Patent Application
20090080063
(A) Field of the Invention
The present invention relates to an array waveguide and a light source using the same, and more particularly, to an array waveguide having a plurality of wavelength-converting waveguides and a light source using the same.
(B) Description of the Related Art
The poled structure having periodically inverted domains in a ferroelectric single crystal such as lithium niobate (LiNbO3), lithium tantalite (LiTaO3) and potassium titanyl phosphate (KTiOPO4) may be widely used in the optical fields such as optical storage and optical measurement. There are several methods for preparing the poled structure such as the proton-exchanging method, the electron beam-scanning method, the electric voltage applying method, etc.
U.S. Pat. No. 6,002,515 discloses a method for manufacturing a polarization inversion part on a ferroelectric crystal substrate. The polarization inversion part is prepared by steps of applying a voltage in the polarization direction of the ferroelectric crystal substrate to form a polarization inversion part, conducting a heat treatment for reducing an internal electric field generated in the substrate by the applied voltage, and then reinverting polarization in a part of the polarization inversion part by applying a reverse direction voltage against the voltage that was previously applied. In other words, the method for preparing a polarization inversion part disclosed in U.S. Pat. No. 6,002,515 requires performing the application of electric voltage twice.
U.S. Pat. No. 7,170,671 discloses a method for forming a waveguide region within a periodically domain reversed ferroelectric crystal wherein the waveguide region has a refractive index profile that is vertically and horizontally symmetric. The symmetric profile produces effective overlapping between quasi-phasematched waves, a corresponding high rate of energy transfer between the waves and a symmetric cross-section of the radiated wave. The symmetric refractive index profile is produced by a method that combines the use of a diluted proton exchange medium at a high temperature which produces a region of high index relatively deeply beneath the crystal surface, followed by a reversed proton exchange which restores the original crystal index of refraction immediately beneath the crystal surface.
U.S. Pat. No. 6,353,495 discloses a method for forming an optical waveguide element. The disclosed method forms a convex ridge portion having a concave portion on a ferroelectric single crystalline substrate, and a ferroelectric single crystalline film is then formed in the concave portion. A comb-shaped electrode and a uniform electrode are formed on a main surface of the ferroelectric single crystalline substrate, and electric voltage is applied to these two electrodes to form a ferroelectric domain-inverted structure in the film in the concave portion.
U.S. Pat. No. 6,404,797 discloses an array arrangement of several laser devices. A one- or two-dimensional array of surface emitting laser devices are formed in a first semiconductor substrate, a corresponding one- or two-dimensional array of micro-reflectors are formed on a second semiconductor substrate, and an optional nonlinear material may be positioned between the first and second substrate for frequency selection. Positions of the surface emitting laser devices and the micro-reflectors on respective semiconductor substrates are precisely defined so that each surface emitting laser device may be accurately coupled to a corresponding micro-reflector respectively when both substrates are coupled together.
One aspect of the present invention provides an array waveguide having a plurality of wavelength-converting waveguides and a light source using the same.
An array waveguide according to this aspect of the present invention comprises a ferroelectric crystal with a first polarization direction, a plurality of inverted domains positioned in the ferroelectric crystal and a plurality of wavelength-converting waveguides positioned in the ferroelectric crystal. The inverted domains have a second polarization direction substantially opposite to the first polarization direction, the wavelength-converting waveguides cross the inverted domains substantially in a perpendicular manner, and the inverted domains are configured to convert the first beam from the light-emitting module into a second beam as the first beam propagates through the wavelength-converting waveguides.
Another aspect of the present invention provides a light source comprising a light-emitting module configured to emit a first beam and an array waveguide configured to convert the first beam into a second beam. The light-emitting module includes a plurality of light-emitting units configured to emit the first beam, and the light-emitting units are positioned in an array manner. The array waveguide includes a ferroelectric crystal with a first polarization direction, a plurality of inverted domains positioned in the ferroelectric crystal and a plurality of wavelength-converting waveguides positioned in the ferroelectric crystal. The inverted domains have a second polarization direction substantially opposite to the first polarization direction, the wavelength-converting waveguides cross the inverted domains substantially in a perpendicular manner, and the inverted domains are configured to convert the first beam from the light-emitting module into the second beam as the first beam propagates through the wavelength-converting waveguides.
The objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which:
The array waveguide 40A includes a ferroelectric crystal 42 with a first polarization direction, a plurality of inverted domains 44 positioned in the ferroelectric crystal 42, a plurality of wavelength-converting waveguides 46 positioned in the ferroelectric crystal 42, and a plurality of stripes 50 positioned right on the wavelength-converting waveguides 46. In particular, the refractive index of the stripes 50 is higher than that of the wavelength-converting waveguides 46. The inverted domains 44 have a second polarization direction substantially opposite to the first polarization direction, the wavelength-converting waveguides 46 cross the inverted domains 44 substantially in a perpendicular manner, and the inverted domains 44 are configured to convert the first beam 14 from the light-emitting module 20 into the second beam 16 as the first beam 14 propagates through the wavelength-converting waveguides 46. Preferably, the substrate 22 has a first alignment key 26, and the ferroelectric crystal 42 has a second alignment key 48.
In particular, the first inverted domains 44A and the first wavelength-converting waveguide 46A are used to convert the first beam 14 from the light-emitting module 20 into the red light 16A, the second inverted domains 44B and the second wavelength-converting waveguide 46B are used to convert the first beam 14 from the light-emitting module 20 into the green light 16B, and the third inverted domains 44C and the third wavelength-converting waveguide 46C are used to convert the first beam 14 from the light-emitting module 20 into the blue light 16C.
The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.
