Summary
One of the current aims of nanotechnology is the replacement of ‘slow’ electronic devices with ‘fast’ photonic (light based) ones. Vertical-Cavity Surface-Emitting Lasers (VCSELs) are a promising technology for optical devices as they are compact, inexpensive and power efficient. VCSELs have the second highest production volume of all semiconductor lasers owing to the large number of commercial applications such as Photonic Integrated Circuits (PICs), data transmission, printing and computer mice.
In this context, Researchers from King's College London have invented a novel VCSEL based optical switch. The switch has the ability to operate with plasmonic modes, which are essentially light waves trapped on a metallic surface, and consequently would offer nanoscale confinement of optical energy. This allows the proposed technology to attain the speed and bandwidth of photonic networks, whilst maintaining the reduced dimensions of electronic circuits.
The proposed switch can be implemented on top of current VCSEL designs utilising similar materials already employed in their production.
Technology
Researchers from King's College London have invented a portfolio of optical technologies to manipulate optical signals at the nanoscale including an all optical switch based on Fabry-Perot cavity.
The device relies on the presence of optical resonances to inhibit the coupling of an input signal to optical or plasmonic modes by controlling the output of the source of electromagnetic radiation. This is illustrated in a prototype device in Figure 1. Ultrafast, dynamic control is thus possible via altering the optical properties of the cavity.
A number of options exist for dynamic control of the signal in real-time. For instance, it may be operated all-optically, by pumping the cavity’s mirrors with a secondary pulse of light. Alternatively, the switch may be controlled electrically, via a conductive oxide multilayer. Lastly, a mechanical control of the signal can be achieved by moving the position of one of the cavity’s mirrors.
These control methods have been demonstrated numerically, which offers flexibility in terms of device design, as different switching methods may be tailored to specific applications. For example, the fastest switching rate would be offered by all-optical control, yielding a rate in the Terahertz regime.
Figure 1. Numerical calculation of the ‘On’ and ‘Off’ states (magnetic field), highlighting the change in light coupled to a plasmonic waveguide.
Benefits
- Compact dimensions
- High change in transmission (over 80%)
- Amenable to integration with other on-chip components
- May function as an optical or plasmonic switch
Market Opportunity
The proposed technology relates to Vertical-Cavity Surface-Emitting Lasers (VCSEL), where one of the applications involves Photonic Integrated Circuits (PICs). The global VCSEL market is expected to grow from $501 million in 2013 to $2.1 billion in 2018. A similar annual growth rate is projected for the global PIC market, increasing from $206.5 million in 2013 to $866.4 in 2018 (Source: BCC Research).
This shows that there is already a significant industry in place for VCSEL development and manufacture, which is a considerable advantage for the realisation of the technology and ensures that the financial risks involved are minimised. Furthermore, the proposed switch may be retrofitted to current VCSEL designs utilising similar materials already employed in their production. This ensures that costs remain low when the production volume is scaled up.
The principal advantage of the technology is that it harnesses benefits of VCSELs for signal switching, and may be employed, for example, in Plasmonic PICs. Plasmonics, which offers the confinement of electronics coupled with the speed of photonics, has recently seen significant growth in terms of number of scientific publications, with a fivefold increase in papers published between 2001 and 2011. (Source: Nature Photonics). Moreover, the technology is applicable to the wider VCSEL market, as it has the ability to switch optical signals in addition to plasmonic signals.
An on-chip VCSEL based optical switch has not previously been proposed thus there is no competition in this regard and great potential for transformative applications in integrated photonics.
Commercial Opportunity
Industry partners are sought for commercial development of the technology with a view to taking an option/evaluation licence in the first instance.