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Diode-side-pumped channel waveguide laser

Diode-side-pumped channel waveguide laser
Diode-side-pumped channel waveguide laser
Fundamental-mode channel waveguide lasers, while offering high pump and signal intensities and excellent pump-signal mode overlap, usually require a fundamental-mode pump source, thus limiting the diode pump power that can be launched into the waveguide to typically less than 1 W, thereby also setting limitations on the achievable output power. Here we demonstrate laser emission from a highly Yb3+-doped, tapered channel waveguide in KGdxLu1-x(WO4)2 by diode side pumping with a high-power, multi-mode diode bar via a passive planar waveguide, offering the potential for significantly increased output powers.
We have chosen KGdxLu1-x(WO4)2:Yb3+ for its large pump-absorption cross-section at 981 nm. Multi-layer growth of lattice-matched layers [1] with various compositions is applied to design the refractive-index contrast and active properties of the laser device (Fig. 1). A 1.7 to 0.6-µm-high, horizontally tapered waveguide structure is etched into the 5mm-long KGd0.447Lu0.078Yb0.475(WO4)2 active layer [2] to allow for efficient pump absorption under side pumping in its 50-µm-wide waveguide section and simultaneously ensure single-mode laser emission via its 5-µm-narrow waveguide section. The pump power is delivered from the side through a 5 to 2.5-µm-high passive KGd0.114Lu0.116Y0.77(WO4)2 slab waveguide overgrown and surrounding the active tapered waveguide.
The multi-mode, 30-W diode bar is mounted on a water-cooled chuck without active temperature control, resulting in a pump wavelength around 980 nm (Fig. 2a). The pump beam is modulated by a chopper with 2.9% duty cycle to reduce the thermal load. Mirrors are butt-coupled to the waveguide endfacets by use of a fluorinated oil, with reflection at 1040 nm of 99.8% and 90% at the wide and narrow active-waveguide end, respectively. No additional measures are taken to cool the sample. With this first, non-optimized device a maximum output power of 10 mW (Fig. 2a) when pumped with a cold diode (operating close to the absorption peak) and laser wavelength of 1038nm (Fig. 2b) are detected. Relaxation oscillations and the mode profile of laser emission with satellite spots, indicating a non-ideal taper structure, are recorded (Fig. 2c).
Geskus, D.
2abd96ed-8ced-47ce-b2c2-28e008edea65
Grivas, C.
7f564818-0ac0-4127-82a7-22e87ac35f1a
Aravazhi, S.
466dd0ea-aae1-4d35-b212-e598e0228cd1
Griebner, U.
99206079-3e6b-42da-836f-7dd3b154e303
García Blanco, S.M.
55b80f55-cdaa-4d13-818f-c6aec3103d68
Pollnau, M.
1094856b-791a-4050-98d9-c07777d5f0f5
Geskus, D.
2abd96ed-8ced-47ce-b2c2-28e008edea65
Grivas, C.
7f564818-0ac0-4127-82a7-22e87ac35f1a
Aravazhi, S.
466dd0ea-aae1-4d35-b212-e598e0228cd1
Griebner, U.
99206079-3e6b-42da-836f-7dd3b154e303
García Blanco, S.M.
55b80f55-cdaa-4d13-818f-c6aec3103d68
Pollnau, M.
1094856b-791a-4050-98d9-c07777d5f0f5

Geskus, D., Grivas, C., Aravazhi, S., Griebner, U., García Blanco, S.M. and Pollnau, M. (2012) Diode-side-pumped channel waveguide laser. 5th EPS-QEOD Europhoton '12, Stockholm, Sweden. 26 - 31 Aug 2012.

Record type: Conference or Workshop Item (Paper)

Abstract

Fundamental-mode channel waveguide lasers, while offering high pump and signal intensities and excellent pump-signal mode overlap, usually require a fundamental-mode pump source, thus limiting the diode pump power that can be launched into the waveguide to typically less than 1 W, thereby also setting limitations on the achievable output power. Here we demonstrate laser emission from a highly Yb3+-doped, tapered channel waveguide in KGdxLu1-x(WO4)2 by diode side pumping with a high-power, multi-mode diode bar via a passive planar waveguide, offering the potential for significantly increased output powers.
We have chosen KGdxLu1-x(WO4)2:Yb3+ for its large pump-absorption cross-section at 981 nm. Multi-layer growth of lattice-matched layers [1] with various compositions is applied to design the refractive-index contrast and active properties of the laser device (Fig. 1). A 1.7 to 0.6-µm-high, horizontally tapered waveguide structure is etched into the 5mm-long KGd0.447Lu0.078Yb0.475(WO4)2 active layer [2] to allow for efficient pump absorption under side pumping in its 50-µm-wide waveguide section and simultaneously ensure single-mode laser emission via its 5-µm-narrow waveguide section. The pump power is delivered from the side through a 5 to 2.5-µm-high passive KGd0.114Lu0.116Y0.77(WO4)2 slab waveguide overgrown and surrounding the active tapered waveguide.
The multi-mode, 30-W diode bar is mounted on a water-cooled chuck without active temperature control, resulting in a pump wavelength around 980 nm (Fig. 2a). The pump beam is modulated by a chopper with 2.9% duty cycle to reduce the thermal load. Mirrors are butt-coupled to the waveguide endfacets by use of a fluorinated oil, with reflection at 1040 nm of 99.8% and 90% at the wide and narrow active-waveguide end, respectively. No additional measures are taken to cool the sample. With this first, non-optimized device a maximum output power of 10 mW (Fig. 2a) when pumped with a cold diode (operating close to the absorption peak) and laser wavelength of 1038nm (Fig. 2b) are detected. Relaxation oscillations and the mode profile of laser emission with satellite spots, indicating a non-ideal taper structure, are recorded (Fig. 2c).

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More information

e-pub ahead of print date: 2012
Additional Information: WeP.5
Venue - Dates: 5th EPS-QEOD Europhoton '12, Stockholm, Sweden, 2012-08-26 - 2012-08-31
Organisations: Optoelectronics Research Centre

Identifiers

Local EPrints ID: 362997
URI: http://eprints.soton.ac.uk/id/eprint/362997
PURE UUID: 363e114e-4a3e-4da8-af67-89b19bca7747

Catalogue record

Date deposited: 19 Mar 2014 12:37
Last modified: 29 Jul 2019 16:31

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