To verify the potential space radiation-induced degradation of a distributed feedback (DFB) laser in optical satellite communication system, the experiments of gamma and neutron radiation on DFB laser have been developed. No obvious performance degradation of the DFB laser was found within the total radiation dose 150 krad and neutron fluence 9.540 x 10(11) n/cm(2) except a slight inverse annealing. The experimental results have proved that this DFB laser is capable to be applied in a optical satellite communication system in the space.

The charge coupled device (CCD) is the key component of beacon light subsystem in optical satellite communication system. The influences of the space radiation environment on the CCD's charge transfer efficiency (CTE) and its dark current are theoretically analysed. Based on the analysis the induced CTE and dark current degradations under some typical operation temperatures and particle fluences are numerically calculated. Its further influences on the system bit error ratio (BER) are also discussed. The calculation results have proved that adding shielding layers and a temperature controlling unit are both efficient ways to improve the radiation hardness of an optical satellite communication system.

The light emitting diode(LED) is one of the key components in the optical satellite communication system,whose performance determines the reliability of the communication system.The theoretical analysis of the minority carrier′s lifetime and output power of LED device under particle radiation is made.The numerical simulation is also done based on the theoretical analysis.The calculation results prove that the increase of the doped Zn density in the active area of LED can effectively decrease the radiative lifetime of the minority carrier and it also can improves the LED′s anti-radiation performance while heightening its output power.

As the key terminal,the performance of PIN detector affects the stability and reliability of the optical satellite communication system.The properties of γ radiation and particle radiation of PIN detector under space radiation environment were researched.The results show that both radiation mechanisms impose effects on PIN detector,expressing as the increase of dark current noise and decrease of both responsivity and response bandwidth.It is indicated that the influence of space radiation on dark current noise should be the first factor to be considered in the design of optical satellite communication system.

To improve the space anti-radiation performance of the optical satellite communication system, the research of the influence on its system bit error ratio(BER) under space radiation environment was developed. The radiation-induced BER model was established, based on which the BER numerical calculations after the radiation damage of either optical source or optical detector were developed. The calculation results have proved that both γ and proton radiations can degrade the system BER by several levels, some suitable radiation shielding equipments are further needed.

The laser source is the key terminal in optical satellite communication system,whose performance affects the stability and reliability of the communication system.The theoretical research of the threshold current density for GaAs and InP laser source under space radiation environment was made.The numerical calculation results show that the change of the threshold current density is proportional to the irradiated particle flux,and the InP laser source is better than GaAs′s in the aspect of anti-space radiation.Further study was extended for vacuum environment.It shows that the influence is not obvious under this condition.The main influence is the shift of the central wavelength.

The method of precision analysis is combined with five following steps,learning the guide of precision analysis,establishing a calculation model of the target system,identifying the error and uncertainty elements in the system,calculating each element via simulation,statistics and user's manual,determining combined standard uncertainty.The analysis results demonstrate that the error of calibration optical system with blackbody source is 0.012,uncertainty is 1.07% and the number of the integrating sphere source is 0.024 and 2.51%,which mean the radiometric calibration system has good performance.The method has been used in similar tests as a guideline.

To verify the potential space radiation-induced degradation of optical satellite communication system, the γ ray radiation experiments of its key components have been developed. No obvious performance degradations of the DFB laser and photo detector module were found at the total dose less than 150krad. The EDFA seems to be the most radiation sensitive, and it comes to its malfunction through the radiation of 16.2krad. It is believed that the high energy particles’ radiation effect should be first considered when it refers to the optical terminals’ applications in the space.

The charge coupled device（CCD） is the key component of the beacon subsystem in optical satellite communication system,so its efficiency determines the performance of the communication system.The capture time constant and emission time constant affecting the charge transfer efficiency under three typical bulk traps were determined.The variations of charge transfer inefficiency with temperature,traps energy,read-out frequency,particle fluence and signal charge density were achieved,which could be the foundation for the further researches of space radiation characteristics of the optical satellite communication system.

To improve the space anti-radiation performance of the optical satellite communication system,the research on the space radiation environment′s influence on system bit error ratio(BER)is carried out.The radiation-induced BER model is established,based on which the BER numerical calculations after the radiation damage of either optical source or optical detector are developed.The calculation results have proven that both γ radiation and proton radiation can degrade the system BER by several order of magnitude.It points out that some suitable radiation shielding measures or homodyne BPSK mode are needed.

High energy particle induced single event upset(SEU) is one of the most important factors affecting the laser satellite communication system.Its physical mechanism and main research methods are given out.The OMERE 3.4 software is used to calculate the SEU ratio of satellite-borne CMOS 2164 device.The calculation results have proved that optimizations of the orbit altitude and orbit inclination could effectively decrease the SEU ratio of electronic device in satellite optical communication system.To further reduce the single event effect,besides some simple protection methods like enhancing the shield,the device selection should be considered to improve the anti-radiation performance.

The charge coupled device(CCD) is the key component of beacon light subsystem in optical satellite communication system. The influences of space radiation environment on CCD's charge transfer efficiency(CTE) and its dark current are theoretically analyzed. Based on the analysis the induced CTE degradations under some typical operation temperatures and particle fluences are numerically calculated. The calculation results have proved that adding shielding layers and temperature controlling unit are both the efficient ways to improve the radiation hardness of optical satellite communication system.

The laser source is the key terminal device in optical satellite communication system,as its performance directly determines the final bit error ration.The summary and comparison of the space radiation characteristics of common LED,LD,YAG and VCSEL equipments were developed.The results prove that the VCSEL component is of better anti-radiation performance no matter in the aspects of threshold current or output power,which is more suitable to be the laser source in optical satellite communication system.

To improve the radiation immunity of the charge coupled device(CCD) in satellite optical communication system,the ionization damage and displacement damage effects imposed on CCD in space radiation environment were analyzed.Through theoretical analysis and numerical calculation,the influences of radiation source,buried channel and bias on the charge transfer efficiency(CTE) of CCD were researched.The results show that the space radiation mainly affects the performance of CCD with the bulk dark current density and CTE.The CCD used in satellite optical communication system should be selected as the P channel CCD and set as under unbiased state when the communication system is not working.

To elucidate the total dose effect on optical fibres an experiment was developed to deliver gamma radiation to a silicon multimode fibre transmitting a 1310 nm laser beam. The radiation-induced attenuations of 5 m and 3 m long fibres under total doses of 10(4) rad and 10(5) rad were found to be 19.68 dB/km and 79.70 dB/km, respectively. There was no obvious spectral variation after radiation. The optical recovery process of the 5 m fibre was found 80 minutes after radiation, while the radiation-induced attenuation of the 3 m fibre was seen to decrease during the testing time of 100 nuns.

A potential laser jamming and damage to satellite-borne photoelectric detector by means of combined fiber lasers is proposed. Through the analysis of the photo-electromotive force of a HgCdTe photovoltaic detector it was shown that the combining of fiber lasers with an output power of 100 W was sufficiently powerful to completely laser jam a HgCdTe photoelectric detector through optical saturation. The laser-induced temperature rises under single-pulse-irradiation and continuous wave (CW) irradiation were developed. A temperature rise of 1000 K was achieved after 5 ms with CW laser irradiation. The damage thresholds under single-pulse-irradiation and continuous irradiation were calculated and showed that the combined fiber lasers produced enough power to completely laser jam a satellite-borne photoelectric detector by inflicting both "soft damage" and "hard damage".

The gamma-ray-radiation -induced damage to silicon single -mode fiber is reported. The immediate radiation-induced attenuation of the 10m fiber under total dose 104rad is 8.98dB/km, which was tolerable. Some disastrous attenuation was found a half-hour later, which rapidly increased to 642.53dB/km. No obvious spectral variation after radiation was found, except for the decreases of the spectrum power. The optical recovery phenomenon was noticed 2 days after radiation and the output spectrum power has increased from 145.5 to 185.6μW during 9 days. The experimental results have shown that the composition and its absorptivity of optical fibers play a more important role than total dose in determining the radiation-induced attenuation.

To effectively implement laser jamming,the effects on four-quadrant laser guiding detector of high power laser needs to be determined.The temperature rise distribution induced by high power laser is analyzed.The theoretical analysis and numerical calculation prove that under the irradiation of continuous high power laser the photoelectric material would be irrevocably damaged.According to the tracking system function of typical proportional guiding system,the effectiveness of laser jamming to four-quadrant laser guiding detector of high power laser is verified.

Based on the design scheme of spectral beam combining using transmitting volume Bragg grating,the experimental results for spectral beam combining of two fiber lasers are reported.The gain mediums used in this experiment were erbium-ytterbium co-doped double-cladding fibers,pumped by semiconductor lasers.The output powers of the two fiber lasers were 0.48 W and 0.71 W respectively.With grating diffraction efficiency lower than 40%,the maximal output power of 0.56 W with Absolutely combining efficiency of about 47% was achieved.The reason for the lower combining output power in the experimente was analyzed too.

To analyze the single event effects on satellite optical communication system,the single event upset(SEU) rate needs to be estimated.Through compare with differential energy spectrum method and figure of merit method,the latter is chosen to estimate the single event upset rate under different altitude and different inclination.The relation between single proton upset rate with space orbit is analyzed.The reliability index of equipment based on SEU is proposed. The numerical calculation results prove that the effect of SEU to SRAM/MOS equipment under lower orbit altitude and inclination is less,and have higher reliability.