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Spectral characteristics of nonlinear pulse compression in semiconductor Bragg gratings

Spectral characteristics of nonlinear pulse compression in semiconductor Bragg gratings
Spectral characteristics of nonlinear pulse compression in semiconductor Bragg gratings
We present here an experimental investigation of nonlinear pulse compression in AlGaAs waveguide gratings. In contrast to previous experiments[1] we have been able to characterise the compressed pulses both spectrally and temporally. This is due to the high nonlinearity of AlGaA4s which allows high repetition pulse sources to be used. The gratings used were fabricated using a single step electron beam technique described earlier[2]. The gratings were 8mm long and were approximately 99% reflecting. A number of identical gratings were fabricated on each AlGaAs wafer to allow comparison between gratings. Incident upon the gratings was a 100kHz 415ps transformed limited pulse source at 1536nm. The peak power launched was 600W. We tuned the pulse source to lie in the centre of the bandgap and our results are shown in Fig. 1. As can be seen the pulse compresses from 415ps to 80ps (detector limited) while at the same time the spectrum broadens considerable. Importantly the spectrum is now asymmetric with the majority of the energy lying on the short wavelength side of the grating. This indicated that in the nonlinear regime a significant fraction of the energy has been switched out of the grating's bandgap. In other experiments we measured a 10dB increased in the transmissivity[2].
We have modeled these experiments using the standard nonlinear coupled mode equations and have obtained qualitative agreement with the experiments. We expect to obtain better agreement using a more accurate model. In conclusion we have observed for the first time spectral features associated with the formation of solitons in nonlinear Bragg gratings.
Figure 1: Output temporal and spectral profiles for an input 415ps transformed limited Gaussian pulse
Broderick, N.G.R.
4cfa2c7c-097a-48d6-b221-4e92ad1c6aea
Millar, P.
32f53b19-1dde-4d6a-9803-fe0c66756ba9
Richardson, D.J.
ebfe1ff9-d0c2-4e52-b7ae-c1b13bccdef3
Aitchison, J.S.
32efde36-6ee4-4cc4-9db8-3297e54d7184
De La Rue, R.
4adf326e-2926-453a-8c24-8d2d9c698667
Krauss, T.
9edaab28-aa64-4010-bfd2-619f281dbf0a
Broderick, N.G.R.
4cfa2c7c-097a-48d6-b221-4e92ad1c6aea
Millar, P.
32f53b19-1dde-4d6a-9803-fe0c66756ba9
Richardson, D.J.
ebfe1ff9-d0c2-4e52-b7ae-c1b13bccdef3
Aitchison, J.S.
32efde36-6ee4-4cc4-9db8-3297e54d7184
De La Rue, R.
4adf326e-2926-453a-8c24-8d2d9c698667
Krauss, T.
9edaab28-aa64-4010-bfd2-619f281dbf0a

Broderick, N.G.R., Millar, P., Richardson, D.J., Aitchison, J.S., De La Rue, R. and Krauss, T. (1999) Spectral characteristics of nonlinear pulse compression in semiconductor Bragg gratings. 14th National Quantum Electronics Conference (QE14), United Kingdom. 06 - 09 Sep 1999.

Record type: Conference or Workshop Item (Paper)

Abstract

We present here an experimental investigation of nonlinear pulse compression in AlGaAs waveguide gratings. In contrast to previous experiments[1] we have been able to characterise the compressed pulses both spectrally and temporally. This is due to the high nonlinearity of AlGaA4s which allows high repetition pulse sources to be used. The gratings used were fabricated using a single step electron beam technique described earlier[2]. The gratings were 8mm long and were approximately 99% reflecting. A number of identical gratings were fabricated on each AlGaAs wafer to allow comparison between gratings. Incident upon the gratings was a 100kHz 415ps transformed limited pulse source at 1536nm. The peak power launched was 600W. We tuned the pulse source to lie in the centre of the bandgap and our results are shown in Fig. 1. As can be seen the pulse compresses from 415ps to 80ps (detector limited) while at the same time the spectrum broadens considerable. Importantly the spectrum is now asymmetric with the majority of the energy lying on the short wavelength side of the grating. This indicated that in the nonlinear regime a significant fraction of the energy has been switched out of the grating's bandgap. In other experiments we measured a 10dB increased in the transmissivity[2].
We have modeled these experiments using the standard nonlinear coupled mode equations and have obtained qualitative agreement with the experiments. We expect to obtain better agreement using a more accurate model. In conclusion we have observed for the first time spectral features associated with the formation of solitons in nonlinear Bragg gratings.
Figure 1: Output temporal and spectral profiles for an input 415ps transformed limited Gaussian pulse

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More information

e-pub ahead of print date: 1999
Venue - Dates: 14th National Quantum Electronics Conference (QE14), United Kingdom, 1999-09-06 - 1999-09-09

Identifiers

Local EPrints ID: 76522
URI: https://eprints.soton.ac.uk/id/eprint/76522
PURE UUID: ce00e93f-03af-4e49-9bbf-dfd38a210981
ORCID for D.J. Richardson: ORCID iD orcid.org/0000-0002-7751-1058

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Date deposited: 11 Mar 2010
Last modified: 06 Mar 2019 01:37

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