Project: Highly Coherent Laser for coherent communication and sensing
Attainment of the minimum achievable laser diode linewidth with the least associated level of device complexity and lowest component cost are critical for realizing applications in optical coherent communications and sensing applications. Demands for increased capacity is driving the deployment of higher transmission rates in all parts of the optical network. However, as speeds increase distortion caused by polarization mode dispersion and chromatic dispersion become pronounced, limiting reach. Higher specification components are required at all points in the network to deliver extended reach solutions (eg Long Reach PON). In addition, optical links are rapidly evolving from point-to-point to interconnected architectures. This requires that optical signals have the flexibility to pass multiple optical add-drop multiplexer nodes along the link, introducing further loss and signal distortion. Multi-level formats, such as quadrature phase shift keying provide a promising alternatives to standard binary modulation as they operate at a lower symbol rate for the same total bit rate. Hence, they require lower-speed, but generally higher spec transponder components compared to binary formats. The downside to such solutions is that to achieve the lowest error rates and system margins, there are strong limitations on the source laser spectral linewidth. Optical fiber sensing also requires narrow linewidth laser sources for system sensitivity improvement. Eblana Photonics and CSEM propose this project to develop ultra-narrow linewidth so called 'Discrete Mode' (DM) laser diodes (see Annex file section 6 for intro), that have significantly narrower linewidths than state of the art DFBs. The project will deliver proof of concept demos at lambda = 1550nm. _x000D__x000D_The free-running laser spectral line-width reported for conventional monolithic single mode laser devices is typically high (~100-5000kHz.) and often prevents their use in many applications._x000D_The linewidth behavior for diode lasers in the high power, above threshold limit is governed by the Schalow-Townes (S-T) expression as modified by Henry. The linewidth proportionality to inverse power is well understood, but other dependencies influence the minimum magnitude of the linewidth. These include: (i) the laser a-factor via the laser emission gain peak detuning, (ii) the spontaneous emission coupling into the laser mode and (iii) the cavity length and mirror reflectivities (or cavity finesse). By full optimising of parameters (i) and (iii) Eblana has tailored a specific device structure to achieve a 100kHz emission full width at half maximum (FWHM) linewidth. The difficulty in producing low cost semiconductor lasers with linewidths below 100 kHz results in a need for complex and costly external cavities. Consequently, there is a significant need for the development of a low cost, narrow linewidth laser._x000D_In this project we plan to reduce the free running spectral linewidth of a monolithic laser diode through laser cavity design optimisation utilising a novel technique of amplified spontaneous emission (ASE) reduction through the inclusion of a saturable absorber into the laser diode cavity to reduce the high energy ASE. In a second approach we will demonstrate a platform having a laser monolithically integrated with a phase modulator, where the phase modulator can generate pure PM side-bands for frequency locking and linewidth reduction in the low frequency range. This error signal is then fed back to the laser diode bias current of the laser through a stabilizing loop filter, suppressing the frequency noise within the loop bandwidth of the negative feedback loop. This technique has the potential to be more stable and COtain a small cavity size. This will be performed at 1550nm but the techniques is compatible with different material system and wavelength regions of interest._x000D__x000D_Eblana Photonics is a fabless optoelectronic component supplier concentrating on the supply of single mode laser devices for telecoms and sensing Markets based in Dublin, Ireland. Eblana’s solutions combine cutting edge component performance with applications enabling pricing to offer unrivalled component uniformity. The core offering is a revolution step change in device performance based on Discrete Mode Laser (DML) technology._x000D__x000D_CSEM, Centre Suisse d’ Electronique et de Microtechnique (Swiss Center for Electronics and Microtechnology), founded in 1984, is a private research and development center specializing in microtechnology, nanotechnology, microelectronics, system engineering and communications technologies. It offers its customers and industry Ps custom-made innovative solutions based on its knowledge of the market and technological expertise derived from applied research. Having founded several start-ups, it contributes to developing Switzerland as an industrial location. To date, a total of 29 such enterprises, with more than 500 employees, have been launched by CSEM.
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Acronym
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HICOLA
(Reference Number: 8598)
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Duration
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01/12/2013 - 31/08/2016
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Project Topic
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Using advanced semiconductor laser fabrication technology, the project is targeting to demonstrate feasibility of the novel narrow linewidth semiconductor laser product incorporating simple and cost effective means for natural linewidth reduction and active wavelength stabilization.
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Network
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Eurostars
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Call
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Eurostars Cut-Off 10
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Project partner
