Alantys Technology R & D by simultaneously implement our skills, partnerships and funding.
Our particular project is built around two main axes: one is, firstly, to establish a strong partnership with ENS and secondly to develop a patent under a public-private partnership.

The researcher Jerome Tignon, Professor UPMC, Pierre Aigrain Laboratory of the Ecole Normale Supérieure has established a development plan for our joint R & D in our partnership as follows:

 

We recall that in preliminary our R & D aims to establish microscopic prototype boxes quantum cryptography. It is easy to realize such devices in a box of one cubic meter, there are very significant technological obstacles when you want to miniaturize the technology to make it available in a box of a cubic centimeter, for example, place in a small electronic device like a mobile phone for example.
Under the partnership, we start from the valuation of a pre-existing patent we could industrialize together, once developed prototypes (experimental research, applied research)We have Grassé terms that we felt were essential in the proposed R & D.

“Micro – optical parametric oscillator coupled cavity”
This text is in the form of pre – project to allow a first discussion on funding opportunities. I would be obliged if you would inform me if you need clarification or deepening.
Summary

Quantum cryptography requires a light source which can either be a source of coherent states, a single photon source, or a source of twin photons. The generation of twin photons (or entangled), which is the most promising in terms of distance communication channel, is usually obtained in a non-crystal – excited by a linear laser. Nevertheless, the generation mechanism is very efficient, which greatly limits the flow.The most effective sources based on the use of macroscopic systems whose size and cost severely limit any use outside of a laboratory. This project aims at the realization of micro – integrated photon sources twins . The generation of twin photons is obtained by parametric interaction between the electronic excitations of the active medium (set of quantum wells) of a structure coupled microcavities has similarities with two – or three – VCSEL. The physical principle in – underlying is similar to that used in conventional parametric sources using large systems. The originality of the proposed source is to provide a solution to obtain a source of micrometer size as an optoelectronic component. The grown nanostructures are compact, can be electrically injected and are compatible with a coupling of the photons generated within the optical fiber for transmission of information. General physical and technical principles are described in the patent document
“Micro – optical parametric oscillator coupled cavity” held by the CNRS and the principal inventor J. Tignon.
State of work in progress

Since the drafting of the patent, a number of advances were obtained after manufacture (molecular beam epitaxy jets LPN – CNRS) and study:

1) In early studies, the photons (or beams) twins were both emitted perpendicularly to the surface of the nanostructure, with slightly different wavelengths. This resulted in two major drawbacks: (i) it was not possible to easily separate the two twin beams, (ii) the complementary beam emitted at shorter wavelength, was less intense than the signal beam. The new geometry called
“Degenerate wavelength” now used to generate beams perfectly balanced in intensity and spatially separated by an angle of a few degrees. This configuration requires more than two coupled cavities instead of three initial and handling of twin beams thus generated is greatly simplified.

DESIGN INITIAL TRIPLE CAVITY:
 width=

Figure 1: Left: Schematic of the triple pump cavity. Centre: FIG dispersing cavities non – coupled (left) and coupled cavities (right). The arrows indicate the parametric mechanism creating the twin beams and complementary signal (idler). Right: Measured far-field emission. See article: C. Diederichs et al, Nature 440, 904 (2006).. “Pump” describes the external pump laser which is intended to be replaced by an electrical injection and this is achieved in VCSELs.

 width=


NEW SCHEMA DOUBLE CAVITY:
Figure 2: Left: schema pumping and generation of twin beams. Centre: FIG dispersion and the principle of generation degenerate parametric wavelength. Right: measuring the intensity of the signal and complementary threshold showing the optical parametric oscillation and a balanced signal and a complementary intensity.

2) The working temperature was increased to room temperature while early studies were limited to cryogenic temperatures (liquid helium) with the nanostructure placed in a cryostat.
It should be noted, however, that studies at room temperature must be reproduced and deepened.

 width=


Figure 3: operation of the nanostructure at room temperature (300 K).
3) measures “quantum noise” as well as measures of correlation (g (2)) were performed on the twin photons generated, which allowed us to demonstrate the parametric nature of photons generated in the nanostructure. This work is still ongoing in the laboratory.

 

Proposals for the project

 

studies so far are relatively basic. It would be desirable to provide engineering support now to drive the project to completion to achieve a fully operational optoelectronic component. We suggest contacting an industrial component manufacturer VCSEL in order to produce a set of complementary nanostructures.

 

This effort should be to:
i) the manufacture of structures for improving performance at room temperature
(Ii) the manufacture of structures for operation at 1.55 mm (wavelength of Telecom)
(Iii) develop electric injection structures
(Iv) to test a new scheme microcavity operating in the non – linearity Chi (2) and not on the Chi (3) as is the case in the current structures. The manufacturing cost of such samples from an industrial remains to encrypt and I propose that this be the subject of a discussion between us before we go any further.

As has been discussed at our first meeting, it would be very beneficial if funding allows, hire engineers (and / or PhD) dedicated to the project for the whole “more applied” part of the project.
For the upstream part, we propose the purchase of several facilities for the continuation of ongoing studies within the LPA at ENS (including studies at 1.55 mm).

Manufacturing new structures
Remaining Cost to quantify based on our discussions.
1) Operation at room temperature.

The development of a component operating at ambient temperature requires the manufacture of a set of several structures specially

designed by us, containing more quantum wells, and thicker than the current structures Bragg mirrors. These structures must be fabricated by molecular beam epitaxy, and by (or equivalent technique), in the GaAs / AlGaAs compounds. At this stage of development and if funding permits, it would be advisable to contact an industrial company specialized in the manufacturing of VCSELs rather than continue to work with our usual lab partner whose delays are too long and do not test a sufficiently large number of structures. VCSELs structures are technologically very similar structures that concern us here, we know that the technology exists to obtain adequate manufacturing project.
At first, the structures in question can be optically pumped as we are currently in the laboratory (with a laser Ti: Sa). In a second step, it would be advisable to request the production of an integrated electric injection as is commonly done in the industry for VCSELs (with the same company). Get it from an industrial greatly reduce the time of the project. In fact, this activity is basically an engineering activity well understood by industry but beyond the scope and interest of a laboratory as LPA.
Structures thus produced can be tested for optical measurements LPA ENS.

2) Micro — OPO at 1.55 microns

The most common VCSELs are made to the range 750 – 950nm made of GaAs / AlGaAs material. Operating at 1.55 microns requires the use of materials phosphide (InP InAlGaAsP example). For the manufacture of such structures, which are much better suited for propagation over long distances in optical fibers, we propose to contact a company that knows manufacture VCSELs in both material systems. Tests on structures emitting at these wavelengths require the purchase of additional equipment for the LPA (see below).

3) Chi Cavity (2) to 1.55 microns
Operation at 1.55 microns can a priori be obtained by a physical principle, slightly different from the one studied so far, but still using materials based on GaAs (unpublished work). We also offer to manufacture such structures whose growth is a priori easier than for materials on InP.

Equipment for laboratory

Here is a list of equipment necessary a priori. During our discussion CNRS,
Mr. MAUCHIEN (binding partner between Alantys and CNRS) had discussed the idea that part of the work could be carried out of the LPA, for example, dedicated to developing a more technical aspects. If this is the case, it will add to the equipment above – below a further list to equip a new set – up experimental (optical table, optical and mechanical components, basic electronics, etc..).

1) Continuous singlemode laser (102 k – Euro) and pump laser (88 k – Euro) A continuous single-mode laser would be desirable to study the actual Statistical twin photons generated. At present, the LPA continuous mode uses a laser is normally to generate short pulses. This results in an uncertainty on some measures and numerous delays.

2) 1.55 mm tunable laser (47 k – Euro)
The study of structures emitting at 1.55 mm require as a first step to be able to excite using an optical pump. This requires a laser
Frequency tunable 1.55 mm so as to precisely adjust the wavelength of the pump. In a second step, the structures are electrically injected.

3) cooled InGaAs CCD (80 k – Euro)

Optical characterization and study of structures emitting at 1.55 mm require the acquisition of a cooled InGaAs CCD camera (to reduce the measurement noise).

4) Sensors for correlations 1.55 mm (42 k – Euro) and associated card (22 k – Euro)
This equipment would study the statistics of photons emitted at 1.55 mm to demonstrate that their properties have the performance required for applications in quantum optics.

A first estimate for all facilities above – is 381 k – euros (excluding the manufacture of structures). If possible, it would be desirable to add a small budget for equipment opto – mechanical (mirrors, lenses, linear stages etc).

Team description of LPA
The “optical” team at Laboratoire Pierre Aigrain, ENS specializes in coherent optical and non – linear for the study of semiconductor nanostructures (microcavities, quantum dots, carbon nanotubes) for the confinement of electronic excitations or photons . The experimental facilities include a particular set of femtosecond lasers / picosecond Ti: Sa regenerative amplifier, OPA, a set of spectrometers and cryostats.

Biography of Jérôme Tignon
Tignon Jerome was born in 1969 in France. He studied at the Ecole Normale Supérieure (MIP) and the University Pierre et Marie Curie (Paris 6). After a “quantum physics” DEA, he completed his thesis LPMC ENS (ed. C. Delalande) thesis in which he studied the optical properties of semiconductor nanostructures. In 1996, he joined the group of DS Chemla Lawrence Berkeley National Lab (Berkeley, California) for a post – doc 2 years, where he conducted research on ultra spectroscopy – fast (fs) of III – V (4-wave mixing interferometry). In 1998, he joined the LPA ENS to develop “coherent optical and non – linear” activity. His main contributions of the time concern in particular the dynamics of

microcavity polaritons (4-wave mixing, pump – probe). He filed a patent on the micro – vertical cavity OPO (Nature 2006). As of 2005, Jerome Tignon has developed a new independent team within the LPA for THz spectroscopy ultra – fast. He hosts from a team of 3 permanent (with S. Dhillon and J. Mangeney, both CR – CNRS). The topics studied mainly the THz quantum cascade lasers (study of gain, injection modelocking of QCLs). Among the most recent topics include the study of coupling ultra – strong and inter polaritons – subbands, the study of spin excitations in diluted semimagnetic semiconductors or the study of graphene. Jérôme Tignon was appointed professor in 2006, he has coordinated and participated in numerous national and international networks and contracts (EU and USA). He is the author of over 90 publications (including PRL, Nature, Nature Photonics, APL, IEEE etc..), Holds one patent and has given more than 25 invited presentations. It was or is a director of 10 theses since HDR. It was “flesh” for the organization of an international conference in Paris (300 participants) was director of an international school. He was a member of the evaluation committee of the ANR (SIMI 10).