<title>Harmonic passive mode-locked fiber lasers with long-distance modulation of loss and refractive index</title>

Small All-Range Lidar for Asteroid and Comet Core Missions

Sensors ◽

10.3390/s21093081 ◽

2021 ◽

Vol 21 (9) ◽

pp. 3081

Author(s):

Xiaoli Sun ◽

Daniel R. Cremons ◽

Erwan Mazarico ◽

Guangning Yang ◽

James B. Abshire ◽

...

Keyword(s):

Fiber Lasers ◽

Dynamic Range ◽

Photon Counting ◽

Avalanche Photodiode ◽

Integration Time ◽

Sample Collection ◽

Long Distance ◽

Linear Mode ◽

Internal Gain ◽

Pseudo Noise

We report the development of a new type of space lidar specifically designed for missions to small planetary bodies for both topographic mapping and support of sample collection or landing. The instrument is designed to have a wide dynamic range with several operation modes for different mission phases. The laser transmitter consists of a fiber laser that is intensity modulated with a return-to-zero pseudo-noise (RZPN) code. The receiver detects the coded pulse-train by correlating the detected signal with the RZPN kernel. Unlike regular pseudo noise (PN) lidars, the RZPN kernel is set to zero outside laser firing windows, which removes most of the background noise over the receiver integration time. This technique enables the use of low peak-power but high pulse-rate lasers, such as fiber lasers, for long-distance ranging without aliasing. The laser power and the internal gain of the detector can both be adjusted to give a wide measurement dynamic range. The laser modulation code pattern can also be reconfigured in orbit to optimize measurements to different measurement environments. The receiver uses a multi-pixel linear mode photon-counting HgCdTe avalanche photodiode (APD) array with near quantum limited sensitivity at near to mid infrared wavelengths where many fiber lasers and diode lasers operate. The instrument is modular and versatile and can be built mostly with components developed by the optical communication industry.

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All-solution doping technique for high power fiber lasers - refractive index influence in the vicinity of Al:P = 1:1

Laser Congress 2017 (ASSL, LAC) ◽

10.1364/assl.2017.atu5a.6 ◽

2017 ◽

Author(s):

Stefan Kuhn ◽

Sigrun Hein ◽

Christian Hupel ◽

Johannes Nold ◽

Nicoletta Haarlammert ◽

...

Keyword(s):

Refractive Index ◽

High Power ◽

Fiber Lasers ◽

Doping Technique ◽

Solution Doping

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Deterministic Dynamics of Solitons in Passive Mode-Locked Fiber Lasers

Nonlinear Optical Systems ◽

10.1201/b11698-9 ◽

2012 ◽

pp. 214-263

Keyword(s):

Fiber Lasers ◽

Passive Mode ◽

Deterministic Dynamics

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Drift Reduction of a 4-DOF Measurement System Caused by Unstable Air Refractive Index

Sensors ◽

10.3390/s20216329 ◽

2020 ◽

Vol 20 (21) ◽

pp. 6329

Author(s):

Ruijun Li ◽

Yongjun Wang ◽

Pan Tao ◽

Rongjun Cheng ◽

Zhenying Cheng ◽

...

Keyword(s):

Refractive Index ◽

Laser Beam ◽

Measurement System ◽

Degrees Of Freedom ◽

Cost Effective ◽

Control Mode ◽

Detection Accuracy ◽

Long Distance ◽

Cost Effective Method ◽

Novel Method

Laser beam drift greatly influences the accuracy of a four degrees of freedom (4-DOF) measurement system during the detection of machine tool errors, especially for long-distance measurement. A novel method was proposed using bellows to serve as a laser beam shield and air pumps to stabilize the refractive index of air. The inner diameter of the bellows and the control mode of the pumps were optimized through theoretical analysis and simulation. An experimental setup was established to verify the feasibility of the method under the temperature interference condition. The results indicated that the position stability of the laser beam spot can be improved by more than 79% under the action of pumping and inflating. The proposed scheme provides a cost-effective method to reduce the laser beam drift, which can be applied to improve the detection accuracy of a 4-DOF measurement system.

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Study on the height distribution of atmospheric nonlinear refractive index with a theoretical calculation model

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s0218863518500443 ◽

2018 ◽

Vol 27 (04) ◽

pp. 1850044

Author(s):

QingWei Zeng ◽

Lei Liu ◽

TaiChang Gao ◽

Ming Chen ◽

Qi Wang ◽

...

Keyword(s):

Refractive Index ◽

Nonlinear Refractive Index ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Ultrashort Laser Pulses ◽

Lower Atmosphere ◽

Nonlinear Propagation ◽

Accurate Estimation ◽

Height Distribution ◽

Long Distance

The crucial role of nonlinear propagation effects in the self-guiding of femtosecond laser pulses required accurate representation of nonlinearities to describe them. In this paper, an improved theoretical model has been proposed to study the height distribution of the atmospheric nonlinear refractive index. The results show that the revised model obviously improves accurate estimation of nonlinear index at the long wavelength band. Based on the model, we also found the atmospheric nonlinear refractive index differs much from the lower atmosphere to the upper atmosphere. Our results are essential for engineering applications based on the long-distance ultrashort laser pulses’ transmission in diverse atmosphere.

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