Laser source and method of manufacturing such
A laser source for emitting radiation in a given emission spectral band, centered on a given emission angular frequency, the central emission angular frequency is provided. The laser source comprises a laser cavity comprising a gain section having a known frequency dependent Group Delay Dispersion, and a GTI mirror arranged at one end of the gain section, having a known frequency dependent Group Delay Dispersion. The gain section and the GTI mirror are formed into a same laser medium, the laser medium having a known frequency dependent Group Delay Dispersion, and the gain section and the GTI mirror are separated by a gap of predetermined width filled with a dielectric medium thus forming a two parts laser cavity. Further, the GTI GDD at least partly compensates the sum of the Gain GDD and the material GDD in the emission spectral band.
1. A laser source for emitting radiation in a given emission spectral band, centered on a given emission angular frequency, comprising:
a laser cavity comprising a gain section having a known frequency dependent Group Delay Dispersion (GDD), being a Gain GDD, and a Gires Tournois interferometer (GTI) mirror arranged at one end of the gain section, and having a known frequency dependent Group Delay Dispersion, being a GTI GDD, wherein:
the gain section and the GTI mirror are formed into a same laser medium, said laser medium having a known frequency dependent Group Delay Dispersion, being a Material GDD, thus forming a two parts laser cavity;
the gain section and the GTI mirror are separated by a gap of predetermined width (a) filled with a dielectric medium; and
the GTI GDD at least partly compensates a sum of the Gain GDD and the Material GDD in said emission spectral band.
2. The laser source according to claim 1 , wherein the dielectric medium comprises graphene.
3. The laser source according to claim 1 , wherein the dielectric medium is air.
4. The laser source according to claim 1 , wherein the width (a) of the gap is smaller than nc/(nd2w) where nd is the refractive index of the dielectric medium and c is the speed of light in vacuum.
5. The laser source according to claim 1 , wherein the length (L 2 ) of the GTI mirror is determined so that the central emission angular frequency is in a non-resonant frequency sub-band of the GTI GDD.
6. The laser source according to claim 1 , wherein the laser cavity is a mode locked cavity.
7. The laser source according to claim 1 , wherein the gain section is a Quantum Cascade Laser.
8. The laser source according to claim 1 , wherein the laser medium is arranged between two metal layers, a bottom metal layer and a top metal layer, arranged perpendicularly to the growth direction of the laser medium, thus forming a double metal cavity.
9. The laser source according to claim 1 , wherein the central emission angular frequency is comprised between 1 THz and 5 THz.
10. A method for manufacturing a laser source for emitting radiation in a given emission spectral band centered on a given emission angular frequency, comprising the steps of:
depositing a laser medium having a known angular frequency dependent Group Delay Dispersion (GDD), being a Material GDD, on a substrate;
separating the laser medium into two parts, a gain section with a known frequency dependent Group Delay Dispersion, being a Gain GDD, and a GTI mirror with a known frequency dependent Group Delay Dispersionm, being a GTI GDD, thus forming a two parts laser cavity, wherein the GTI GDD compensates a sum of the Gain GDD and the Material GDD in said emission spectral band.
11. The method according to claim 10 , wherein the step of separating the laser medium into two parts comprises:
etching the laser medium to provide a gap of predetermined width (a) filled with a dielectric medium, thus forming said gain section and the GTI mirror.