Fiber Optical Parametric Oscillator SPM Suppression
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Solution Overview
Problem
In optical parametric oscillators (OPOs), high peak power of the pump light leads to self-phase-modulation in the fiber, broadening the spectrum bandwidth and reducing the conversion efficiency from pump light to signal light, making it difficult to achieve high peak power of signal light.
Innovation Solution
Minimizing the fiber length between the main amplifier and the parametric gain medium, such as using a single mode photonic crystal fiber, and inserting the main amplifier inside the OPO cavity to suppress self-phase modulation and increase conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high peak power pump light is coupled into the parametric gain medium, then the signal light generation is enhanced, but self-phase-modulation occurs in the fiber which broadens spectrum bandwidth and decreases conversion efficiency
Solution Approach 1:
The patent applies preliminary action by placing a spectral filter before the parametric gain medium to pre-select and narrow the bandwidth of the pump light. This prevents the broad spectrum from causing excessive self-phase-modulation in the fiber, thereby maintaining high conversion efficiency while still enabling high peak power signal light generation through the parametric process.
Solution Approach 2:
The patent applies local quality by using different fiber types in different locations of the system. Specifically, it uses highly nonlinear fiber (HNLF) with specific characteristics (zero dispersion wavelength, nonlinear coefficient) in the parametric gain medium location, while using standard single mode fiber for other connections. This localized optimization allows high conversion efficiency and peak power generation without excessive SPM in the critical region.
2Power
If high peak power pump light is coupled into the parametric gain medium, then the signal light generation is enhanced, but the spectrum bandwidth of pump light is broadened
Solution Approach 1:
The patent applies preliminary action by placing a spectral filter before the parametric gain medium to pre-select and narrow the bandwidth of the pump light. This prevents the broad spectrum from causing excessive self-phase-modulation in the fiber, thereby maintaining high conversion efficiency while still enabling high peak power signal light generation through the parametric process.
3Ease of operation
If a long fiber is used to connect the gain fiber and the parametric gain medium, then alignment and connection are easier, but self-phase-modulation increases and conversion efficiency decreases
Solution Approach 1:
The patent applies local quality by using different fiber types in different locations of the system. Specifically, it uses highly nonlinear fiber (HNLF) with specific characteristics (zero dispersion wavelength, nonlinear coefficient) in the parametric gain medium location, while using standard single mode fiber for other connections. This localized optimization allows high conversion efficiency and peak power generation without excessive SPM in the critical region.
Solution Approach 2:
The patent applies the intermediary principle by using a spectral filter as an intermediate component between the pump source and the parametric gain medium. This filter mediates the interaction by narrowing the pump spectrum before it enters the fiber, thereby reducing SPM effects while still allowing sufficient power to reach the gain medium for efficient signal generation.
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 peak power signal light generation with narrow bandwidth, achieving efficient wavelength tuning and increased output pulse energy, comparable to femtosecond Titanium:Sapphire lasers but at a lower cost and with greater ease of use.
Implementation Method 1
The first optical pulse from the optical source is amplified by an optical amplifier to a peak power sufficient to pump the parametric gain medium
Implementation Method 2
The operation of FOPOs is in essence based on degenerated four-wave-mixing (FWM) wherein two pump photons interact with the fiber to generate a signal photon and an idler photon
Implementation Method 3
An optical parametric oscillator (OPO) can be realized by exploiting the χ(2) nonlinear optical response in a wide range of crystals or the χ(3) nonlinear response in optical fibers
Implementation Method 4
As a pump light which has a high peak power is coupled into the parametric gain medium in the FOPO cavity, self-phase-modulation (SPM) occurs in the fiber which connects the gain fiber and the parametric gain medium. As a result, spectrum bandwidth of the pump light is broadened
Data Source
AI summary
An optical apparatus that includes an optical source that generates a first optical pulse with a first optical wavelength. The optical apparatus also includes an optical amplifier that outputs an amplified pulse. The optical apparatus also includes a first waveguide that is connected to the optical amplifier and a second waveguide. Wherein the second waveguide converts the energy of the amplified pulse into energy of a second pulse that has a second optical wavelength different from the first optical wavelength. Wherein, the following equation is satisfied: L_min≦L≦π/γP. In which a length of the first waveguide is L, a nonlinear coefficient of the first waveguide is γ, a peak power of the amplified pulse as it is received by the first waveguide is P, and a minimum length of the first waveguide is L_min or L is equal to zero.