This paper reviews the direct bonding technique focusing on the waveguide optical isolator application. A surface activated direct bonding technique is a powerful tool to realize a tight contact between dissimilar materials. This technique has the potential advantage that dissimilar materials are bonded at low temperature, which enables one to avoid the issue associated with the difference in t...

This paper describes a new, compact, waveguide thermal isolator. The isolator is based on a recently developed microwave bandgap joint, a periodic structure which suppresses microwave fields propagating between two parallel conducting surfaces. When such a structure is placed between a pair of waveguide flanges, the flanges can be separated by a few percent of a wavelength before the leakage an...

Integrated optical isolators will become necessary as optical networks continue to grow and the need for monolithic integration and greater functionality increases. This thesis presents a design for a polarization independent isolator which can be monolithically integrated with semiconductor lasers. Theory and measurements are used to select a material for the isolator. A polarization independe...

A ring isolator is demonstrated for the first time by directly bonding a cerium-substituted yttrium iron garnet (Ce:YIG) onto a silicon ring resonator using oxygen plasma enhanced bonding. The silicon waveguide is 600 nm wide and 295 nm thick with 500-nm-thick Ce:YIG on the top to have reasonable nonreciprocal effect and low optical loss. With a radial magnetic field applied to the ring isolato...

Array-type optical devices are important for wavelength-division multiplexing optical communication system to achieve small footprint, mass production, and reliability. For fabricating transmitter module in an array configuration, it is difficult to achieve a passive alignment of isolator, collimating lens, and laser diode. To facilitate array isolator integration, a waveguide collimator is pro...

The experimental demonstration of a novel integrated optical isolator concept is presented. By using a transversely magnetized ferromagnetic metal as the electric contact of an active waveguide structure, the transverse magneto-optic Kerr effect induces nonreciprocal loss of the TM guided mode. Based on this principle we designed, fabricated and characterized the first version of an optical iso...

We report on a novel technique to realize a waveguide optical isolator without using conventional magneto-optical materials and external magnets. The simulations are repeatedly performed using Beam Propagation Method (BPM) to confirm the accuracy. The simulation results show that the forward and backward propagations reach 2.54 and 15.68 dB, respectively.

A bimodal planar waveguide segment of specific length and thickness between two thinner single mode sections can serve as an interferometer. Depending on the phase gain of the two modes in the thick region, these fields can interfere destructively or constructively at the transition from the bimodal to the single mode section. We employ this geometry to realize a simple magnetooptic isolator co...

A waveguide optical isolator realized by adhesive bonding of a garnet die, containing a Ce:YIG magneto-optic layer, on a silicon-on-insulator waveguide circuit is demonstrated. The die was bonded on top of an asymmetric Mach-Zehnder interferometer using a 100nm thick DVS-BCB adhesive bonding layer. A static magnetic field applied perpendicular to the light propagation direction results in a non...

The recent development of on chip integration of magneto-optic isolators is reviewed. Two major categories of structural designs for waveguide isolator (nonreciprocal mode conversion and nonreciprocal phase shift) have both merits and short comings for integration. The advances in integration techniques and materials related developments in the last decade are a big step towards monolithic inte...