Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
Repetition rate Independent Stabilization of Active Harmonic mode-Locked Fiber Laser
Categories for this Invention
Technology: Stabilization of Active Harmonic mode-Locked Fiber Laser
Category: Electronics & Circuits /Photonics
Industry: Electronic System & Design Manufacturing (ESDM)
Application: Mode-locked lasers, Photonic analog to digital converter, optical communications
Market: The global market size valued at USD 3.86 Billion in 2022 and is poised to grow from USD 4.31 Billion in 2023 to USD 10.36 Billion by 2031, at a CAGR of 11.6% during the forecast period (2024-2031).
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Problem Statement
- Mode locked lasers have revolutionized various technologies, producing ultrashort optical pulses with pulse repetition rates between 50 MHz and a few gigahertz (GHz).
- Active mode locking techniques can generate GHz repetition rates without shortening the optical cavity length, while harmonic mode locking aims for higher pulse repetition rates using an RF source.
- However, these lasers can be unstable in the long term due to continuous fluctuations in the cavity’s FSR due to environmental disturbances, temperature fluctuations, and vibrations.
- A control system is needed to stabilize active harmonic mode-locked lasers, maintain long-term operation, and enhance performance reliability, particularly for applications like photonic analog-digital converters, optical clock distribution, and microwave signal generation.
Technology
Process flow for stabilization of the AHML:
- Monitoring an integrated optical power in the lower-order longitudinal cavity modes
- Determining a threshold integrated power of the lower-order longitudinal cavity modes as an indicator of pulse stability
- Converting the integrated optical power of the lower-order longitudinal cavity modes into an electrical signal
- Receiving the converted electrical signal and determining an instantaneous RF power level at the RF power meter
- Digitizing the instantaneous RF power level output of the RF power meter by the ADC
- Generating a DAC correction voltage based on the instantaneous RF power level and a control logic
- Generating a DAC output voltage as a feedback correction signal based on the control logic
- Sending the DAC output voltage to a piezo electric transducer (PZT) fiber stretcher of the AHML
- Controlling a cavity length of the PZT based fiber stretcher to achieve a longitudinal mode spacing as an integral multiple of a desired pulse repetition rate
- Minimizing the integrated optical power of lower-order longitudinal cavity modes of the AHML.
Key Features / Value Proposition
Active Harmonic Mode-Lock Laser Operation
- Minimize integrated optical power of lower-order longitudinal cavity modes.
- Ensure reliable, stable operation for longer, uninterrupted duration.
- Maintain stability without performance impact from environmental disturbances.
Stabilizing Active Harmonic Mode-Locked Fiber Laser
- Functions regardless of repetition rates.
- Eliminates need for reconfiguration.
- Avoids cavity length and FSR variations.
Configuring ADC for RF Power Levels
- Receives instantaneous RF power levels.
- Determines desired RF power level.
Maintaining RF Power Level Threshold at ADC
- Maintains desired threshold for 1800s.
RF Power Level Measurement
- Measures difference between instantaneous and desired levels.
- Determines desired RF power level threshold.
- Maintains instantaneous RF power level at determined threshold.
RF Power Level Monitoring
- Controls DAC output voltage and integrated optical power.
Terminates DAC correction voltage generation
- if ADC voltage reaches PZT limit.
Photodetector operates at
- bandwidth of less than 400MHz.
Questions about this Technology?
Contact For Licensing
sm-marketing@imail.iitm.ac.in
ipoffice2@iitm.ac.in
Research Lab
Prof. Deepa Venkitesh
Prof. Balaji Srinivasan
Department of Electrical Engineering
Intellectual Property
IITM IDF Ref. 2862
Patent No: IN 545507
Technology Readiness Level
TRL- 3
Experimental Proof of concept