Combination of Transverse Mode Selection and Active Longitudinal Mode-Locking of Broad Area Semiconductor Lasers

Experimental results of the combination of transverse mode selection and active mode-locking with anti-reflection-coated broad area lasers (BALs) are presented. The BALs are subject to feedback from a free-space external Fourier-optical 4f-setup with a reflective spatial frequency filter in the Fourier-plane for transverse mode selection. Driving the BALs with a high frequency modulated pump current above threshold active longitudinal mode-locking is achieved. Pulse durations as low as 88 ps are obtained, while the Gaussian-like fundamental or a higher order transverse mode up to mode number 5 is selected on purpose. Pulse duration and shape are nearly independent of the selected transverse mode.

Download Full-text

Fourier-optical transverse mode selection in external-cavity broad-area lasers: experimental and numerical results

IEEE Journal of Quantum Electronics ◽

10.1109/jqe.2002.808147 ◽

2003 ◽

Vol 39 (3) ◽

pp. 448-458 ◽

Cited By ~ 33

Author(s):

S. Wolff ◽

A. Rodionov ◽

V.E. Sherstobitov ◽

H. Fouckhardt

Keyword(s):

Mode Selection ◽

External Cavity ◽

Transverse Mode ◽

Numerical Results ◽

Broad Area ◽

Broad Area Lasers

Download Full-text

Broad area lasers with folded-resonator geometry for integrated transverse mode selection

10.1117/12.873378 ◽

2011 ◽

Author(s):

Dirk Hoffmann ◽

Klaus Huthmacher ◽

Christoph Doering ◽

Henning Fouckhardt

Keyword(s):

Mode Selection ◽

Transverse Mode ◽

Broad Area ◽

Broad Area Lasers

Download Full-text

Fundamental Transverse Mode Selection (TMS#0) of Broad Area Semiconductor Lasers with Integrated Twice-Retracted 4f Set-Up and Film-Waveguide Lens

Advances in OptoElectronics ◽

10.1155/2017/5283850 ◽

2017 ◽

Vol 2017 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Henning Fouckhardt ◽

Ann-Kathrin Kleinschmidt ◽

Johannes Strassner ◽

Christoph Doering

Keyword(s):

Fourier Transform ◽

Semiconductor Lasers ◽

Mode Selection ◽

Transverse Mode ◽

Material System ◽

Round Trip ◽

Broad Area ◽

Trip Length ◽

Set Up ◽

The Fourier Transform

Previously we focused on fundamental transverse mode selection (TMS#0) of broad area semiconductor lasers (BALs) with two-arm folded integrated resonators for Fourier-optical spatial frequency filtering. The resonator had a round-trip length of 4f, where f is the focal length of the Fourier-transform element (FTE), that is, a cylindrical mirror in-between the orthogonal resonator branches. This 4f set-up can be called “retracted once” due to the reflective filter after 2f; that is, the 2f path was used forwards and backwards. Now the branches are retracted once more resulting in a compact 1f long linear resonator (called “retracted twice”) with a round-trip length of 2f. One facet accommodates the filter, while the other houses the FTE, now incorporating a film-waveguide lens. The BAL facet with the filter represents both the Fourier-transform plane (after 2f, i.e., one round-trip) as well as the image plane (after 4f, two round-trips). Thus filtering is performed even after 4f, not just after 2f. Experimental results reveal good fundamental TMS for pump currents up to 20% above threshold and a one-dimensional beam quality parameter M1D2 = 1.47. The BALs are made from AlGaInAsSb, but the concept can equally well be employed for BALs of any material system.

Download Full-text

1D Confocal Broad Area Semiconductor Lasers (Confocal BALs) for Fundamental Transverse Mode Selection (TMS#0)

Advances in OptoElectronics ◽

10.1155/2019/2719808 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Henning Fouckhardt ◽

Ann-Kathrin Kleinschmidt ◽

Johannes Strassner ◽

Christoph Doering

Keyword(s):

Semiconductor Lasers ◽

Focal Length ◽

Mode Selection ◽

Transverse Mode ◽

Round Trip ◽

Broad Area ◽

Absolute Value ◽

Low Pass ◽

Set Up ◽

The Fourier Transform

Previously in this journal we have reported on fundamental transverse mode selection (TMS#0) of broad area semiconductor lasers (BALs) with integrated twice-retracted 4f set-up and film-waveguide lens as the Fourier-transform element. Now we choose and report on a simpler approach for BAL-TMS#0, i.e., the use of a stable confocal longitudinal BAL resonator of length L with a transverse constriction. The absolute value of the radius R of curvature of both mirror-facets convex in one dimension (1D) is R = L = 2f with focal length f. The round trip length 2L = 4f again makes up for a Fourier-optical 4f set-up and the constriction resulting in a resonator-internal beam waist stands for a Fourier-optical low-pass spatial frequency filter. Good TMS#0 is achieved, as long as the constriction is tight enough, but filamentation is not completely suppressed.

Download Full-text