Diamond photonics platform enabled by femtosecond laser writing

Abstract

Diamond is a promising platform for sensing and quantum processing owing to the remarkable properties of the nitrogen-vacancy (NV) impurity. The electrons of the NV center, largely localized at the vacancy site, combine to form a spin triplet, which can be polarized with 532 nm laser light, even at room temperature. The NV’s states are isolated from environmental perturbations making their spin coherence comparable to trapped ions. An important breakthrough would be in connecting, using waveguides, multiple diamond NVs together optically. However, still lacking is an efficient photonic fabrication method for diamond akin to the photolithographic methods that have revolutionized silicon photonics. Here, we report the first demonstration of three dimensional buried optical waveguides in diamond, inscribed by focused femtosecond high repetition rate laser pulses. Within the waveguides, high quality NV properties are observed, making them promising for integrated magnetometer or quantum information systems on a diamond chip.

Inscription of 3D waveguides in diamond using an ultrafast laser

“…It is shown that the presence of the waveguide does not adversely affect the properties of the NV defect making this a promising platform for quantum technologies 40 .…”

Material platforms for integrated quantum photonics

“…NbN-based SNSPDs have been fabricated on polycrystalline diamond surface grown via chemical vapor deposition (CVD) on a silica-onsilicon wafer [109,111] (see Figure 4c). Electro-optomechanical The recently demonstrated femtosecond laser based bulk diamond writing technique [112] may hold potential for flexible waveguide definition. Contrary to III-V QDs, the most promising color centers in diamond emit at wavelengths below 1 μm, which hurdles the prospects of long distance communication.…”

High resolution structural characterisation of laser-induced defect clusters inside diamond

“…27 Similarly, when writing optical waveguides using the stress field generated by modifications in Regime (ii), the propagation losses are significantly lower than those expected from a complete conversion of the irradiated zones to graphite. 23 These observations indicate that the wires' internal structure is more complex than suggested by optical imaging. As illustration, a recent scanning electron microscopy (SEM) study of subsurface DLW structures exposed by mechanical polishing revealed a main fracture containing graphenic carbon and smaller conductive nanocracks propagating from it.…”

“…However, previous Raman studies revealed only the partial formation of sp 2 bonded graphite within the laser irradiated zones. 14,19,23,24 When using such modifications to create wires, the resultant resistivity varies from 0.02 to 2 X cm, [18][19][20]25,26 with values at least an order of magnitude higher than that for polycrystalline graphite. 27 Similarly, when writing optical waveguides using the stress field generated by modifications in Regime (ii), the propagation losses are significantly lower than those expected from a complete conversion of the irradiated zones to graphite.…”

“…[16][17][18] Furthermore, Regime (ii) modifications provide a potential route for all-carbon metamaterials, 19 solar cells, 20 photonic crystals, 21 and waveguides. 22,23 For successful development of DLW in these applications and other diamond based technologies, it is of vital importance to carry out detailed structural analysis of the subsurface laser induced changes to the diamond.…”