Multi-mode interfered waveguide-type lithium niobate-based optical power distributor
Technical field
The present invention relates to a kind of waveguide type optical power distributor.
Background technology
Utilization is a kind of new device from multiple-mode interfence (MMI) the type device of mirror effect, and its Design Theory and manufacturing process are relatively easy, has device size compactness, light good uniformity and extensively being paid attention to along separate routes simultaneously.The multi-mode interfered waveguide-type optical power distributor is to be made of single mode input waveguide, multiple-mode optical interference district and single mode output waveguide.This multi-mode interfered waveguide-type optical power distributor is based on the step-refraction index distribution waveguide, because traditional all is at based on the step-refraction index distribution waveguide from the mirror effect analysis, yet in the application of integrated optics, it is that graded index distributes that most waveguide is arranged, as the lithium niobate waveguide (LiNbO that obtains with proton exchange
3) the present still blank of research.
Summary of the invention
The purpose of this invention is to provide a kind of on lithium niobate substrate 1 * N multi-mode interfered waveguide-type optical power distributor of graded index distribution waveguide.
The objective of the invention is to realize by following measure: comprising 1 * N multi-mode interfrence optical waveguide, is the multiple-mode optical interference district that the graded index distribution is set on lithium niobate substrate, single mode input waveguide and N the single mode output waveguide that reaches two ends, multiple-mode optical interference district.
When waveguide is set, at first determine the waveguide parameter of index distribution function, operation wavelength and the single mode operation state of graded index distribution waveguide, choose the multiple-mode optical interference sector width then, one end center is aided with the single mode input waveguide in the multiple-mode optical interference district again, evenly arrange N single mode output waveguide at the multiple-mode optical interference district other end, the length L in the corresponding multiple-mode optical interference district when at first utilizing three-dimensional full vector finite difference beam Propagation method to seek each single mode output waveguide luminous power to be in maximal value
i(i=1,2,3 ... N), then successively with L
iBe the multiple-mode interfence section length, change the center of i single mode output waveguide, the center of i single mode output waveguide when utilizing three-dimensional full vector finite difference beam Propagation method to seek i single mode output waveguide maximum Output optical power once more.
The present invention is owing to adopted the graded index distribution waveguide; can be very high and have 1 * N multi-mode interfered waveguide-type optical power distributor of producing function admirable on the lithium niobate substrate of fine optical characteristics in the commercialization degree with simple technology manufacturing process; further commercialization; low input, high production form large-scale production.And can further develop M * N multi-mode interfered waveguide-type photo-coupler.
Description of drawings
Fig. 1 is the present invention a kind of 1 * 8 a waveguiding structure synoptic diagram.
Embodiment
With reference to Fig. 1, specific design parameter of the present invention depends on lithium niobate substrate and concrete proton exchange technological process.From practical standpoint, selected proton exchange lithium niobate waveguide will have and the index distribution and the single mode waveguide size of communicating by letter and mating as far as possible with standard single-mode fiber.Simulate on this basis and optimize analysis, choose other parameter.Parameter does not have absolute value.Cutting X biography lithium niobate substrate with Z is substrate, the particle exchanging technology of annealing, selected waveguide parameter (N=8 is an example) is: operation wavelength is 1.55 μ m, the width of single mode input waveguide 1 and each single mode output waveguide 3 is 6 μ m, length is 3000 μ m, this parameter has certain arbitrariness, for termination is quoted, N=8, i.e. 1 * 8 multi-mode interfered waveguide-type optical power distributor, the width in multiple-mode optical interference district 2 is 128 μ m, on this basis, (this moment, 1 * 8 multi-mode interfered waveguide-type optical power distributor had big Output optical power to utilize three-dimensional full vector finite difference beam Propagation method to calculate the optimum length in corresponding multiple-mode optical interference district 2, and power uniformity coefficient preferably arranged) be 2930 μ m, when the center of single mode input waveguide 1 was 0, the center of 8 single mode output waveguides 3 was respectively-55.6 μ m from the bottom to top,-39.8 μ m,-23.8 μ m,-7.9 μ m, 7.9 μ m, 23.8 μ m, 39.8 μ m, 55.6 μ m.
Manufacture craft: 1. Z cuts X biography lithium niobate substrate and makes desired standard substrate sheet through cutting, corase grind, finishing polish; 2. utilize vacuum evaporation technique on lithium niobate substrate, to steam the thick aluminium film of 1 μ m; 3. after the aluminium film on the substrate being carried out photoetching, with 70 ℃ phosphoric acid (H
3PO
4) corrosive liquid carries out water-bath corrosion, prepares the aluminium mask pattern; 4. again this substrate is placed in 400 ℃ the benzoic acid crystal liquation and carried out proton exchange 5 hours, prepare the graded index distribution waveguide; 5. annealing; 6. at last fall aluminium film remaining on the substrate with 70 ℃ phosphoric acid corrosion again, and make end face and polish.