Organic DFB Laser Structure for Low-Threshold Quasi-CW Operation
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Solution Overview
Problem
The operation of organic solid-state lasers under continuous-wave (cw) or quasi-cw excitation is challenging due to the accumulation of long-lived triplet excitons and charge carriers, leading to increased absorption loss and emission quenching, which raises the lasing threshold and can stop lasing completely.
Innovation Solution
The development of organic laser diodes with a distributed feedback (DFB) structure and a BSBCz:CBP blend film, which suppresses triplet exciton formation and absorption loss, allowing for quasi-cw operation at high repetition rates without the need for triplet quenchers, and encapsulation to reduce thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If organic solid-state lasers operate under continuous-wave or quasi-cw excitation, then lasing can be achieved, but triplet exciton accumulation causes increased absorption loss and emission quenching, raising the lasing threshold
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 in the organic gain medium, preventing their accumulation and the associated absorption losses, thereby enabling continuous-wave operation without threshold degradation
Solution Approach 2:
Oxygen acts as an intermediary substance that mediates between the triplet excitons and the lasing process. By introducing oxygen into the organic laser cavity, it serves as a triplet quencher that converts harmful triplet excitons into singlet states, eliminating their detrimental effects on lasing threshold and enabling stable continuous-wave operation
2Duration of action of moving object
If triplet quenchers are introduced to reduce absorption loss, then continuous-wave operation is enabled, but device complexity increases
Solution Approach 1:
The patent employs oxygen, which serves multiple functions simultaneously: it acts as a triplet quencher to eliminate triplet excitons, provides optical transparency in the lasing wavelength range, and can be easily introduced into the device structure through simple encapsulation or filling techniques, thereby enabling continuous-wave operation without significantly increasing device complexity
Solution Approach 2:
The patent utilizes oxygen to create a specific atmospheric environment within the laser device that is inert toward the lasing process itself (does not absorb lasing wavelength) but active toward triplet exciton quenching. This selective chemical environment enables continuous-wave operation while maintaining relatively simple device architecture
3Productivity
If high repetition rates are achieved, then productivity increases, but thermal degradation and photodegradation increase
Solution Approach 1:
The patent converts the potentially harmful effect of high-intensity continuous excitation into a benefit by using oxygen as a triplet quencher. The oxygen eliminates triplet excitons that would otherwise cause singlet-triplet annihilation and thermal degradation, thereby enabling high repetition rate operation (up to 8 MHz) while actually reducing photodegradation through the quenching mechanism
4Use of energy by moving object
If lasing threshold is reduced, then energy efficiency improves, but achieving low threshold while maintaining continuous-wave operation is challenging
Solution Approach 1:
The patent extracts triplet excitons that would otherwise cause absorption losses and increase the lasing threshold. By removing these harmful excitons through oxygen quenching, the system achieves both low lasing threshold (high energy efficiency) and stable continuous-wave operation simultaneously
Solution Approach 2:
Oxygen acts as an intermediary that enables the system to achieve low lasing threshold by quenching triplet excitons. This intermediary substance reduces the energy barrier for lasing initiation while maintaining continuous-wave operation capability, resolving the apparent contradiction between threshold reduction and continuous operation
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
Achieves the highest reported repetition rate of 8 MHz and lowest lasing threshold of 0.25 μJ cm−2, with stable operation and reduced photodegradation, demonstrating the potential for continuous-wave organic semiconductor lasers.
Implementation Method 1
the optical resonator structure is composed of a distributed feedback (DFB) structure
Implementation Method 2
at least one light amplification layer by stimulated emission
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.