Dual Piezo Mirror Laser Frequency Locking
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Solution Overview
Problem
Existing laser systems face challenges in maintaining a narrow linewidth due to mechanical noise and frequency drifting, particularly in widely tuneable single frequency lasers, which are essential for applications like optical sensors and communications.
Innovation Solution
A laser system employing a dual piezo-actuated mirror with a locking and scanning circuit that separates error signals for independent processing by two piezoelectric crystals, allowing optimized feedback signals for each crystal to maximize loop gain and reduce frequency modulation noise, thereby stabilizing the laser output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single feedback circuit is used to control both piezoelectric crystals, then the device complexity is reduced, but the loop gain cannot be maximized and frequency modulation noise increases
Solution Approach 1:
The feedback circuit is segmented into two independent signal processing circuits, each dedicated to controlling one piezoelectric crystal. This segmentation allows each circuit to be optimized independently for its specific crystal, maximizing loop gain for both crystals simultaneously while reducing frequency modulation noise, thereby resolving the contradiction between device complexity and frequency stability.
2Adaptability or versatility
If mechanical mounting techniques are used to allow rotation of selecting elements for frequency tuning, then the laser frequency can be tuned, but mechanical noise induces frequency drifting and broadens the linewidth
Solution Approach 1:
The patent replaces mechanical rotation of selecting elements with electronic frequency tuning by independently controlling the resonant frequencies of two piezoelectric crystals through separate feedback circuits. This substitution eliminates mechanical noise from the tuning mechanism while maintaining the ability to tune laser frequency, thereby resolving the contradiction between frequency tuning adaptability and frequency stability.
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 approach results in a laser output with a significantly narrower linewidth, reducing the frequency modulation noise to the intrinsic noise level of the reference cavity, enhancing stability and precision in frequency tuning.
Implementation Method 1
a first signal processing circuit for processing a first component of the error signal so as to provide a feedback signal for a first piezoelectric crystal of the dual piezo-actuated mirror; and a second signal processing circuit for processing a second component of the error signal so as to provide a feedback signal for a second piezoelectric crystal of the dual piezo-actuated mirror
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(b)
AI summary
A system and method that can be employed to lock and scan the output of a laser cavity (2) is described. The system and method involves the use of a signal generator for generating an error signal between an output of the laser cavity (28) and the transmission (28) of the laser through a tunable external reference cavity (3). A dual piezo-actuated mirror (6b) permits processing of the error signal (26) with separate signal processing circuits (29a, 29b) used to provide an electrical feedback signal to the two piezoelectric crystals (22, 23b). When incorporated within a laser cavity the described system and methodology can be used to lock and scan the output of the laser cavity while providing the laser output with a reduced linewidth.