Recent progress in lithium niobate based integrated optics is reviewed, emphasizing applications in the telecommunications area. Prospects for systems applications are discussed. >

Integrated optics in LiNbO/sub 3/: recent developments in devices for telecommunications

Guided-wave devices demonstrated in lithium niobate have been seen for many years as highly functional components for applications in fields such as optical communications and sensor systems. The potential for their use has been recognized by the substantial research and development effort the technology has witnessed, and the subject matter of this article is born from these endeavours. The material reviewed includes a survey of devices built, including their design, functionality, and performance, as well as parallel activities that have been undertaken in materials processing, theory, and the development of lithium niobate itself, all of which are closely linked, and all of which have played an important part in the overall development of this major branch of contemporary optics research.

https://iopscience.iop.org/article/10.1088/0034-4885/56/3/001/pdf

Lithium niobate integrated optics

Reviews the status of fiber attachment to guided wave devices. Current methods for achieving low fiber-waveguide-fiber insertion loss are discussed and techniques for aligning and permanently attaching fibers are described. >

Fiber attachment for guided wave devices

Integrated-optic components on LiNbO 3 for fiber-optical communication systems are reviewed with respect to technology, fiber coupling, and device configurations. Typical devices for communication applications, such as modulators/switches, multiplexers, switch arrays, and heterodyne receiver chips rely on electrooptically controlled waveguide structures. Their operation mechanisms and performance characteristics are described to highlight the present status of development and of system applications.

Integrated-optic devices on LiNbO 3 for optical communication

A model for digital synchronous delay line memory (DSDLM) is given, yielding limitations on the maximum number of bits that can be reliably stored for a given change in delay medium temperature and amount of medium dispersion. More than 22 million bits can be stored when single-mode optical fiber is used as the medium, but only if operated at the wavelength of minimum dispersion and by limiting thermal fluctuations to within 0.002 degrees C. A DSDLM is being constructed using such fiber, along with lithium niobate directional couplers as the switching elements. Signal regeneration errors, switch crosstalk, and polarization losses are negligible for the implementation. With a modulation frequency of 100 MHz, a single-line 2000-bit memory can be reliably operated without thermal compensation given a temperature fluctuation of <80 degrees C.

Fiber optic delay line memory.

We report the fabrication and testing of several models of a complex integrated Ti : LiNbO 3 switch array, a one-input-to-sixteen-output switch that is polarization independent for use with standard single-mode fibers. The switch array has 15 directional couplers arranged in a binary tree with four ranks. The device is fitted with connectorized single-mode fiber pigtails and housed in a package that permits convenient transport and use. The best measured losses (fiber-waveguide-fiber) are 3.0 dB for the TE polarization and 3.6 dB for the TM. Permanent attachment of the pigtails adds 0.65-dB loss. Crosstalk suppression averages 10 dB below the transmitted signal for the brightest unwanted path.

http://ieeexplore.ieee.org/iel5/50/23149/01074663.pdf

A polarization-independent 1 &#215; 16 guided-wave optical switch integrated on lithium niobate

A method is presented for calculating the wavelength sensitivity for electrooptic guided-wave stitches that work by mode interference, including directional-coupler and balanced-bridge switches. The method relies on a coupled-mode theory, using measured wavelength sensitivity of the coupling. Crosstalk is taken as the bandwidth-limiting property and is calculated by expanding in bandwidth. It is found that the wavelength sensitivity depends on the coupler gap, the amount of coupling, and the electrode configuration. Numerical examples show that switches with proper design can exhibit better than 25 dB of crosstalk with a 100- mu m bandwidth. Modulators have a still wider bandwidth. >

J.E. Watson

Papers

A polarization-independent 1 × 16 guided-wave optical switch integrated on lithium niobate

Calculated wavelength sensitivity of lithium niobate switches

J.E. Watson

Papers

A polarization-independent 1 &#215; 16 guided-wave optical switch integrated on lithium niobate

Calculated wavelength sensitivity of lithium niobate switches

A polarization-independent 1 × 16 guided-wave optical switch integrated on lithium niobate