Pass-Through Pump Laser Diode in Doped Fiber Amplifiers
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Solution Overview
Problem
Existing fiber amplifiers face limitations in size and cost due to the need for multiple optical components, particularly in doped fiber amplifiers where multiple pump laser injections are required.
Innovation Solution
A fiber amplifier system that uses a pass-through laser diode with an active section generating pump light in response to an electrical drive signal, eliminating the need for a coupler to couple pump light into the optical path of the input signal light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple pump laser injections are required in conventional fiber amplifiers, then effective signal amplification is achieved, but the number of optical components increases leading to larger size and higher cost
Solution Approach 1:
The patent combines multiple pump laser functions into a single laser diode device. The laser diode generates multiple wavelengths of pump light (e.g., 980nm and 1480nm) simultaneously through its active section, eliminating the need for separate pump laser sources and their associated coupling components. This merging reduces the total number of optical components while maintaining the effectiveness of multiple pump injections for signal amplification.
Solution Approach 2:
The single laser diode is designed to perform multiple functions by generating different wavelengths of pump light. The active section of the laser diode can emit pump light at different wavelengths (such as 980nm and 1480nm) that correspond to different energy transitions in the erbium-doped fiber. This multi-functionality allows one device to replace what would traditionally require multiple specialized pump laser sources.
2Reliability
If multiple optical components are used for pump laser injections, then pump light can be effectively coupled into the optical path, but the physical size of the amplifier increases
Solution Approach 1:
The patent merges the pump light generation and coupling functions into a single integrated laser diode device. By generating multiple wavelengths of pump light within one device and directly coupling them into the optical path through its output facet, the design eliminates the need for separate coupling components such as dichroic mirrors, beam combining optics, and alignment mechanisms. This integration significantly reduces the physical volume required for the amplifier while maintaining effective pump light coupling.
3Power
If multiple pump laser chips are used, then adequate pump power is provided, but the cost of the amplifier increases
Solution Approach 1:
The laser diode is designed as a universal pump source capable of providing adequate pump power through multiple wavelengths. The active section can generate pump light at different wavelengths (e.g., 980nm and 1480nm) that both contribute to erbium ion excitation. This single multi-functional device provides the necessary pump power that would traditionally require multiple separate pump laser chips, thereby reducing the overall cost while maintaining adequate power levels for effective signal amplification.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration simplifies the system by reducing the number of required optical components, potentially leading to smaller size and lower costs while maintaining effective signal amplification.
Implementation Method 1
The active section is configured to generate pump light in response to injection of the electrical drive signal into the active section. The pump light has a pump wavelength different from the signal wavelength.
Implementation Method 2
Photons of the optical signal interact with the energized ions, causing the ions to give up some of their energy in the form of photons at the same wavelength as the photons of the optical signal, with the ions returning to a lower energy state. The optical signal is thereby amplified as it passes through the doped fiber.
Data Source
AI summary
An amplifier operable with an electric drive signal can amplify signal light having a signal wavelength. A laser diode has an active section with input and output facets. The facets are in optical communication with the signal light and are configured to pass the signal light through the laser diode. The active section is configured to generate pump light in response to injection of the electrical drive signal into the active section. The pump light has a pump wavelength different from the signal wavelength. A doped fiber doped with an active dopant is in optical communication with the signal light and is in optical communication with at least a portion of the pump light from the laser diode. The pump wavelength of the pump light is configured to interact with the active dopant of the fiber and thereby amplify the signal light.