Cat's-Eye Swept Laser with Tilt-Tuned Filter for High-Duty OCT

Solution Overview

Problem

Existing swept-source optical coherence tomography (SS-OCT) systems face limitations in sweep speed and duty cycle due to four-wave mixing effects in semiconductor optical amplifiers, leading to reduced effective repetition rates and performance inefficiencies.

Innovation Solution

A tunable laser architecture using a cat's-eye configuration with a transmissive tilt tuned filter and a thin film bandpass filter, controlled by an angle control actuator, such as a galvanometer, to achieve high-speed wavelength scanning and improved duty cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a laser is mode-locked to generate femtosecond pulses for OCT and spectroscopy, then the spectral bandwidth and imaging resolution are improved, but the laser becomes highly nonlinear and unstable with significant pulse-to-pulse energy fluctuations

Engineering Contradiction:

Improveimaging resolutionVSAvoidlaser stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the laser operation into two distinct modes: a stable continuous-wave (CW) mode for reliable laser output, and a mode-locked mode for high-resolution spectroscopy and OCT. The system selectively operates in these segments based on the application requirements, rather than attempting to achieve both simultaneously in a single operational mode.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic switching between different laser operating modes using an acousto-optic modulator (AOM) or electro-optic modulator (EOM). The laser can be rapidly switched between CW and mode-locked states, allowing the system to adapt its characteristics in real-time based on the specific measurement requirements.

Inventive Principle:

Principle #15Dynamics

2Reliability

If a laser operates in continuous-wave mode for stability, then the laser reliability is improved, but the spectral bandwidth and imaging resolution deteriorate

Engineering Contradiction:

Improvelaser stabilityVSAvoidimaging resolution

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent creates a universal laser system that can perform multiple functions by switching between operating modes. The same laser source provides both stable CW operation for general applications and high-resolution mode-locked operation for spectroscopy and OCT, eliminating the need for separate laser systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements dynamic switching between different laser operating modes using an acousto-optic modulator (AOM) or electro-optic modulator (EOM). The laser can be rapidly switched between CW and mode-locked states, allowing the system to adapt its characteristics in real-time based on the specific measurement requirements.

Inventive Principle:

Principle #15Dynamics

3Power

If a laser provides high peak power for nonlinear optics and multiphoton microscopy, then the imaging capability is improved, but the average power fluctuates significantly reducing reliability

Engineering Contradiction:

Improvepeak powerVSAvoidaverage power stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent segments the laser operation into two distinct modes: a stable continuous-wave (CW) mode for reliable laser output, and a mode-locked mode for high-resolution spectroscopy and OCT. The system selectively operates in these segments based on the application requirements, rather than attempting to achieve both simultaneously in a single operational mode.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs periodic pulse generation through mode-locking, where ultrashort pulses are generated at regular intervals. This periodic action provides high peak power during the pulse while maintaining a controlled average power through the repetition rate, enabling nonlinear optical processes while managing thermal and damage effects.

Inventive Principle:

Principle #19Periodic action

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

The cat's-eye configuration enhances sweep speed and duty cycle, providing stable, high-resolution imaging capabilities suitable for applications like retinal imaging and spectroscopy with reduced loss and improved polarization management.

Implementation Method 1

A mode-locked laser generates femtosecond pulses with a spectral bandwidth that enables high-resolution spectral-domain optical coherence tomography (SD-OCT) and femtosecond stimulated Raman spectroscopy (FSRS)

Methodology Applied

Scientific EffectMode-locking:

Implementation Method 2

lasers that operate in continuous-wave (CW) mode are stable and reliable

Methodology Applied

Scientific EffectContinuous-wave laser operation:

Implementation Method 3

lasers that provide the high peak power necessary for nonlinear optical processes and multiphoton microscopy

Methodology Applied

Scientific EffectNonlinear optics:

Implementation Method 4

high peak power necessary for nonlinear optical processes and multiphoton microscopy

Methodology Applied

Scientific EffectMultiphoton absorption:

Data Source

PatentEP4493887B1Cat's-eye swept source laser for oct and spectroscopy

Publication Date: 2026.05.06 KINEOLABS INC

Figure 1A~3
Figure 1B
Figure 2C~4

AI summary

A tunable or swept laser architecture that is appropriate for swept source optical coherence tomography and other applications including spectroscopy employing a cat's-eye configuration with a preferably transmissive tilt tuned interference thin film filter.