Organic Thin-Film DFB Laser for Continuous-Wave Lasing Stability
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Solution Overview
Problem
The challenge in achieving continuous-wave (cw) lasing in organic solid-state lasers is exacerbated by the accumulation of long-lived triplet excitons and charge carriers under high repetition rate optical excitation, leading to increased absorption loss and emission quenching, which raises the lasing threshold and can stop lasing altogether.
Innovation Solution
The development of a continuous-wave organic thin-film distributed feedback laser using a BSBCz:CBP blend film with a second-order grating structure, which suppresses triplet exciton formation and absorption loss, allowing for quasi-cw and cw operation without the need for triplet quenchers, and incorporates an encapsulation technique to reduce thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If high repetition rate optical excitation is used to achieve continuous-wave lasing, then the lasing operation is maintained, but triplet excitons and charge carriers accumulate leading to increased absorption loss and emission quenching
Solution Approach 1:
The patent extracts and removes triplet excitons from the system using oxygen as a triplet quencher. The oxygen molecules selectively interact with and quench triplet excitons, preventing their accumulation and the associated absorption losses, thereby enabling continuous-wave operation without energy loss degradation
Solution Approach 2:
Oxygen acts as an intermediary substance that mediates between the triplet excitons and the lasing process. It provides a pathway for triplet exciton removal without directly interfering with the singlet exciton lasing mechanism, thus maintaining lasing efficiency while preventing energy loss
2Duration of action of stationary object
If triplet quenchers are introduced to reduce absorption loss, then continuous-wave operation becomes possible, but device complexity increases
Solution Approach 1:
The patent employs oxygen, which is naturally present in the environment, as the triplet quencher. This eliminates the need for complex integrated triplet quenching mechanisms or additional specialized components, as the system utilizes ambient oxygen to maintain continuous-wave operation, thereby avoiding increased device complexity
Solution Approach 2:
The patent utilizes the inert nature of oxygen in terms of its selective chemical reactivity - it selectively quenches triplet excitons without interfering with the lasing process. This selective inertness allows simple device design while achieving the desired continuous-wave operation through environmental oxygen
3Power
If optical excitation is used to achieve lasing, then lasing threshold can be reached, but thermal degradation occurs reducing operational stability
Solution Approach 1:
The patent employs periodic pulsed optical excitation rather than continuous excitation. This periodic action allows the gain medium to cool down between pulses, preventing thermal accumulation and degradation, while still achieving continuous-wave lasing operation through high repetition rate pulsing
Solution Approach 2:
The patent implements protective measures beforehand by using oxygen to quench triplet excitons before they can contribute to thermal degradation. This prior cushioning against triplet-related heating and degradation pathways maintains operational stability while achieving the required lasing power
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 achieves the highest reported repetition rate of 8 MHz and the lowest lasing threshold of 0.25 μJ/cm², with operational stability and reduced degradation, demonstrating a significant step towards realizing electrically pumped organic laser diodes.
Implementation Method 1
The laser according to Item 5, wherein the optical resonator structure is composed of a second-order Bragg scattering region surrounded by the first-order Bragg scattering region
Implementation Method 2
at least one light amplification layer by stimulated emission
Implementation Method 3
incorporates an encapsulation technique to reduce thermal degradation
Data Source
AI summary
Disclosed are a current excitation type organic semiconductor laser containing a pair of electrodes, an organic laser active layer and an optical resonator structure between the pair of electrodes and a laser having an organic layer on a distributed feedback grating structure. The lasers include a continuous-wave laser, a quasi-continuous-wave laser and an electrically driven semiconductor laser diode.