Atomic Oscillator Optical Module With Etalon Sideband Filtering
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Solution Overview
Problem
Atomic oscillators using CPT with semiconductor lasers face reduced frequency stability due to the irradiation of fundamental waves, which cause the AC Stark effect, as they emit both sideband and fundamental waves, with the latter not contributing to the EIT phenomenon.
Innovation Solution
An optical module with a wavelength selection section, including an etalon and temperature control, is used to selectively transmit sideband waves, reducing or eliminating fundamental waves from reaching the alkali metal atoms, thereby suppressing frequency changes and enhancing stability. This module includes a light source emitting both fundamental and sideband waves, a gas cell for alkali metal gas, and a light detection section to monitor intensity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor laser is used as a light source to emit both fundamental wave and sideband waves, then the EIT phenomenon can be achieved, but the fundamental wave causes AC Stark effect and reduces frequency stability
Solution Approach 1:
The patent extracts and removes the harmful fundamental wave from the light emitted by the semiconductor laser, allowing only the sideband waves to reach the alkali metal atoms. This is achieved through wavelength selection that separates the fundamental wave (center wavelength) from the sideband waves, eliminating the source of AC Stark effect while preserving the EIT phenomenon.
Solution Approach 2:
The patent introduces a wavelength selection mechanism as an intermediary between the semiconductor laser and the alkali metal atoms. This intermediary selectively transmits the sideband waves while blocking the fundamental wave, thus mediating the interaction to achieve EIT without AC Stark effect.
2Reliability
If the drive current of the semiconductor laser is modulated to generate sideband waves, then the EIT phenomenon can be achieved, but the fundamental wave is also emitted and reduces oscillator stability
Solution Approach 1:
The patent extracts the harmful fundamental wave component from the modulated laser output, allowing only the useful sideband waves to proceed to the gas cell. This extraction is performed through wavelength-selective filtering that distinguishes between the center wavelength (fundamental) and the modulated sideband frequencies.
Solution Approach 2:
The patent converts the harmful fundamental wave emission into a beneficial situation by using wavelength selection to suppress it. The modulation that originally produced both fundamental and sideband waves is transformed into a useful mechanism, where the fundamental wave is eliminated and only the sideband waves contribute to the EIT phenomenon, thereby improving oscillator stability.
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
The solution effectively suppresses frequency variations caused by the AC Stark effect, leading to an atomic oscillator with improved frequency stability and reduced power consumption by using a surface-emitting laser and a simple temperature control mechanism.
Implementation Method 1
a wavelength selection section receiving the light from the light source, and adapted to transmit the sideband waves out of the light input
Implementation Method 2
a temperature control section adapted to control temperature of the etalon
Implementation Method 3
a light detection section adapted to detect an intensity of light transmitted through the gas cell
Implementation Method 4
a semiconductor laser is used as a light source. In the atomic oscillator using the semiconductor laser as the light source, for example, the drive current of the semiconductor laser is modulated so that a sideband wave is generated
Implementation Method 5
the drive current of the semiconductor laser is modulated so that a sideband wave is generated in the light emitted from the semiconductor laser
Implementation Method 6
when two resonant lights having wavelengths (frequencies) different from each other are simultaneously irradiated to an alkali metal atom, the absorption of the two resonant lights is stopped
Implementation Method 7
When the fundamental wave is irradiated to the alkali metal atom, there is a case where the wavelength (frequency) of light absorbed by the alkali metal atom is changed (AC Stark effect)
Data Source
AI summary
An optical module for an atomic oscillator uses a quantum interference effect. The optical module includes a light source adapted to emit light including a fundamental wave having a center wavelength, and sideband waves of the fundamental wave, a wavelength selection section receiving the light from the light source, and adapted to transmit the sideband waves out of the light input, a gas cell encapsulating an alkali metal gas, and irradiated with light transmitted through the wavelength selection section, and a light detection section adapted to detect an intensity of light transmitted through the gas cell. The wavelength selection section includes an etalon and a temperature control section adapted to control temperature of the etalon.