Gaëlle Lucas-Leclin

• PhD
• Professor (Associate) at Institut d'Optique Graduate School

Acousto-optic imaging (AOI) of absorbing objects embedded in highly scattering media remains challenging, since the detectable signal suitable for image reconstruction is weak. To increase the detected signals to a level required by live biological applications, we designed a high-peak-power quasi-continuous laser source based on the coherent combi...

We demonstrate the coherent combination of two microsecond-pulse semiconductor amplifiers for water vapor differential absorption lidar (DIAL) applications. The combined pulse energy reached 10.3 µJ with combining efficiencies above 82% ± 5%.

The requirements for coherent combination of high power GaAs-based single-pass tapered amplifiers are studied. Changes to the epitaxial layer structure are shown to bring higher beam quality and hence improved combining efficiency for one fixed device geometry. Specifically, structures with large vertical near field and low wave-guiding from the ac...

In this chapter, high-power direct diode laser systems are becoming more and more attractive for industrial applications where they are not limited anymore to the pumping of solid-state lasers and fibres. Nonetheless, the highest power emitted from a single laser chip is typically below 20 W for a broad area element in the near infrared, and even b...

We demonstrate coherent beam combining of four high brightness tapered amplifiers in pulsed, quasi continuous wave (QCW) operation, seeded by a 976 nm laser diode. The maximum power of 22.7 W was achieved with > 64% combining efficiency in a close to diffraction limited beam. We discuss turn-on dynamics of tapered amplifiers operated in pulsed mode...

Coherent beam combining (CBC) of high brightness tapered amplifiers (TPAs) is a promising approach for the development of high power semiconductor laser sources with excellent beam quality and offers a pathway to future direct diode high brightness system. Operation of the amplifiers in quasi continuous wave (QCW) mode allows to overcome the therma...

We report on a coherent beam combination of three high-brightness tapered amplifiers, which are seeded by a single-frequency laser at λ = 976 nm in a simple architecture with efficiently cooled emitters. The maximal combined power of 12.9 W is achieved at a combining efficiency of > 65%, which is limited by the amplifiers’ intrinsic beam quality. T...

We demonstrate a high-brightness laser module based on the coherent combination of three tapered semiconductor amplifiers, with a power > 12 W. The infrared beam is converted into the visible by second-harmonic generation in a PPLN crystal with a power up to 2 W limited by thermal effects.

We demonstrate a rear-side phase-locking architecture with two high-brightness diode lasers. This technique is based on the passive phase-locking of emitters in an external cavity on their rear facet, and their coherent combination on the front facet. Two high-brightness high-power tapered laser diodes are coherently combined using a Michelson-base...

We describe a new coherent beam combining architecture based on passive phase locking of emitters in an extended cavity on the rear facet and their coherent combination on the front facet. This rear-side technique provides strong optical feedback for phase locking while maintaining a high electrical-to-optical efficiency. Two high-brightness high-p...

We demonstrate a rear-side phase-locking architecture with two high-brightness diode lasers. This technique is based on the passive phase-locking of emitters in an external cavity on their rear facet, and their coherent combination on the front facet. Two high-brightness high-power tapered laser diodes are coherently combined using a Michelson-base...

We describe a new coherent beam combining architecture based on passive phase-locking of two laser diodes in a Michelson external cavity on their rear facet, and their coherent combination on the front facet. As a proof-of-principle, two ridge lasers have been coherently combined with >90 % efficiency. The phase-locking range, and the resistance of...

We describe a new coherent beam combining architecture based on passive phase-locking of two laser diodes in a Michelson external cavity on their rear facet, and their coherent combination on the front facet. As a proof-of-principle, two ridge lasers have been coherently combined with >90 % efficiency. The phase-locking range, and the resistance of...

We evaluate a dual-frequency and dual-polarization optically-pumped semiconductor laser emitting at 852 nm as a new laser source for compact atomic clocks based on the coherent population trapping (CPT) technique. The frequency difference between the laser modes is tunable to 9.2 GHz corresponding to the ground state hyperfine-split of Cs. Impact o...

Déposants : CNRS et Institut d'Optique Graduate School

Talk given at Leibniz Institut / Ferdinand Braun (Berlin)

We report the dual-frequency and dual-polarization emission of an optically-pumped vertical external-cavity semiconductor laser. Our laser source provides a high-purity optically-carried RF signal tunable in the GHz range, and is specifically designed for the coherent population trapping (CPT) of Cs atoms in compact atomic clocks. The laser spectru...

Coherent population trapping (CPT) of metal-alkali atoms is an interesting technique for the development of compact atomic frequency references; it relies on the excitation of the atoms by two phase-coherent laser fields. We describe the design and operation of an innovating dual-frequency laser source dedicated to Cs CPT atomic clocks, based on th...

Coherent population trapping (CPT) of metal-alkali atoms is an interesting technique for the development of compact atomic frequency references; it relies on the excitation of the atoms by two phase-coherent laser fields. We describe the design and operation of an innovating dual-frequency laser source dedicated to Cs CPT atomic clocks, based on th...

Thermal saturation of VECSELs emission properties stays a major issue in those applications, requiring a high precision on the chip emission wavelength (such as atomic clocks experiments). In this paper we analyze the possibility to reduce the thermal resistance of the semiconductor chip emitting at 850nm by means of substrate substitution method....

Coherent population trapping (CPT) is an interesting technique for the development of compact atomic frequency references. We describe an innovating laser source for the production of the two cross-polarized coherent laser fields which are necessary in CPT-based atomic clocks. It relies on the dual-frequency and dual-polarization operation of an op...

We demonstrate a tunable high-purity microwave signal generation from a cross- polarized dual-frequency diode-pumped vertical external-cavity semiconductor laser operating at 852 nm for the coherent population trapping of cesium atoms in compact atomic frequency references.

We report on the EC BRIDLE project, which aims to develop a direct diode laser source (with more than 2kW of output power from a 100µm diameter optical fibre and an efficiency of 40%) for industrial sheet metal cutting applications. The project concepts are explored, from novel tailored diode laser mini-bars to advanced beam combining architectures...

We describe the dual-frequency operation of an optically-pumped vertical external cavity semiconductor laser (VECSEL) stabilized onto an Cs atomic transition. It is based on the simultaneous emission of two cross-polarized adjacent longitudinal modes inside the same laser cavity, which provides a strong correlation between the two laser lines. The...

Poster The Celebration of the 50th Anniversary of the Laser Diode University of Warwick, UK

We present the dual-frequency emission of a diode-pumped vertical external-cavity semiconductor laser at 852 nm dedicated to coherent population trapping experiments. With a compact cavity more than 10mW is demonstrated in each polarization, with a frequency difference in the GHz range. One polarization has been stabilized on an atomic transition

We describe the dual-frequency and dual-polarization emission of a diode-pumped vertical external-cavity semiconductor laser at 852 nm dedicated to the coherent population trapping of cesium atoms. The output power reaches ${\sim}{\rm 20}~{\rm mW}$ on each frequency, with a frequency difference in the gigahertz range.

We present in this work the study of a short vertical external cavity semiconductor laser in single longitudinal operation at 852 nm without intracavity elements. Two different configurations were studied, a plane-plane configuration, stabilized by the thermal lens and a plane-concave configuration. The influence of the output coupler transmission...

An external cavity with a binary phase grating has been developed to achieve the coherent beam addition of five quantum-cascade lasers emitting at 4.65 μm. The combining of these five emitters is achieved by a binary phase grating or Dammann grating able to separate an incident beam into five beams of equal intensities with a 75% efficiency. A CW o...

An external cavity using a binary phase grating has been developed to achieve coherent combining of five quantum-cascade lasers emitting at 4.65 μm . The grating phase profile is designed to combine five beams of equal intensities into a single beam with a good efficiency ( ∼ 75 % ). The performances of this cavity concerning output power, stabilit...

Nous décrivons l'émission simultanée en phase sur deux fréquences optiques polarisées perpendiculairement d'un laser à semiconducteur en cavité externe pompé optiquement. L'émission est accordable autour de la raie D2 du césium à 852,14 nm. La puissance optique est d'environ 10 mW sur chaque polarisation.

Cs atomic clocks based on coherent population trapping require two phase-locked laser lines with output power in the 10-mW range and a frequency difference of about 9 GHz to provide the microwave interrogation. Stabilization of one laser frequency to the reference laser with a phase-locked loop and high-frequency modulation of a diode laser are the...

Using an extremely compact optically-pumped semiconductor vertical external-cavity surface-emitting laser we have demonstrated more than 100mW in single frequency operation at 852.1nm as a solution for Cs atom spectroscopy.

We describe the theoretical modeling of the external-cavity operation of a phase-locked array of diode lasers in two configurations, the self-imaging cavity based on the Talbot effect and the angular-filtering cavity. Complex filtering functions, such as the transmission or reflection of a volume Bragg grating (VBG), may be introduced in the extern...

High power diode laser bars are interesting in many applications such as solid state laser pumping, material processing, laser trapping, laser cooling and second harmonic generation. Often, the free running laser bars emit a broad spectrum of the order of several nanometres which limit their scope in wavelength specific applications and hence, it i...

We demonstrate two different schemes for the spectral narrowing of a 12 emitter 980 nm gain guided tapered diode laser bar. In the first scheme, a reflective grating has been used in a Littman Metcalf configuration and the wavelength of the laser emission could be narrowed down from more than 5.5 nm in the free running mode to 0.04 nm (FWHM) at an...

Diode-pumped semiconductor lasers have already demonstrated high powers in circular diffraction-limited output beams and single-frequency laser emission. Our work is focused on the design of a laser structure suitable for Cesium (Cs) atomic clock experiments that could merge both properties.

We demonstrate the use of a binary diffractive optical element in a very simple setup to convert the multilobed beam from a low fill factor array of coherent laser diodes into a quasi-Gaussian beam. The phase profile of the grating is determined with a phase retrieval algorithm. Experimentally, the conversion efficiency reaches more than 44%. We al...

Phase-locked operation of an array of ten diode lasers is demonstrated in an extended-cavity using the Talbot self-imaging effect. An output power up to 1.7 W has been obtained. The extracavity coherent conversion of the multilobed array supermode into a Gaussian mode is investigated theoretically based on a binary phase grating. The best configura...

Diffraction-limited sources around 976 nm are attractive to build sources around 488 nm, or to pump rare-earth-doped materials. Continuous wave efficient lasers have been obtained with single-mode fibres, in which we demonstrate pulsed laser diode amplification with gains higher than 30 dB. Theoretical studies can predict the amplifier performances...

High-brightness single laser diodes based on the taper design have demonstrated output powers of a few watts with a single transverse mode operation. The use of arrays of such lasers results in a further increase of the laser power, but with the drawback of a loss in the spatial brightness which is reduced as the filling factor of the array. To ove...

We describe passive phase-locking architectures based on external-cavity setups to improve the brightness of diode laser bars. Volume Bragg gratings are used to stabilize the lase line. Numerical modelling and experimental results will be presented.

We report spatial brightness improvement of diode laser arrays in different extended-cavity setups, which take benefit of the narrow spectral bandwidth of volume Bragg gratings to lock the emission spectrum.

High-brightness single laser diodes based on the widespread taper design have demonstrated output powers of a few Watts with a single transverse mode operation. In this work we describe two external cavities intended to improve the spatial brightness of a bar of N=6 index-guided tapered laser diodes emitting around 975 nm. Our external cavity desig...

High-brightness laser diode technology is progressing rapidly in response to competitive and evolving markets. The large volume resonators required for high-power, high-brightness operation makes their beam parameters and brightness sensitive to thermal- and carrier-induced lensing and also to multimode operation. Power and beam quality are no long...

We report on a diode-pumped vertical external-cavity surface-emitting laser emitting around 852 nm for Cesium atomic clocks experiments. We have designed a 7-quantum-well semiconductor structure optimized for low laser threshold. An output power of 330 mW was achieved for 1.1 W of incident pump power. Furthermore a compact setup was built for low-p...

We report on the design and characterization of a single-frequency diode-pumped vertical external-cavity surface-emitting laser emitting at 852 nm for Caesium atomic clock experiments. Up to 120 mW under 1.1 W pumping is achieved.

We present the experimental and theoretical evaluation of the coherent combining of an array of index-guided tapered laser diodes in an external Talbot cavity. A theoretical model taking into account the propagation inside the semiconductor device has been developed to determine the cavity spatial modes. In parallel, experiments have been realized...

We describe both coherent combining and wavelength stabilization of 10 tapered lasers in an external Talbot cavity with a volume Bragg grating. 1.7W at 976 nm in a narrow bandwidth, high coherent beam are obtained.

We present the phase locking of an array of index-guided tapered laser diodes. An external cavity based on the self-imaging Talbot effect has been built. A volume Bragg grating is used as the output coupler to stabilize and narrow the spectrum at 976 nm. A power of 1.7 W is achieved in the in-phase single main lobe mode with a high visibility. We h...

This work reports on an optically-pumped vertical external-cavity surface­emitting laser emitting around 852 nm dedicated to atomic physics experiments with cold Cs atoms. The design of the semiconductor active structure has been optimized to provide a low threshold. A low-power diode-pumped compact prototype has been developed with improved stabil...

RESUME Nous étudions expérimentalement et théoriquement l'amplification d'une diode laser impulsionnelle en cavité étendue dans une fibre monomode dopée par des ions ytterbium. Des gains pouvant atteindre 30 dB ont ainsi été démontrés. MOTS-CLEFS : amplificateur à fibre ; régime impulsionnel ; simulation ; étude expérimentale.

We describe the coherent combining and the wavelength stabilization of 10 tapered lasers in an external Talbot cavity. The use of a volume Bragg grating as feedback element to narrow the spectrum is demonstrated.

We present the diode pumping of a Nd:ASL (Sr1-xLax-yNdyMgxAl12-x O19) crystal for second harmonic generation at 453 nm. We have developed a high-brightness pump source based on a tapered amplifier in an extended cavity with a volume Bragg grating for wavelength stabilization. A pump brightness of 110 MW.cm-2sr-1 is obtained with a linewidth lower t...

We describe the coherent combining and the wavelength stabilization of 10 tapered lasers in an external Talbot cavity. The use of a volume Bragg grating as feedback element to narrow the spectrum is demonstrated

We propose a general method to calculate the dispersion of an arbitrary optical system. It is based on a nonlinear extension of the ABCD matrix model, where each optical element is described as an operator rather than a matrix. The deviation from a reference ray in terms of transverse position, angle, and phase as a function of wavelength is propag...

This work reports on an optically-pumped vertical external-cavity surface- emitting laser (VECSEL) emitting around 852 nm for Cesium atomic clocks experiments. We describe in the following our first results on the design and the characterization of a VECSEL's semiconductor structure suitable for these applications. We optimized the parameters of the...

This work reports on an optically-pumped vertical external-cavity surface­emitting laser (VECSEL) emitting around 852 nm for Cesium atomic clocks experiments. We describe the design and the characterization of a VECSEL semiconductor structure suitable for these applications. The parameters of the structure have been optimized in order to have a low...

We present the diode pumping of a Nd-doped strontium and lanthanum (Nd:ASL) crystal Sr1-xLax-yNdyMgxAl12-xO19 (0.05 ≤ x ≤ 0.5; y = 0.05) for second harmonic generation around 450 nm. In order to fulfill the pumping requirements of this crystal, we have developed a high-brightness pump source based on a tapered amplifier in an extended cavity with a...

The wavelength stabilization of high-brightness extended-cavity lasers at 810-nm by the use of volume Bragg gratings is described. Narrow linewidth (< 20pm), high power (2.5W) and good beam quality (M2<4) operation has been obtained in a robust and simple design. The impact of the beam focusing into the Bragg grating on the external cavity performa...

We describe the strong wavelength-stabilization of high-brightness extended-cavity lasers based on 808-nm and 976-nm tapered amplifiers by use of volume Bragg gratings. Single-frequency operation has been obtained in a robust and simple design.

For the pumping of one Nd:ASL crystal, we have developed a high-brightness external-cavity tapered laser diode stabilized at 798 nm, by use of a volume Bragg grating (VBG) in a simple and compact set-up. Intracavity frequency doubling was performed with a 10-mm-long AR-coated LBO crystal close to the Nd:ASL crystal in a simple plane-concave cavity.

Diode-pumped vertical-external-cavity surface-emitting lasers (VECSELs) have already demonstrated high power, circular diffraction-limited output beams and single-frequency laser emission [1-2]. They appear then to be an interesting way to achieve compact and efficient sources for atomic clocks. We describe in the following our very first results o...

Nonlinear photorefractive materials are well suited to record dynamic volume holograms using the wave mixing of coherent laser beams. The photo-induced index modulation is due to a space charge field which modulates the crystal refractive index. The basic phenomena and beam interactions are reviewed for different types of materials operating in the...

This work reports single-frequency laser oscillation at λ=1003.4nm of a diode-pumped vertical external cavity surface-emitting semiconductor laser for metrological applications. A low thermal resistance of the semiconductor active component is achieved by solid-liquid interdiffusion bonding onto a SiC substrate. The spectro-temporal dynamics of the...