Method for fabricating low-loss optically active device

Details Method for fabricating low-loss optically active device Method for fabricating low-loss optically active device

1998-02-26

2001-04-03

Angebranndt, Martin (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Imaging affecting physical property of radiation sensitive...

Making named article

C430S394000, C216S024000, C385S005000, C385S122000, C385S132000

Reexamination Certificate

active

06210867

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical devices and to processes for fabricating optical devices generally, and, more particularly, to low-loss optically active devices exhibiting reduced losses and to processes of fabricating optically active optical devices.
2. Description of the Related Art
In forming optically active devices such as an optical modulator or an optical switch using optical polymer, an optical waveguide formed in the device is constituted of cores and upper and lower clads surrounding the cores. Here, the refractive index of the material used for the core is always greater than the refractive index of materials used for the clads. This difference in refractive indices makes the light passing through the core travel along the waveguide due to total internal reflection. Optical polymer is conventionally used in fabricating optically active devices non-linear characteristics. Typically, all core regions of the waveguide formed in the device are made of non-linear optical polymer. An exemplary structure may be found, for example, in the Electro-optic Channel Waveguide of J. I. Thackara, et alii, U.S. Pat. Nos. 5,006,285 and 5,007,696. If, as indicated for example, by the Nonlinear Optical Device For Controlling A Signal Light By A Control Light of K. Tajima, U.S. Pat. No. 5,191,630, all of the core regions of the waveguide forming an active device are made of non-linear optical material such as a non-linear optical polymer, we have noticed that the overall device loss characteristics are degraded. The waveguiding loss of a waveguide made of non-linear optical polymer exhibits a characteristic of about 0.5-1.0 dB/cm, and the waveguiding loss of the waveguide made of linear optical polymer exhibits a characteristic of about 0.1-0.2 dB/cm. Therefore, in the case of forming a waveguide having the same length and configuration with each other, a waveguide made entirely of only the non-linear optical polymer have disadvantages due to the substantial, and in our opinion unnecessary injection losses of the device, compared to the case of forming a waveguide made of the linear optical polymer. Directional coupler type optical switches and conventional Mach-Zehnder type optical modulators (e.g., the Hybrid All Optical Silica Waveguide Modulator Using Non-linear Electro-optic Components of J. Leonard, U.S. Pat. No. 5,546,480; the Mach-Zehnder Type Electro-optic Polymer Modulator In Which An Initial Output State can Be Controller By Post-photobleaching, of W. Y. Hwang, et alii, U.S. Pat. No. 5,692,075), as well as such devices as the Capillaiy Non-linear Optical Waveguide Device of L. M. Hayden, U.S. Pat. No. 4,887,884, conventionally have all regions in the waveguide including the electrode regions, formed of non-linear optical polymer that exhibits a comparatively higher optical loss than does linear optical polymer; consequently, the overall injection loss of the device is substantially increased.
SUMMARY OF THE INVENTION
It is therefore, one object of the present invention to provide low-loss optically active devices exhibiting reduced losses and processes for fabricating optically active optical.
It is another object to provide optically active devices that exhibit reduced waveguiding losses.
It is still another object to provide processes for forming waveguide cores by injecting non-linear optical polymer into only a waveguide region where a non-linear effect occurs.
It is yet another object to provide a process for fabricating low-loss optically active devices using optical polymer for reducing the waveguiding losses of waveguides in comparison devices formed with all core regions of the waveguide made of non-linear optical polymer.
It is still yet another object to provide low-loss optically active devices and processes for fabricating low-loss optically active devices constructed with only the core regions of the waveguide where optical modulation effects occur being formed of non-linear optical polymer.
It is also an object to provide low-loss optically active devices and processes for fabricating low-loss optically active devices constructed with only the core regions of the waveguide where optical modulation effects occur being formed of non-linear optical polymer, and with the waveguide of the remaining core regions being formed of linear optical polymer.
It is a further object to provide active optical devices and processes for fabricating active optical devices with opposite waveguide regions made of cores of linear optical polymer, feeding an intervening active or modulating region made of a non-linear polymer.
These and other objects may be achieved with optically active devices and a process for fabricating optically active devices that have an optical waveguide constructed of an optical waveguide core region (i.e., a non-linear core, or active, region) operating to produce a non-linear effect when waveguiding an optical signal, and an optical waveguide core region (i.e., a linear core, or waveguide, region) that does not require a non-linear effect while conducting an optical signal to, or from, the active region. A lower clad layer is formed on a substrate with a refractive index that is lower than the material of the waveguide core regions and an optical transparency. A linear optical polymer layer is then formed on the lower clad layer by coating linear optical polymer having a refractive index lower than the material of the lower clad layer. A first metal layer is then formed at a region on the lower clad layer, other than at those regions where the waveguide is to be disposed. The linear optical polymer layer without the first metal layer formed thereon is etched. A non-linear optical polymer layer is formed on the substrate having the non-linear core region. The non-linear optical polymer layer that is stacked higher than the waveguide core regions is removed, and the first metal layer is removed. A second metal layer is formed on that part of the waveguide from which the first metal layer has been removed, and the linear optical polymer of the non-second metal layer portion is removed. An upper clad layer is formed on the substrate with the linear optical polymer by using a material that has both a refractive index that is lower than the waveguide core regions and optical transparency.
Preferably, the linear optically polymer is a material that is optical transparent at the wavelength of the light being used, and that has an optical waveguiding loss that is lower than that of the non-linear optical polymer. Also, electrodes may be formed on, beneath, or both on and beneath the region made of the non-linear polymer to provide the non-linear effect thereto.


REFERENCES:
patent: 3842289 (1974-10-01), Yariv et al.
patent: 3920314 (1975-11-01), Yajima
patent: 4887884 (1989-12-01), Hayden
patent: 5006285 (1991-04-01), Thackara et al.
patent: 5007696 (1991-04-01), Thackara et al.
patent: 5103492 (1992-04-01), Ticknor
patent: 5181262 (1993-01-01), Gerardus et al.
patent: 5191630 (1993-03-01), Tajima
patent: 5202786 (1993-04-01), Boyle et al.
patent: 5255334 (1993-10-01), Mak et al.
patent: 5282078 (1994-01-01), Horsthuis
patent: 5315422 (1994-05-01), Utaka et al.
patent: 5359679 (1994-10-01), Tanaka et al.
patent: 5371817 (1994-12-01), Revelli, Jr. et al.
patent: 5376506 (1994-12-01), Ehrfeld et al.
patent: 5546480 (1996-08-01), Leonard
patent: 5555326 (1996-09-01), Hwang et al.
patent: 5617499 (1997-04-01), Brueck et al.
patent: 5692075 (1997-11-01), Hwang et al.
patent: 5703975 (1997-12-01), Miller et al.
patent: 5712935 (1998-01-01), Miyakawa
patent: 5788856 (1998-08-01), Kuhn
patent: 0 477 898 A2 (1991-09-01), None
patent: 6-067230 (1991-05-01), None
patent: 5-127207 (1993-05-01), None
patent: 6-214274 (1994-08-01), None
patent: 08146475 (1996-07-01), None
patent: WO 96/42027 (1996-12-01), None
“Optical Integrated Circuit”, Nishihara et al., issued Aug. 20, 1993, pp.198-203. (In Japanese).
Elliott, David J., “Integrated Circuit Fabrication Technology”, McGraw-Hill pp. 4-9,26-31 & 304-309, 1982.

Affiliated with

Also associated with

Rating

Method for fabricating low-loss optically active device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for fabricating low-loss optically active device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for fabricating low-loss optically active device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2513927