Laser Arrangement With External Cavity And Voltage Monitoring

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Solution Overview

Problem

Current laser measurement techniques are complex and require additional optical components for wavelength stabilization, leading to increased size and potential interference, while simplifying the measurement of emission wavelength and material properties remains a challenge.

Innovation Solution

A laser arrangement with an external cavity and integrated optical waveguide that uses the voltage at the active section to detune the emission wavelength, eliminating the need for additional feedback signals and enabling a compact design by leveraging the interference of light within the cavity to stabilize the wavelength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional optical components (e.g., filters or photodiodes) are used to generate feedback signals for wavelength stabilization, then wavelength stabilization is achieved, but device complexity and size increase

Engineering Contradiction:
Improvewavelength stabilizationVSAvoidnumber of optical components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The laser diode's active section serves dual purposes: generating light and providing wavelength stabilization feedback. The voltage at the active section is used directly as the monitor signal, eliminating the need for separate optical components. The system uses itself (the active section's voltage) to stabilize its own wavelength.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The active section of the laser diode performs multiple functions: it generates the laser light and simultaneously provides the monitor signal for wavelength stabilization. This multi-functionality reduces the need for separate components and simplifies the overall device structure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Measurement precision

If additional optical components are added for wavelength measurement, then measurement capability is improved, but compact design is compromised

Engineering Contradiction:
Improvewavelength measurement capabilityVSAvoiddevice size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The wavelength measurement functionality is merged with the existing laser structure by using the voltage at the active section as the monitor signal. This combines the light generation and wavelength monitoring functions into a single integrated structure, enabling compact design.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The laser diode's active section provides its own voltage signal for wavelength measurement without requiring external sensing components. This self-service approach eliminates additional volume requirements for separate measurement devices.

Inventive Principle:
Principle #25Self-service

3Object-affected harmful factors

If optical filters are added to avoid interference, then interference is reduced, but device complexity and size increase

Engineering Contradiction:
Improveoptical interferenceVSAvoidnumber of optical components
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The need for optical filters to manage interference is extracted and eliminated by using the electrical voltage at the active section as the monitor signal. This approach removes the harmful requirement for additional optical filtering components while maintaining interference management capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The optical filtering approach is replaced with an electrical measurement approach. Instead of using optical filters to manage interference, the patent uses electrical voltage measurement at the active section, substituting optical components with electrical sensing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 allows for high output power and compact design with reduced interference, enabling precise wavelength measurement and material property determination without additional optical components, facilitating the development of chip-integrated measuring devices.

Implementation Method 1

The light reflected back interferes with the light in the laser cavity, which has an influence on the electrical voltage on an active section of the laser

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 2

an external cavity in a free-beam arrangement that interacts with a laser, with the electrical voltage at an active section of the laser being used to determine a distance

Methodology Applied
Scientific EffectOptical feedback: Feedback

Implementation Method 3

the external cavity having an optical waveguide coupled to the laser

Methodology Applied
Scientific EffectOptical waveguide: Waveguide (optics)

Data Source

PatentEP3414804B1Laser arrangement, method for controlling a laser and measuring method
Publication Date: 2021.08.25 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3414804B1 patent drawingFigure 1

AI summary

The invention relates to a laser arrangement, comprising a laser (2) having a laser cavity (20); a least one cavity (30) external to the laser (2) which reflects one part of the light emitted by the laser (2) back into the laser cavity (20); a voltage measuring device (4) for measuring a voltage on an active section (21) of the laser (2), wherein an imbalance of the emission wave length of the laser (2) and/or a property of a material adjacent to the external cavity (30) can be determined. According to the invention, the external cavity (30) comprises an optical waveguide (34) coupled to the laser (2). The invention also relates to a method for controlling a laser and to a measuring method.