Photonic Design Automation (PDA) tools have been commercially available for over 10 years, and allow devices, circuits systems and network concepts to be developed and optimized on computers before prototypes are built, allowing more design options to be tested at a lower cost [1], [2]. PDA is now widely used in industry and many commercial systems and devices were developed using PDA tools. PDA is also widely used in education, with freely available cut-down software, and free software that allows simulations to be 'played' but not created [3].

The usual output of PDA software is visual [2]: spectra, optical and electrical waveforms and spectra, Poincare spheres, x-y plots, tabulated results such as channel-by-channel performance measures. This work presents an alternative output format, that is, audio. Because the ear is very sensitive to pitch variations with time, audio outputs are good indications of the spectral content of signals, such as spectral purity and stability. Granted, an audio output is difficult to compare quantitatively; however, it may still be useful in the design process, as it can be used as a basis of discussion between engineers, managers and customers, as it can call on the rich language of sound and music. It is also educational - laser chirp is easily remembered once you have heard it, and four-wave mixing becomes 'real'.

Some interesting examples of how photonic devices and systems 'sound' are:

• Multimode Fabry-Perot Laser Multimode Laser Left + Right Facets.wav MP3

• Self-Pulsating DFB Laser Self Pulsating DFB Left + Right Facets.wav MP3

• Directly-Modulated Laser Models DFB-GC + SMRE Laser Models.wav MP3

• Electro-Absorption Modulator and DFB Laser DFB EAM Left + Right Outputs.wav MP3

• DFB Laser with Delayed Feedback Laser with Feedback Facet + Fiber.wav MP3

• Tunable Distributed-Bragg Reflector/Fabry-Perot Laser DBR FP Tunable Laser Left + Right Facets.wav MP3

• Fiber Nonlinearity: Four Wave Mixing 4 channel FWM + Sideband.wav MP3

• Advanced Modulation Scheme CSRZ DPSK + Manchester.wav MP3

• Polarization Modulation Polarization Modulation LinHorz + LinVert.wav MP3

The .wav files can be edited with programs such as Audacity [4], which can also create spectrograms.

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References

1.  Andre Richter, Igor Koltchanov and Arthur Lowery "Photonic design automation of optical communication systems", Asia Pacific Optical Communications Conference, 7-11th November, Beijing, China, 2004

2. A. J. Lowery "Photonic Simulation Tools", in Optical Fiber Telecommunications IV-B: Systems and Impairments,  Ivan Kaminow and Tingye Li eds. (Academic Press, New Jersey, 2002)

3. A. J. Lowery "Free take-home virtual laboratories using professional simulation software", Presentation EMD2, Education and Training in Photonics (ETOP'03), Oct 6-8, 2003, Tucson, Arizona (organized by the Optical Society of America, available on CD-ROM)

4. "Audacity, the free cross-platform sound editor" from http://audacity.sourceforge.net/

Arthur is currently seeking PhD students to help create new global industries from high-tech research. He can be contacted at Arthur.lowery@eng.monash.edu.au