Optical Cavity Transfer Lock for Wide-Range NIR-VIS Laser Stabilization
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Solution Overview
Problem
Existing systems for stabilizing laser light in the near infrared - visible (NIR-VIS) range lack reliability and speed, and require complex setups involving frequency combs or atomic resonances that are costly and lack long-term stability.
Innovation Solution
A system using cavity transfer lock to a frequency shifted C-band stable laser, employing a master laser and a slave laser, with PDH servos and electronic controls to stabilize the slave laser over a wide frequency range without altering the intrinsic stability of the frequency reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency combs or atomic resonances are used to stabilize laser light, then frequency stability can be achieved, but the system becomes costly and lacks long-term stability
Solution Approach 1:
The patent uses an optical cavity as an intermediary device to transfer frequency stability from a C-band master laser to a slave laser in the NIR-VIS range. The cavity acts as a mediator that enables frequency transfer without requiring direct atomic resonance or frequency comb mechanisms, thereby reducing system complexity while maintaining long-term stability through the cavity's high Q-factor
Solution Approach 2:
The patent creates a frequency copy by transferring the stability characteristics of the C-band master laser to the slave laser through the optical cavity. The cavity transfer lock technique effectively copies the frequency reference properties from one laser to another across different wavelength ranges, eliminating the need for complex atomic resonance systems
2Speed
If existing stabilization systems are used, then frequency control can be achieved, but the stabilization speed and reliability are insufficient
Solution Approach 1:
The patent implements feedback control through PDH (Pound-Drever-Hall) servos that continuously monitor the laser frequency relative to the optical cavity resonance and apply real-time corrections. This feedback mechanism enables both fast stabilization response and high reliability by maintaining the laser frequency locked to the cavity reference
Solution Approach 2:
The system performs preliminary frequency shifting of the master laser to match the desired slave laser frequency before the actual frequency transfer process. This preliminary action prepares the frequency reference in advance, enabling faster and more reliable stabilization when the slave laser is locked to the cavity
3Adaptability or versatility
If a wide frequency tuning range is implemented, then versatility is improved, but maintaining high stability becomes difficult
Solution Approach 1:
The patent employs dynamic frequency shifting of the master laser using acousto-optic modulators (AOMs) to adapt the reference frequency to different desired output frequencies. This dynamic adjustment capability allows the system to maintain high stability across a wide tuning range by continuously updating the frequency reference through the optical cavity transfer lock mechanism
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
Enables precise frequency tuning of the slave laser over multiple GHz with digital control, maintaining high stability and reducing noise, suitable for applications in optical communications and telecommunications.
Implementation Method 1
an optical cavity, which optical cavity is configured for directing the first portion of the master light beam reflected therefrom back
Implementation Method 2
a voltage-controlled oscillator, VCO, of phase-locked loop, PLL, which is dithered by PDH reference oscillator at frequency from 1 MHz to 100 MHz which imposes phase modulation for PDH scheme
Implementation Method 3
a photodiode, which photodiode is configured for providing an electrical signal to a first PDH servo
Data Source
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AI summary
The subject matter of the present invention is a system for stabilising NIR-VIS laser to any frequency using cavity transfer lock to frequency shifted C-band stable laser, comprising: a master laser (10), configured for emitting a master light beam towards a sampling plate (54a), the sampling plate (54a) configured for splitting the master light beam into two light beam portions and for directing a first portion (51a) of said master light beam through a sampling plate and a polarising beam splitter, PBS, (15) and a quarter-wave plate, QWP, (16) to an optical cavity (100), which optical cavity (100) is configured for directing the first portion of the master light beam reflected therefrom back through the quarter wave plate (16) and the polarising beam splitter (15) towards a photodiode (18), which photodiode (18) is configured for providing an electrical signal to a first PDH servo (6a) for cavity (100) stabilisation to the master laser (10), wherein the first PDH servo (6a) is electrically connected with the cavity (100) and the cavity (100) is configured for receiving a slave light beam (52a) from a slave laser (60), through a polarising beam splitter, PBS, (65) and a quarter-wave plate, QWP, (66) and for directing the slave light beam reflected therefrom (52b) back through the quarter wave plate (66) and the polarising beam splitter (65) towards a photodiode (68), which photodiode (68) is configured for providing an electrical signal to a second PDH servo (6b) for slave laser (60) stabilisation to the cavity (100), and for directing a second portion (19) of said master light beam via light pathway to frequency shift and dither subsystem, comprising a reference light beam modulator (21) and then through an atomic reference (3) to a reference photodiode (detector) (20) with demodulator (4), which is configured for providing a reference intensity electric signal (31) to the master laser (10). Furthermore, the invention includes also a method of stabilising NIR-VIS laser to any frequency using cavity transfer lock to frequency shifted C-band stable laser, performed in such a system.