All semiconductor laser Doppler anemometer at 155 μm

Hansen, René Skov; Pedersen, Christian

doi:10.1364/oe.16.018288

Cited by 31 publications

(25 citation statements)

References 8 publications

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“…Improvement in lidar technology -new, cheaper solidstate lasers for coherent detection lidars with integrated optical amplification are being developed and tested (Hansen and Pedersen, 2008;Rodrigo and Pedersen, 2008). These may greatly expand the use of lidars for wind measurements, but they are not specifically tailored for turbulence measurements.…”

Section: Summary and Discussionmentioning

confidence: 99%

A review of turbulence measurements using ground-based wind lidars

Sathe¹,

Mann²

2013

Atmos. Meas. Tech.

153

117

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Abstract.A review of turbulence measurements using ground-based wind lidars is carried out. Works performed in the last 30 yr, i.e., from 1972-2012 are analyzed. More than 80 % of the work has been carried out in the last 15 yr, i.e., from 1997-2012. New algorithms to process the raw lidar data were pioneered in the first 15 yr, i.e., from 1972-1997, when standard techniques could not be used to measure turbulence. Obtaining unfiltered turbulence statistics from the large probe volume of the lidars has been and still remains the most challenging aspect. Until now, most of the processing algorithms that have been developed have shown that by combining an isotropic turbulence model with raw lidar measurements, we can obtain unfiltered statistics. We believe that an anisotropic turbulence model will provide a more realistic measure of turbulence statistics. Future development in algorithms will depend on whether the unfiltered statistics can be obtained without the aid of any turbulence model. With the tremendous growth of the wind energy sector, we expect that lidars will be used for turbulence measurements much more than ever before.

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Section: Summary and Discussionmentioning

confidence: 99%

A review of turbulence measurements using ground-based wind lidars

Sathe¹,

Mann²

2013

Atmos. Meas. Tech.

153

117

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“…The potential of laser based wind sensors in industrial applications, e.g. in wind energy industry, has been greatly enhanced by the use of cost-efficient semiconductor laser sources operating at 1.5 μm [1,2]. Previously, we have improved our diode laser based lidar wind sensor by incorporating an electronically controlled liquid-crystal retarder (LCR) as means to switch the beam direction between two lines-ofsight (LOS) [3].…”

Section: Introductionmentioning

confidence: 99%

Eye-safe diode laser Doppler lidar with a MEMS beam-scanner

Hu¹,

Pedersen²,

Rodrigo³

2016

Opt. Express

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We present a novel Doppler lidar that employs a cw diode laser operating at 1.5 μm and a micro-electro-mechanical-system scanning mirror (MEMS-SM). In this work, two functionalities of the lidar system are demonstrated. Firstly, we describe the capability to effectively steer the lidar probe beam to multiple optical transceivers along separate lines-ofsight. The beam steering functionality is demonstrated using four lines-ofsight -each at an angle of 18° with respect to their symmetry axis. Secondly, we demonstrate the ability to spatially dither the beam focus to reduce the mean irradiance at the probing distance (R = 60 m) of each lineof-sight -relevant for meeting eye-safety requirements. The switching time of the MEMS-SM is measured to be in the order of a few milliseconds. Time-shared (0.25 s per line-of-sight) radial wind speed measurements at 50 Hz data rate are experimentally demonstrated. Spatial dithering of the beam focus is also implemented using a spiral scan trajectory resulting in a 16 dB reduction of beam focus mean irradiance.

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“…Since the signal reflected by the aerosols is extremely weak, high output power is essential to obtain sufficient backscattered light for the detection. In addition, the optimum Doppler signal is achieved when the intensity distribution of the laser is Gaussian [17]; therefore a high beam quality is required. The first all-semiconductor wind lidar was demonstrated in 2008 by Hansen and coworkers [17].…”

Section: Motivationmentioning

confidence: 99%

“…In addition, the optimum Doppler signal is achieved when the intensity distribution of the laser is Gaussian [17]; therefore a high beam quality is required. The first all-semiconductor wind lidar was demonstrated in 2008 by Hansen and coworkers [17]. They reported wind speed measurements within a distance range of 10 to 200 meters with a typical signal to noise ratio of 9 dB at 45 meters.…”

Section: Motivationmentioning

confidence: 99%

“…At the eye-safe wavelength close to 1.5 µm, the QPC lasers company [92] reported the fabrication of MOPA devices exceeding 1 W of output power [93]. Using these commercial MOPA, Hansen and coworkers demonstrated the first all-semiconductor doppler anemometer for wind speed determination [17]. Our group at UPM also demonstrated the generation of 100 ps wide pulses with peak power up to 2.7 W at 1 GHz by gain-switching [39].…”

Section: High Brightness Laser Diodesmentioning

confidence: 99%

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Emission characteristics of 1.5 um monolithically integrated master oscillator power amplifiers

Suárez¹,

Fernánda²

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The present work is a study of the emission characteristics of monolithic semiconductor Master Oscillator Power Amplifiers (MOPAs) relevant for their use in applications requiring simultaneously high brightness and high spectral purity semiconductor laser sources. Two types of laser devices with wavelengths ranging between 1540 nm and 1580 nm have been studied: Commercial two-section MOPAs and three-section MOPAs specially designed for their use as optical sources for Differential Absorption LIDAR. The spectral analysis of the behavior of the two-section MOPAs revealed the occurrence of undesired spectral instabilities in large ranges of driving conditions precluding their use in applications requiring stable and narrow linewidth emission. A detailed experimental analysis of the stable and unstable emission regimens has been complemented with a theoretical analysis using a Travelling Wave model. From both approaches the instabilities have been attributed to dynamic effects induced by the optical feed-back allowed by the unavoidable residual reflectivity of the front facet and mediated by self-and cross-heating effects. The three-section MOPAs have been demonstrated to be free of spectral instabilities in a large range of driving conditions. The operation of these devices under the modulation conditions required for the intended application has been demonstrated. Their emission characteristics under modulation have been analyzed paying special attention to the modulation induced spectral broadening. Evidence of a frequency modulation contribution to the broadening has been shown. The frequency modulation induced by the modulation amplitude has been attributed to the refractive index changes induced by the carrier density modulation, induced in turn by the modulating current.The work is structured in 6 chapters. In the introductory Chapter 1 the work is motivated and framed in the research line of the group. The potential of MOPAs for high brightness applications is illustrated in the case of three applications: free space optical communications, wind Lidar and Lidar for remote sensing of atmospheric gases. In Chapter 2 the main ingredients on laser diodes necessary for the proper understanding of the rest of the work are briefly summarized. The chapter includes a brief description of two concepts for increasing the brightness of semiconductor sources: tapered lasers and monolithically integrated MOPAs. A review of the state of the art in integrated semiconductor MOPAs is also included.The details of the two-section straight MOPAs and three-section bent MOPAs investigated in this work as well as a description of the experimental techniques used for their characterization are provided in Chapter 3. Specific relevance is given to the description of those set-ups and experimental techniques that were implemented or developed as a part of this work, such as the set-up for driving unmounted multi-section lasers and systematically recording the maps of the optical and Radio-Frequency (RF) spectra, the implementa...

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All semiconductor laser Doppler anemometer at 155 μm

Cited by 31 publications

References 8 publications

A review of turbulence measurements using ground-based wind lidars

A review of turbulence measurements using ground-based wind lidars

Eye-safe diode laser Doppler lidar with a MEMS beam-scanner

Emission characteristics of 1.5 um monolithically integrated master oscillator power amplifiers

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