Product Design, Manufacturing & Innovation Resources

家 » 原子布居反转

原子布居反转

1950

（图片仅供参考）

粒子数反转是指原子或分子系统中处于较高激发态的粒子数多于处于较低激发态的粒子数的一种状态。这种非平衡状态是受激辐射光放大的先决条件。如果没有粒子数反转，吸收将占主导地位，无法获得净增益，激光作用也就无法实现。

Under normal thermal equilibrium, the population of energy levels is described by the Boltzmann distribution, which dictates that lower energy states are always more populated than higher energy states. To achieve laser action, this natural state must be inverted. Population inversion is the condition where the number of atoms in an excited state, [latex]N_2[/latex], exceeds the number in a lower energy state, [latex]N_1[/latex], i.e., [latex]N_2 > N_1[/latex]. This is a necessary condition for net optical gain, as the rate of stimulated emission (proportional to [latex]N_2[/latex]) must be greater than the rate of absorption (proportional to [latex]N_1[/latex]).

实现粒子数反转需要外部能量源，这一过程称为“泵浦”。常见的泵浦方法包括光泵浦（使用闪光灯或其他激光器）、电放电（在气体激光器中）和直流注入（在半导体激光器中）。系统被“泵浦”到高能级，然后迅速衰变到寿命相对较长的“亚稳态”上激光能级。下激光能级被设计成快速衰变，以确保其保持未激发状态。这就在亚稳态上能级和快速衰变的下能级之间实现了粒子数反转。这通常使用三能级或四能级能级方案来实现，其中四能级系统效率更高，因为下激光能级不是基态，更容易保持未激发状态。

活力, Laser, 光学, 光子学

UNESCO Nomenclature: 2210

– Optics

类型

Physical Principle

中断

Foundational

用法

广泛使用

前体

受激辐射理论（爱因斯坦）
quantum mechanics and discrete energy levels (Bohr, 薛定谔)
热平衡的玻尔兹曼统计
脉塞的发展（汤斯、巴索夫、普罗霍罗夫）

应用程序

所有类型的激光器（气体激光器、固态激光器、半导体激光器）
微波激射器
光放大器
超辐射实验
原子钟

专利：

潜在创新理念

room-temperature X-ray lasers using nuclear isomers
population inversion-based cooling systems for microelectronics
efficient anti-stokes raman lasers for chemical detection
gamma-ray lasers based on controlled nuclear transitions
inversion-less lasing schemes for ultra-low threshold lasers
coherent matter-wave amplifiers (atom lasers) with population inversion
terahertz lasers for non-invasive medical diagnostics
direct solar-pumped lasers for space-based power transmission
spin-polarized lasers for spintronics applications
tunable lasers based on engineered 你给多少 population dynamics

相关术语：粒子数反转、激光、微波激射器、受激辐射、光增益、泵浦、亚稳态、非平衡态、玻尔兹曼分布、能级。

历史背景

Thermal lance cutting through steel in industrial thermodynamics application.

高温切割机制

热喷枪的温度可达3500摄氏度至4500摄氏度，远远超过传统喷枪。这种高温不仅能熔化目标材料，其喷射的纯氧还能快速氧化材料本身，使其成为燃料源的一部分。这种熔化和燃烧的结合作用使其能够切割厚钢板、混凝土和岩石。

Nuclear reprocessing facility utilizing the PUREX process for uranium and plutonium extraction.

PUREX工艺

PUREX 是“钚和铀提取回收”的缩写，是乏核燃料后处理的主要工业方法。它采用液-液萃取 (LLE) 技术，将铀和钚从高放射性裂变产物中分离出来。该工艺使用浓度为 30% 的磷酸三丁酯 (TBP) 溶液（溶于烃类稀释剂）从硝酸原料中选择性萃取铀 (VI) 和钚 (IV)。

Controlled explosion demonstrating energy release quantified in tonnes of TNT in an industrial setting.

吨TNT（能量单位）

“吨TNT”是用于量化大量能量释放（尤其是爆炸释放）的能量单位。国际协议通常将其定义为4.184吉焦耳（GJ）。该值基于TNT爆炸时的能量密度计算得出，约为4184焦耳/克。它被用作比较核武器和其他爆炸事件当量的标准参考。

原子布居反转

Research laboratory focused on superconductivity with advanced cryostat and scientists analyzing data.

超导BCS理论

Developed in 1957 by John Bardeen, Leon Cooper, and Robert Schrieffer, the BCS theory provides a microscopic explanation for conventional superconductivity. It posits that below the critical temperature ([latex]T_c[/latex]), electrons can overcome their electrostatic repulsion and form bound pairs, called Cooper pairs, through interactions with the crystal lattice (phonons). These pairs behave as bosons and can condense into a single macroscopic quantum state.

光学谐振器

光学谐振腔，或称光学谐振器，是由一系列反射镜组成的结构，能够形成光波驻波腔。在激光器中，它环绕着增益介质，提供正反馈。受激辐射产生的光在谐振腔内来回反射，多次穿过增益介质，从而实现显著的光放大，并最终形成相干输出光束。

黛博拉·诺尔

The Deborah number is a dimensionless quantity in rheology, used to characterize the fluidity of materials. It is the ratio of the relaxation time, which is an intrinsic property of the material, to the characteristic time scale of the experiment or observation. The formula is [latex]De = \frac{t_c}{t_p}[/latex], where [latex]t_c[/latex] is the relaxation time and [latex]t_p[/latex] is the observation time.

1950

1957

1958

1960

1950

1957

1959-11

1960

Solar cell equivalent circuit model analysis in an electronics lab.

太阳能电池等效电路模型

A solar cell can be modeled by an equivalent electrical circuit. The simplest model includes a current source representing the photogenerated current ([latex]I_L[/latex]), in parallel with a diode representing the p-n junction. A more accurate model adds a parallel shunt resistance ([latex]R_{sh}[/latex]) for leakage currents and a series resistance ([latex]R_s[/latex]) for contact and bulk material resistance.

Researcher measuring thermoelectric materials in a solid state physics laboratory.

热电品质因数（ZT）

The thermoelectric figure of merit "ZT", is a dimensionless quantity that measures the efficiency of a material for thermoelectric applications. It is defined as [latex]ZT = \frac{S^2 \sigma T}{\kappa}[/latex], where S is the Seebeck coefficient, [latex]\sigma[/latex] is electrical conductivity, T is absolute temperature, and [latex]\kappa[/latex] is thermal conductivity. A higher ZT value indicates a more efficient thermoelectric material.

Laboratory experiment on superconductors illustrating Ginzburg-Landau Theory applications.

金兹堡-朗道理论

Developed in 1950 by Vitaly Ginzburg and Lev Landau, this is a phenomenological theory that describes superconductivity near the phase transition. It introduces a complex order parameter, [latex]\Psi[/latex], to represent the density of superconducting electrons. The theory successfully describes effects like the Meissner effect and predicts the distinction between Type I and Type II superconductors based on a single parameter, [latex]\kappa[/latex].

Laboratory research on thermodynamic efficiency of fuel cells with scientists and equipment.

燃料电池的热力学效率

The maximum theoretical efficiency of a fuel cell is governed by the ratio of the change in Gibbs free energy ([latex]\Delta G[/latex]) to the change in enthalpy ([latex]\Delta H[/latex]) of the electrochemical reaction. This is expressed as [latex]\eta_{thermo} = \frac{\Delta G}{\Delta H}[/latex]. Crucially, fuel cells are not heat engines and are therefore not constrained by the Carnot efficiency limit, allowing for significantly higher theoretical conversion efficiencies.

Researcher analyzing supercapacitor in electrochemistry laboratory.

超级电容器

双电层电容器 (EDLC)，又称超级电容器，通过极化电解液以静电方式储存能量。与传统电池不同，它不涉及任何化学反应。它将能量储存在高表面积电极与电解质界面处形成的双电层（亥姆霍兹双层）中。这使得充电和放电速度极快，循环寿命也极长。

Superconducting magnet setup demonstrating Type II superconductors in a laboratory.

II型超导体

Theoretically predicted by Alexei Abrikosov in 1957 based on Ginzburg-Landau theory, Type II superconductors are characterized by two critical magnetic fields, [latex]H_{c1}[/latex] and [latex]H_{c2}[/latex]. Between these fields, they enter a mixed or "vortex" state, allowing partial magnetic field penetration through quantized flux tubes called Abrikosov vortices. This allows them to remain superconducting in much higher magnetic fields than Type I superconductors.