External Modulation Method for Generating Accurate Linear Optical FMCW

Lyu, Yingkai; Yang, Tianxin; Lu, Zhaoyu; Guo, Chunyu; Ge, Chunfeng; Wang, Zhaoying; Jia, Dongfang; Yin, Huabing

doi:10.1109/lpt.2017.2736561

Cited by 9 publications

(3 citation statements)

References 11 publications

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“…Compared with combination of a static continuous-wave Laser and external modulator, direct modulating injection current to the semiconductor Lasers (SCLs) provides a low cost, simple and integrable way to acquire the FMCW light source. 1,11,16,17 However, there are three challenges associated with this scheme. [18][19][20][21] First, the direct modulation typically generates unwanted nonlinearity of frequency sweeping without pre-distortion to the *Tianxin Yang: E-mail: tyang@tju.edu.cn injection current.…”

Section: Introductionmentioning

confidence: 99%

High sweeping linearity and optical intensity control of broadband FMCW laser source generation for 4D imaging LiDAR

Yang,

Zeng

et al. 2024

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

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Frequency-modulated continuous-wave (FMCW) light source is a key component in light detection and ranging (LiDAR) systems with high sensitivity and precision. In this paper, we report a triangular-waveform broadband FMCW light source based on pre-distorted injecting current of a distributed feedback (DFB) laser diode and a feedback control loop for keeping optical intensity constant during the frequency sweeping. A pre-distorted injecting current waveform generated by adaptive pre-distortion method is used to drive a DFB laser to generate FMCW light source. After 100 iterations, we achieved the effective frequency sweeping excursion about 31 GHz within 90% region of interest. The frequency sweeping nonlinearities of the down-and up-ramp were 3.10 × 10 −9 and 5.32×10 −9 , respectively. The corresponding relative nonlinearities for down-and up-ramp were 0.00157% and 0.00206%. Due to the modulation of injecting current, the lasing optical intensity of DFB underwent undesired intensity modulation. To achieve constant optical intensity, we utilized a feedback control loop in combination with a Mach-Zehnder interferometer. By comparing the beat-note with and without feedback control loop, the intensity of waveform in the time domain was obviously corrected, which could further improve the ranging resolution from 4.59 mm to 4.30 mm.

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Section: Introductionmentioning

confidence: 99%

High sweeping linearity and optical intensity control of broadband FMCW laser source generation for 4D imaging LiDAR

Yang,

Zeng

et al. 2024

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

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“…Being free of the relaxation oscillation, external modulation methods can maintain the high coherence of laser sources no matter how fast the swept rates are. A typical external modulator is a dual-parallel Mach-Zehnder modulator (DPMZM) which operates in single sideband (SSB) state 5,8 . In our previous work 6 , we have generated the FMCW light source with frequency excursion of 200 GHz and repetition period of 5.5 μs based on the DPMZM system.…”

Section: Introductionmentioning

confidence: 99%

Technology of 4D imaging LiDARs

Yang,

Xiao

2024

Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications XVII

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First, the concept of 4D imaging is introduced, and for imaging application LiDAR would replace the role of Radar because of broad bandwidth in optical domain. Then, two different types of LiDARs, i.e., ToF LiDAR and FMCW LiDAR, are compared in the view of aspect in creating high quality 4D imaging data. At last, the FMCW LiDAR is selected for the imaging applications and recent experimental results are presented.

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“…An ultrafast linear frequency modulated continuous-wave (FMCW) laser in which the frequency changes continuously with time in a periodic fashion while its intensity is kept constant is extensively required in various applications, such as measurements for absolute distance, speed, and vibration [ 1 , 2 , 3 ], light detection and ranging (LiDAR) [ 4 , 5 ], coherent optical spectrum analyzer (COSA) [ 6 , 7 , 8 ], optical coherence tomography (OCT) [ 9 , 10 , 11 ], micro-cavity dispersion measurement [ 12 ], satellite formation flying [ 13 ], precision manufacturing [ 14 ], and so on. Many applications ideally need a linear FMCW light source with broad frequency sweep excursion, narrow instantaneous linewidth, fast frequency sweep rate, and excellent frequency modulation linearity (without mode-hopping) [ 15 , 16 , 17 ], so that a FMCW LiDAR could detect remote targets at ultrafast scanning rates with ultrahigh range resolution compared to its counterpart, a time-of-flight (ToF) LiDAR.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser

Yang

Wang

et al. 2020

Sensors

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Ultrafast linear frequency modulated continuous-wave (FMCW) lasers are a special category of CW lasers. The linear FMCW laser is the light source for many sensing applications, especially for light detection and ranging (LiDAR). However, systems for the generation of high quality linear FMCW light are limited and diverse in terms of technical approaches and mechanisms. Due to a lack of characterization methods for linear FMCW lasers, it is difficult to compare and judge the generation systems in the same category. We propose a novel scheme for measuring the mapping relationship between instantaneous frequency and time of a FMCW laser based on a modified coherent optical spectrum analyzer (COSA) and digital signal processing (DSP) method. Our method has the potential to measure the instantaneous frequency of a FMCW laser at an unlimited sweep rate. In this paper, we demonstrate how to use this new method to precisely measure a FMCW laser at a large fast sweep rate of 5000 THz/s by both simulation and experiments. We find experimentally that the uncertainty of this method is less than 100 kHz and can be improved further if a frequency feedback servo system is introduced to stabilize the local CW laser.

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External Modulation Method for Generating Accurate Linear Optical FMCW

Cited by 9 publications

References 11 publications

High sweeping linearity and optical intensity control of broadband FMCW laser source generation for 4D imaging LiDAR

High sweeping linearity and optical intensity control of broadband FMCW laser source generation for 4D imaging LiDAR

Technology of 4D imaging LiDARs

A Novel Method of Measuring Instantaneous Frequency of an Ultrafast Frequency Modulated Continuous-Wave Laser

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