scholarly journals THz Signal Generator Using a Single DFB Laser Diode and the Unbalanced Optical Fiber Interferometer

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4862
Author(s):  
Blaž Pongrac ◽  
Denis Đonlagic ◽  
Matej Njegovec ◽  
Dušan Gleich
Keyword(s):  
Optical Fiber ◽  
Laser Diode ◽  
Optical Signal ◽  
Optical Path Difference ◽  
Sweep Rate ◽  
Path Difference ◽  
Optical Path ◽  
Signal Generator ◽  
Optical Frequency ◽  
Frequency Sweep

This paper presents a frequency-modulated optical signal generator in the THz band. The proposed method is based on a fast optical frequency sweep of a single narrowband laser diode used together with an optical fiber interferometer. The optical frequency sweep using a single laser diode is achieved by generating short current pulses with a high amplitude, which are driving the laser diode. Theoretical analysis showed that the modulation frequency could be changed by the optical path difference of the interferometer or optical frequency sweep rate of a laser diode. The efficiency of the optical signal generator with Michelson and Fabry–Perot interferometers is theoretically analyzed and experimentally evaluated for three different scenarios. Interferometers with different optical path differences and a fixed optical frequency sweep rate were used in the first scenario. Different optical frequency sweep rates and fixed optical path differences of the interferometers were used in the second scenario. This paper presents a method for optical chirp generation using a programmable current pulse waveform, which drives a laser diode to achieve nonlinear optical sweep with a fixed optical path difference of the interferometer. The experimental results showed that the proposed signals could be generated within a microwave (1–30 GHz) and THz band (0.1–0.3 THz).

Optical Path Difference Calibration Method of Optical Fiber Array Point Source Generator in Tilted-Wave-Interferometer

2018 ◽  
Vol 38 (5) ◽  
pp. 0512002
Author(s):  
李小柳 Li Xiaoliu ◽  
沈华 Shen Hua ◽  
李嘉 Li Jia ◽  
朱雪妍 Zhu Xueyan ◽  
姚德超 Yao Dechao ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Point Source ◽  
Calibration Method ◽  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Fiber Array ◽  
Optical Fiber Array

Peak-to-peak tracking method for measurement of optical path difference: Revisited

Optik ◽  
2015 ◽  
Vol 126 (24) ◽  
pp. 5420-5422
Author(s):  
H.H. Ley ◽  
A. Yahaya ◽  
Y. Munajat
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path ◽  
Tracking Method ◽  
Peak Tracking

Optical T-Bench Method for Measurement of Optical Path Difference

1963 ◽  
Vol 1 (6) ◽  
Author(s):  
Francis E. Washer ◽  
Walter R. Darling
Keyword(s):  
Optical Path Difference ◽  
Path Difference ◽  
Optical Path

Thermo-Fluid Design Simulation of Nd3+ POCl3 Transverse Flow Liquid Laser Cavity

2021 ◽  
pp. 1-31
Author(s):  
Vinod Singh ◽  
Gaurav Singhal ◽  
Prabal Talukdar
Keyword(s):  
Refractive Index ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Optical Pumping ◽  
Gain Medium ◽  
Optical Path Difference ◽  
Path Difference ◽  
Transverse Flow ◽  
Optical Path ◽  
Liquid Laser

Abstract CFD based thermal design of a transverse flow optical cavity is carried out for 1 kW Nd3+ POCl3 liquid laser source to investigate temperature and velocity distribution in the optical pumping region of the cavity. Temperature gradient and turbulence both affect the refractive index of the liquid gain medium, which results in optical path difference, divergence and hence, poorer quality of the laser beam. The main purpose of this design is to achieve uniform flow and least temperature gradient in the optical pumping region so that the optical path difference can be minimized and a good beam quality can be achieved. CFD model has been developed for carrying out thermo-fluid simulations for this thermal system and based on these simulations, an optimum geometry of inlet ports along with their position from optical pumping region have been proposed. A user defined function (UDF) is incorporated for the input of spatially varying heat source term in each cell of the optical pumping region of the cavity. Variations in refractive index and optical path difference are estimated from the temperature data using another UDF. Simulation reveals that mass flow rate between 1.5 kg/s to 2.0 kg/s maintains the optical homogeneity of gain medium. Preliminary experiments have been carried out to demonstrate the effect of flow rate on the beam divergence and thereby exhibiting the importance of present simulation work.

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