Polymer long-period raised rib waveguide gratings using nano-imprint lithography

Abstract

This letter presents the fabrication and demonstration of a long-period raised rib waveguide grating using nano-imprint lithography. The device consists of a lower UV15 cladding, where relief-gratings are implemented, and an NOA73 raised rib core waveguide. Spectral transmission reveals a resonance at 1585 nm with about 10-dB rejection and 12-nm linewidth.

Widely tunable long-period waveguide grating filters

“…More seriously, because the grating is made before the cladding is formed, this technique demands a precise control of the cladding characteristics, which can be difficult for some polymer materials. A nano-imprint lithographic technique has also been demonstrated for the fabrication of a LPWG in a rib waveguide [22]. Compared with photolithography and RIE, the imprinting technique is simpler and less costly, and can be further developed for mass production.…”

“…LPWGs have been demonstrated experimentally with different materials, including glass [10,12,17], polymer [9][10][11][12][13][14][15][18][19][20][21][22][23][24][25][26][27][28], and semiconductor [29], and in different waveguide structures, including slab waveguides [9,10,12], ridge waveguides [13,15], rib waveguides [22], and channel waveguides [11,14,[18][19][20][21][23][24][25][26][27][28][29]. The large thermo-optic coefficient of polymer (about 25 times larger than that of glass) allows the rejection bands of many of the polymer LPWGs to be tuned thermally over a wide range of wavelengths [9][10][11][12][13][14][15]…”

“…Permanent gratings have been fabricated by the conventional photolithographic and etching technique [9][10][11][12]14,18,21,25,28,29], the nano-imprinting technique [22], and the UV/laser-writing technique [13,15,24]. Gratings with a tunable contrast based on the thermo-optic effect of polymer have been demonstrated by depositing suitable electrode gratings on polymer waveguides [19,20,23,26,27].…”

Hybrid silica/polymer long period gratings for wavelength filtering and power distribution

“…Planar LPGs have been researched in detail and many literature contributions cover theoretical calculation and structure design [16,17] as well as grating implementation in various materials, ranging from glass to polymers [18][19][20][21][22][23]. LPGs have been demonstrated in benzocyclobutene ridge waveguides with the effective refractive index change induced by KrF excimer laser irradiation [18], in ion-exchanged BK7 glass slab waveguides [19], and other polymer waveguides by reactive ion etching [20] or by soft lithography [21]. Thermally induced refractive index modulation gratings have also been reported to exhibit strong wavelength rejection bands in polymer ridge waveguides [22,23].…”

Polymeric waveguide Bragg grating filter using soft lithography

“…Chemically inertness and the elastic behavior of the PDMS (poly-dimethylsiloxane) make it the main material for soft lithography. Previously, this technique has been applied to fabricate a number of optical devices such as optical couplers, polymeric lasers [4], resonators [5] and modulators [6] and long period gratings [7].…”