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Based on the temperature measurement technology of tunable diode laser ab-sorption spectroscopy, the simulation and experimental research on the temperature measurement of CO2 gas emitted by D4114B Diesel engine is realized. The light source model, gas chamber model and data detection model were established by using SIMULINK, which is more general numerical simulation tool in MATLAB. Under the simulated Diesel engine emission environment, the measured CO2 gas temperature was obtained by model simulation and analyzed. The simulation relative error was 0.077%. The marine D4114B Diesel engine was used as the test object, the visual window was reconstructed on the exhaust light path, and an optical path test system was established. The tunable diode laser was used as the detection light source to carry out on-line test research on the CO2 gas temperature in the exhaust gas emission. The relative error was 4.4%. The results show that the model built by SIMULINK can reflect the actual laser modulation effect and CO2 gas absorption. The simulation results have certain reference value for the research of tunable diode laser absorption spectroscopy temperature measurement system.

A Ho:SSO crystal was employed as an efficient saturable absorber Q switch for the pulsed Ho:YAG laser for the first time. The characteristics of the passive Q-switch Ho:YAG laser were studied with different incident pump power and different laser energy density around the Ho:SSO. The single pulsed energy varied from 8.3 μJ to 76.6 μJ with the increasing of the incident power from 2.2 W to 8.2 W. The maximum repetition rate was 42.1 kHz, and the minimum pulsed duration was 48 ns. The maximum single-pulse peak power was 1.53 kW. The output center wavelength shifted from 2090.1 nm (the continuous-wave mode) to 2091.3 nm (the passive Q-switch mode).

Represented here is an exhaust nitric oxide emission online detection method on a single-cylinder diesel engine, which is based on the tunable diode laser absorption spectroscopy. Considering the effects of different particle matter concentration in exhaust gas on detection accuracy, the direct detection approach was adopted. The wave number chosen in the present study was 1900. 07059 cm−1. The spectral parameters were calculated as a function of temperatures. And a thermo-couple was designed to detect the real-time temperature under different operating condition and modify the experimental results. All the experimental analysis demonstrated that the online detection system developed in the present study could realize the time resolution of 100 ms and effectively record the nitric oxide emission characteristics. With the high time resolution, the transient NO emission value under the transitional work condition was also obtained,which gives a new prospect to the future research on diesel engines.

An actively mode-locked Ho:SSO laser was reported for the first time, which was resonantly-pumped by a Tm-doped fiber laser. Both performance of continuous wave (CW) mode and continuous wave mode-locked (CWML) were researched in this paper. For the CW mode, the maximum output power of the 2.88 W with the central wavelength of 2112.1 nm was achieved, when the absorbed pump power was 16.2 W. The optical-optical conversion efficiency was 17.8%. Compared with the CW mode, the maximum laser output power of CWML mode was a little lower, which was 2.72 W corresponding to an optical-optical conversion efficiency of 16.8%. However, the laser output wavelength of the CWML mode was the same as the CW mode focus on 2112.1 nm. The repetition rate of CWML pulse was measured to be 81.88 MHz with the single pulse energy of 33.2 nJ and pulse duration of 282.4 ps. The peak-power was 117.6 W.