Related Experiment Video
Updated: Jun 12, 2026
12:18
Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Naturally phase-matched second-harmonic generation in a whispering-gallery-mode resonator
J U Fürst1, D V Strekalov, D Elser
1Max Planck Institute for the Science of Light, Erlangen, Germany.
Physical Review Letters
|May 21, 2010
Summary
Researchers achieved 9% conversion efficiency for optical frequency doubling using a lithium niobate resonator. This low-power, high-efficiency device could generate quantum light sources.
Area of Science:
- Nonlinear optics
- Quantum optics
- Materials science
Background:
- Optical frequency doubling is crucial for generating light at new frequencies.
- Whispering-gallery-mode resonators offer high optical confinement for nonlinear processes.
- Lithium niobate is a key material for nonlinear optical applications.
Purpose of the Study:
- To demonstrate natural phase matching for optical frequency doubling in a high-Q whispering-gallery-mode resonator.
- To achieve high conversion efficiency with low pump power.
- To explore the potential for generating quantum light sources.
Main Methods:
- Fabrication of a high-Q whispering-gallery-mode resonator from lithium niobate.
- Experimental demonstration of optical frequency doubling using continuous wave pump power.
- Theoretical analysis of three-wave mixing within the resonator.
Main Results:
- Achieved 9% conversion efficiency at 30 microwatts in-coupled continuous wave pump power.
- Observed a saturation pump power of 3.2 milliwatts, significantly lower than state-of-the-art.
- Provided theoretical insights into relative conversion efficiencies for different modes.
Conclusions:
- Natural phase matching in lithium niobate whispering-gallery-mode resonators enables efficient optical frequency doubling.
- The low saturation pump power is ideal for developing quantum noise-limited light sources.
- This work paves the way for compact, low-power nonlinear optical devices.
Related Concept Videos
01:14Sound Waves: Resonance
Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical boundary conditions (i.e., has a node at each end). A node is defined as a fixed point where the string does not move. The symmetrical boundary conditions result in some frequencies resonating and producing standing waves, while other frequencies interfere destructively. Sound waves can resonate in a hollow tube, and the frequencies of the sound...
01:03Modes of Standing Waves - I
A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. A building may vibrate for several seconds with a driving frequency matching the building's natural frequency of vibration; this produces a resonance that results in one building collapsing while the neighboring buildings do not. Often, buildings of a certain height are devastated, while other taller buildings remain intact. This phenomenon...
01:04Modes of Standing Waves: II
The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions are derived from the physical understanding of how the standing waves are sustained, that is, how the vibrating particles of the medium behave at the boundaries imposed on them.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end.
01:28Standing Waves in a Cavity
A household microwave and lasers are examples of standing electromagnetic waves in a cavity. When two conducting metal plates are placed parallel at the nodal planes, it creates a cavity where standing waves are formed. The cavity between the two planes is analogous to a stretched string held at the points x = 0 and x = L. Here, the distance 'L' between the two planes must be an integer multiple of half of the wavelength. The wavelengths that satisfy this condition are given by:
01:17Design Example: Underdamped Parallel RLC Circuit
Consider designing an oscillator circuit, a crucial component in various electronic devices and systems. The objective is to create an oscillator circuit with specific characteristics: a damped natural frequency of 4 kHz and a damping factor of 4 radians per second. To accomplish this, a parallel RLC circuit is employed, known for its ability to sustain oscillations at a resonant frequency. In this case, the damping factor is pivotal in achieving the desired performance.
Starting with a fixed...
Starting with a fixed...
01:24Characteristics of Series Resonant Circuit
Series resonance occurs in a circuit containing inductive (L), capacitive (C), and resistive (R) elements connected sequentially. At the resonance frequency, the inductive and capacitive reactances are equal in magnitude but opposite in sign, effectively canceling each other. This causes the circuit's impedance is minimal, primarily determined by the resistance R. The resonant frequency of an RLC circuit is defined as: