Tunable Light Source Using Frequency-Line Filtering for Fast Tuning
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Solution Overview
Problem
Existing tunable light sources with external cavity laser arrangements face challenges in achieving rapid frequency tuning, high accuracy, and narrow linewidth due to transient frequency noise and lengthy settling times, limiting their applicability in applications requiring broad spectral range and precise frequency control.
Innovation Solution
A light source design incorporating multiple frequency generators and filters that rapidly and accurately tune the output frequency without generating transient noise, featuring an emitter assembly, first and second frequency generators, and filters to produce a source beam with a narrow linewidth and broad spectral range, allowing for quick adjustment to a target frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an external cavity laser arrangement with intra-cavity frequency adjuster is used to tune the output frequency, then the frequency can be selectively tuned over a tunable range, but the tuning time increases to the second to millisecond range due to transient frequency noise settling time
Solution Approach 1:
The patent segments the frequency generation process into multiple discrete frequency lines generated by frequency generators, rather than using a single continuous tuning mechanism. Each frequency line can be independently selected and combined, enabling rapid switching between frequencies without the need for mechanical adjustment and settling time.
Solution Approach 2:
The patent replaces the mechanical intra-cavity frequency adjuster (movable grating) with an electronic frequency generation system using frequency generators and filters. This substitution eliminates the mechanical movement and associated transient noise, reducing tuning time from seconds to sub-millisecond range.
2Adaptability or versatility
If an external cavity laser arrangement with movable grating is used for frequency tuning, then the output frequency can be adjusted, but transient frequency noise is generated that requires time to settle down
Solution Approach 1:
The patent replaces the mechanical movable grating system with an electronic frequency generation approach using frequency generators and filters. This eliminates mechanical vibrations and transient noise associated with moving parts, providing frequency adjustment without compromising frequency stability.
Solution Approach 2:
The patent introduces frequency filters as intermediaries between the frequency generators and the output. These filters selectively pass only the desired frequency line while blocking others, ensuring clean frequency output without transient noise from mechanical adjustment mechanisms.
3Measurement precision
If on-board metrology is used to monitor the output frequency to determine absolute frequency accuracy, then the frequency can be verified to match the target frequency, but the system complexity increases
Solution Approach 1:
The patent implements self-service frequency generation where the frequency generators are configured to directly produce frequency lines at or near the target frequency. The system inherently generates the required frequency without needing complex external metrology equipment, reducing system complexity while maintaining accuracy.
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
Enables rapid and accurate tuning of the light source over a broad spectral range with minimal transient noise, achieving sub-millisecond tuning times and high absolute frequency accuracy, suitable for applications requiring precise frequency control and narrow linewidth.
Implementation Method 1
the first frequency generator receives the emitter beam and generates a first generator beam that consists of a plurality of discrete, spaced apart, first frequency lines
Implementation Method 2
a first filter that filters the first generator beam to transmit a first filter beam that includes only one of the first frequency lines
Implementation Method 3
a second frequency generator that receives the first filter beam and converts the first filter beam into a second generator beam that consists of a plurality of discrete, spaced apart second frequency lines
Implementation Method 4
a second filter that filters the second generator beam to provide a second filter beam that includes only one of the second frequency lines
Data Source
AI summary
A tunable light source (10) that generates a source beam (12) having a tunable source frequency (12a) includes an emitter assembly (14), a first frequency generator (16), and a first filter (18). The emitter assembly (14) emits an emitter beam (14a), and the first frequency generator (16) receives the emitter beam (14a) and generates a plurality of first frequency lines (16b). The first filter (18) filters the first frequency lines (16b) to transmit a first filter beam (18a) that includes only one of the first frequency lines (16b). The light source (10) can include a second frequency generator (20) that converts the first filter beam (18a) into a plurality of second frequency lines (20b), and a second filter (22) that filters the second frequency lines (20b) to provide a second filter beam (22a) having the source frequency (12a).