RLG based on a millimeter-sized, single monolithic non-planar ring oscillator (NPRO) with a gain medium of Nd:YAG crystal or Nd-glass. The clockwise (CW) and counter-clockwise (CCW) laser modes in NPRO are simultaneously initiated under a regime of laser feedback interferometry, whose nonzero frequency difference intrinsically formats the single monolithic NPRO working as a Sagnac laser gyroscope without a noticeable lock-in effect. The higher wavefront distortion in NPRO samples is revealed to introduce less mode competition (higher beat frequency stability) between the two laser modes, which is a precondition to build the NPRO gyroscope. Under a free-running condition, the NPRO gyroscope typically has a bias instability of 31.3 deg/h and an angle random walk of 0.22 deg/h with a scale factor of 38.3 Hz/(deg s-1), and the instability is mainly caused by the magnetic noise at present. The NPRO gyroscope can be enclosed in a centimeter-sized package, with a power consumption below 0.7 W and a mass under 20 g. Moreover, the stability performance can be further improved by NPRO design and active noise suppression in the future. Such compact, low-power-consumed, and highly stable RLGs may find important applications in aerospace, defense, and industry.
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 897 (2025)
Self-injection locked laser via a hollow-core fiber Fabry–Perot resonator
Zitong Feng, Meng Ding, Mateˇj Komanec, Stanislav Zvánovec, Ailing Zhong, Francesco Poletti, Giuseppe Marra, and Radan Slavík
In a hollow-core fiber (HCF), light propagates through an air/vacuum core rather than a solid material, resulting in a low thermo-optic coefficient and ability to handle high powers. Here, we demonstrate a laser locked to a hollow-core fiber reference, which thanks to the low HCF thermal sensitivity, shows long-term stability an order of magnitude better than compact commercially available low-noise lasers. The laser frequency variation within ±600 kHz was measured over 50 h. The stability of our proof-of-concept laser is ensured via a strong self-injection ratio of -15 dB, enabled by the high-power handling and low loss of the hollow-core fiber’s resonator. Moreover, our results show appealing performance parameters, including a fractional frequency stability of 4×10-13 at 1 s averaging time and a Lorentzian component of the linewidth of 0.2 Hz. In a hollow-core fiber (HCF), light propagates through an air/vacuum core rather than a solid material, resulting in a low thermo-optic coefficient and ability to handle high powers. Here, we demonstrate a laser locked to a hollow-core fiber reference, which thanks to the low HCF thermal sensitivity, shows long-term stability an order of magnitude better than compact commercially available low-noise lasers. The laser frequency variation within ±600 kHz was measured over 50 h. The stability of our proof-of-concept laser is ensured via a strong self-injection ratio of -15 dB, enabled by the high-power handling and low loss of the hollow-core fiber’s resonator. Moreover, our results show appealing performance parameters, including a fractional frequency stability of 4×10-13 at 1 s averaging time and a Lorentzian component of the linewidth of 0.2 Hz.
Photonics Research
- Publication Date: Feb. 24, 2025
- Vol. 13, Issue 3, 611 (2025)
Dispersion step tuning fiber laser based on a Mach–Zehnder interferometer
Duidui Li, Guolu Yin, Lei Gao, Ligang Huang, Huafeng Lu, and Tao Zhu
This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach–Zehnder interferometer, enabling a transition from continuous wavelength sweeping to wavelength-stepped sweeping. A comprehensive investigation of this laser is conducted, wherein different modulation schemes are employed to dynamically compare the switching mode, static-sweeping mode, and sweeping mode; the absence of mode hopping in the sweeping mode of the laser is verified. However, it is observed during experiments that the wavelength always remains stationary for a long time during the initiation of sweeping and change in sweeping direction, exhibiting latency compared to the modulation frequency variations. Through a simplistic modeling analysis of the composite cavity, it is revealed that the detuned state of the sub-cavity plays a critical role in the stable operation of the laser. Subsequently, simulation verification using the Ginzburg–Landau equation supports this observation. Additionally, compared to dispersion-tuned swept lasers, not only the linewidth significantly is narrowed in the proposed laser, but it also demonstrates enhanced stability during the sweeping process. This study provides, to our knowledge, a new laser source for ultra-fast optical imaging, ranging, and sensing applications, and presents novel methods and theoretical models for linewidth compression in swept lasers. This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach–Zehnder interferometer, enabling a transition from continuous wavelength sweeping to wavelength-stepped sweeping. A comprehensive investigation of this laser is conducted, wherein different modulation schemes are employed to dynamically compare the switching mode, static-sweeping mode, and sweeping mode; the absence of mode hopping in the sweeping mode of the laser is verified. However, it is observed during experiments that the wavelength always remains stationary for a long time during the initiation of sweeping and change in sweeping direction, exhibiting latency compared to the modulation frequency variations. Through a simplistic modeling analysis of the composite cavity, it is revealed that the detuned state of the sub-cavity plays a critical role in the stable operation of the laser. Subsequently, simulation verification using the Ginzburg–Landau equation supports this observation. Additionally, compared to dispersion-tuned swept lasers, not only the linewidth significantly is narrowed in the proposed laser, but it also demonstrates enhanced stability during the sweeping process. This study provides, to our knowledge, a new laser source for ultra-fast optical imaging, ranging, and sensing applications, and presents novel methods and theoretical models for linewidth compression in swept lasers.
Photonics Research
- Publication Date: Feb. 18, 2025
- Vol. 13, Issue 3, 604 (2025)
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