Detachable 400-MHz acousto-optic phase modulator for a single-mode optical fiber.

Area of Science:

• Optoelectronics
• Acousto-optic devices
• Fiber optics

Background:

• Phase modulators are crucial components in optical systems.
• Existing modulators face limitations in efficiency and frequency response.
• Acoustic wave interaction with optical fibers offers a promising modulation approach.

Purpose of the Study:

• To design and fabricate a novel single-mode-fiber phase modulator.
• To investigate the performance of an acousto-optic fiber phase modulator.
• To utilize a glass capillary tube for enhanced acoustic wave coupling.

Main Methods:

• Constructed a phase modulator by contacting a single-mode fiber with a lapped glass capillary tube.
• Fabricated a thin-film zinc oxide (ZnO) transducer onto the capillary.
• Launched acoustic waves from the ZnO transducer to interact with the fiber core.
• Measured the device's frequency response and phase shift.

Main Results:

• The device operated at a center frequency of 416 MHz with a 14 MHz bandwidth.
• Achieved a maximum phase shift of 0.033 radians per square root milliwatt.
• Recorded a largest phase shift of 1.2 radians at 1.3 W input electrical power.

Conclusions:

• The developed fiber phase modulator demonstrates effective acousto-optic modulation.
• The glass capillary design facilitates efficient acoustic wave coupling to the fiber.
• This device shows potential for high-frequency optical modulation applications.