## 1 Introduction  
Conventional laser is usually formed by three basic elements: a gain medium, an exciting source, and an optical resonant cavity. However, since [PERSON] [1] theoretically proposed in 1968 that the optical feedback of stimulated emission can be provided by scatterers, a new avenue for the realization of lasers without cavity has been opened. Random lasers, whose optical feedback is the multiple scattering caused by random fluctuations of the dielectric constant in space, have attracted widespread attentions due to their unique physical mechanisms and potential applications [2; 3; 4; 5; 6]. Generally, the generation of random lasers must satisfy two conditions: (i) light is amplified by the stimulated emission and the feedback comes from the multiple scattering, and (ii) there is an energy threshold which is defined by the sharp narrowing of the spectrum and the sharp increase of the peak intensity as the pump energy increases. When the pump energy exceeds the threshold, the total gain overcomes the total loss in the random system, which results in the occurrence of random lasers. In the past few decades, a wide range of materials, such as semiconductor [7], \(\pi\)-conjugated [8], human tissues [9], quantum dots [10], metallic nanoparticles [11; 12], polymers [13], and liquid crystals (LCs) [14; 15; 16] have been used to realize random lasers. Metal nanoparticles, such as gold (Au) nanoparticles and silver (Ag) nanoparticles are often used to enhance the performances of random lasers [11; 12; 17; 18; 19; 20]. For example, [PERSON] et al. [17] reported in 2005 that the random lasers formed by suspending Ag nanoparticles in the laser dye solution. In 2006, [PERSON] et al. [18] studied the dye-doped polymer film random lasers enhanced by Au nanoparticles. In 2016, [PERSON] et al. [19] investigated the influence of Ag nanoparticles on random lasers from dye-doped nematic liquid crystals. In 2019, the recyclable random lasers assisted by metal nanoparticles in DCM dye doped polyvinyl alcohol (DCM-PVA) thin films are studied [20]. Nematic liquid crystals are one of ideal materials for fabricating random lasers because of its unique optical characteristics. The scattering intensity of nematic liquid crystals is very strong in the visible region, which is about \(10^{6}\) times larger than that of the isotropic liquid [21]. Moreover, the director of nematic liquid crystals is easily modulated by the external stimuli including the electric field, magnetic field, temperature, and light [22; 23; 24; 25]. Recently, we reported a plasmonic random laser of dye-doped nematic liquid crystals with TiN nanoparticles in capillary tubes. Advantages of this random laser enhanced by localized surface plasmon resonance (LSPR) of TiN nanoparticles have been discussed in our article [26]. However, the manipulation of the random laser emission from dye-doped nematic liquid crystals with TiN nanoparticles (NPDDNLC) in non-oriented cells has not been studied. Over the past few decades, plenty of methods have been proposed for controlling the performance of random lasers [27; 28; 29; 30; 31; 32; 33]. Some deals with adjusting the scatterers, others depend on controlling the gain. However, these methods either change the random structures or use different samples. This needs a complex manufacturing process, which limits the actual application of random lasers. For most applications, active manipulation of random lasers is more desired. Among these methods, the partial pump control, which can be operated in a single random sample, are simpler. Therefore, we adopt this method to control the performance of random lasers from dye-doped nematic liquid crystals with TiN nanoparticles in non-oriented cells. In this work, we achieve experimentally the control of the high-quality and low-threshold random lasers by tuning the shape of the pump spot.