Experimental investigation ofd $\mathrm{Nd}:\mathrm{YAG}$ monolithic nonplanar ring lasers operated at $1123\mathrm{nm}$ wavelength is presented. Stable single-frequency $1123\mathrm{nm}$ laser output has been obtained with successful suppression of the strong $1064\mathrm{nm}$ radiation. Single-frequency output power of $1.25\mathrm{W}$ is demonstrated with a pump power of $3.98\mathrm{W}$ at $808\mathrm{nm}$ , which gives a slope efficiency of 39%. The laser frequency tuning range is over $3\mathrm{GHz}$ , and the average tuning rate with temperature is $-2.6\mathrm{GHz}∕°\mathrm{C}$ . A strong iodine absorption line can be covered within the laser frequency tuning range.