An optically-transparent device configured to form a field intensity distribution in a near zone of the device from an electromagnetic wave incident on a first surface of the device that has a second surface opposite the first surface, wherein the device is embedded in a first dielectric material having a first refractive index n 1, the device comprising: a main part made of a second dielectric material having a second refractive index n 2, wherein the second refractive index n 2 is higher than the first refractive index n 1; and an insert made of a third dielectric material having a third refractive index n 3 that is lower than the second refractive index n 2, the third refractive index n 3 being different from the first refractive index n 1, and the insert is within the main part, wherein a width of the main part and a width of the insert are configured such that W 1 -W 2 ≥λ/2 and 2Wi:510A, with W 1 corresponding to a half-width of the main part, W 2 corresponding to a half-width of the insert, and λ corresponding to a wavelength of the incident electromagnetic wave in the main part, and wherein a first nanojet beam is generated by a first edge of the main part, wherein the first edge of the main part is adjacent to the first dielectric material; wherein a second nanojet beam is generated by a first edge of the insert, wherein the first edge of the insert is adjacent to the second dielectric material of the main part; and wherein the first nanojet beam and the second nanojet beam recombine to form a first nanojet hot spot in a space of the host medium extending away from a first section of the second surface; and wherein a third nanojet beam is generated by a second edge of the main part, wherein the second edge of the main part is adjacent to the first dielectric material; wherein a fourth nanojet beam is generated by a second edge of the insert, wherein the second edge of the insert is adjacent to the second dielectric material of the main part; and wherein the third nanojet beam and the fourth nanojet beam recombine to form a second nanojet hot spot in a space of the host medium extending away from a second section of the second surface. a main part made of a second dielectric material having a second refractive index n 2, wherein the second refractive index n 2 is higher than the first refractive index n 1; and an insert made of a third dielectric material having a third refractive index n 3 that is lower than the second refractive index n 2, the third refractive index n 3 being different from the first refractive index n 1, and the insert is within the main part, wherein a width of the main part and a width of the insert are configured such that W 1 -W 2 ≥λ/2 and 2Wi:510A, with W 1 corresponding to a half-width of the main part, W 2 corresponding to a half-width of the insert, and λ corresponding to a wavelength of the incident electromagnetic wave in the main part, and wherein a first nanojet beam is generated by a first edge of the main part, wherein the first edge of the main part is adjacent to the first dielectric material; wherein a second nanojet beam is generated by a first edge of the insert, wherein the first edge of the insert is adjacent to the second dielectric material of the main part; and wherein the first nanojet beam and the second nanojet beam recombine to form a first nanojet hot spot in a space of the host medium extending away from a first section of the second surface; and wherein a third nanojet beam is generated by a second edge of the main part, wherein the second edge of the main part is adjacent to the first dielectric material; wherein a fourth nanojet beam is generated by a second edge of the insert, wherein the second edge of the insert is adjacent to the second dielectric material of the main part; and wherein the third nanojet beam and the fourth nanojet beam recombine to form a second nanojet hot spot in a space of the host medium extending away from a second section of the second surface.