Mode-selective detection of optical guided waves by integrated metal-oxide-metal structures

Area of Science:

• Optoelectronics
• Photonics
• Materials Science

Background:

• Evanescent coupling is crucial for integrating optical and electronic components.
• Metal-oxide-metal tunnel junctions offer unique electronic properties for signal detection.

Purpose of the Study:

• To demonstrate a metal-oxide-metal (Al-AlOx-Al) tunnel junction for detecting guided radiation.
• To investigate the polarization sensitivity of the device for optical sensing applications.

Main Methods:

• Fabrication of an Al-AlOx-Al tunnel junction directly on a planar ion-exchange glass waveguide.
• Utilizing evanescent coupling to transfer energy from the waveguide to the tunnel junction.
• Measuring photocurrent generated by internally photoemitted carriers.

Main Results:

• The tunnel junction successfully detects guided radiation through evanescent coupling.
• The device exhibits polarization sensitivity due to differential metallic absorption of TM-polarized modes.
• Achieved a high TM selectivity of 32 dB in a simple device configuration.

Conclusions:

• Metal-oxide-metal tunnel junctions are effective for detecting guided light in waveguides.
• The demonstrated device offers a simple and selective method for optical sensing.
• Potential applications in integrated optoelectronic devices and optical communication systems.